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J29i
Jarvis
Investigation on jigging
INVESTIGATION ON JIGGING.
BY
ROYAL PRESTON JARVIS, E.M., A.M.,
3 rofessor of Mining and Metallurgy in the University of Tennessee,
KNOXVILLE, TENN.
STRMITTED IN PART FULFILLMENT OP THE REQUIREMENTS FOR THE
DEGREE OF DOCTOR OF PHILOSOPHY, IN THE FACULTY
or PURE SCIENCE, COLUMBIA UNIVERSITY,
MARCH, 1908.
NEW YORK, N\ Y.
1908.
BIOGRAPHICAL SKETCH.
ROYAL PRESTON JARVIS was born in Riverton, Iowa, Feb. ~J8,
875. In the spring of 1880 he moved with his parents to the
otate of Colorado, and continued to reside in that State until
1 900, with the exception of a few brief visits East;. His early
education was obtained in the schools of Crested Butte, Colo.,
graduating from the Gunnison High School in 18f93. In the.
fall of this year he matriculated at the Colorado School of
Mines, graduating therefrom with his class in 18157. Later 'he
accepted the position of assayer in the works of the Bimetalli'
Smelting Co., of Leadville, Colo., and remained m the employ
of this company until the plant was permanently clu ed in 19'"
In the fall of 1900 he entered Columbia Universit
student, and attended most of the session of 1900-
fall of 1901 he was appointed chemist to the Cia.
a grarlu
31. In the
tfetalurgica
de Torreon, Torreon, Mexico. He remained with tlais company
until the spring of 1903, finally filling the positioi/of Assistant
Superintendent of the plant. Mr. Jarvis was appointed to the-
chair of Mining and Metallurgy in the Washington State Col-
lege in the fall of 1903, which position he occupied for three
years. In the fall of 1906 he resumed his work) in Columbia
University, and received the degree of A.M. in 1907. He
was appointed in the spring of 1907 to fill the 'iewly-created
chair of Mining and Metallurgy in the University of Tenne
at Knoxville.
SUBJECT TO REVISION.
: 7 /V
[TRANSACTIONS OF THE AMERICAN INSTITUTE OF MINING ENGINEERS.]
Investigation on Jigging.*
BY ROYAL PRESTON JARVIS, E.M., A.M.,f KNOXVILLE, TENN.
(Chattanooga Meeting, October, 1908.)
TABLE OF CONTENTS.
PAGE
I. INTRODUCTION, 1
II. REVIEW OF PREVIOUS INVESTIGATIONS, 2
III. RESUME OF RESULTS OF PREVIOUS PRELIMINARY WORK, . . 4
1. Hydraulic-Classification Tests, 5
2. Pulsion-Jig Tests, 5
3. Vezin Laboratory-Jig Tests, 7
A. Suction, 8
B. Feed-Water and Rate of Feed, 9
C. Filter-Bed, 9
D. Length and Number of Strokes, 9
E. Concentration, 9
F. Specific Gravity, 9
4. Five-Sieve Harz-Jig Tests, 9
IV. TESTS WITH THE JARVIS LABORATORY-JIGS 11
1. Construction, ........... 12
2. Materials and Other Accessories, 17
A. Screens, 17
B. Sieve-Sizes, 18
C. Bedding, 18
D. Minerals, 18
E. Specific Gravities, 18
F. Feed, 19
3. Method of Conducting the Tests, 20
4. Record of Results, 22
5. Discussion of Results, . 45
V. DISCUSSION OF PULSION AND SUCTION, 59
VI. DISCUSSION OF ACCELERATION, 62
VII. RESUME AND CONCLUSIONS, 63
I. INTRODUCTION.
The jig, in one form or another, continues to hold a leading
place among the machines designed to separate two or more
* Submitted in part fulfillment of the requirements for the degree of Doctor of
Philosophy to the Faculty of Pure Science, Columbia University, and accepted
for publication in the Transactions of the American Institute of Mining Engineers.
f Professor of Mining and Metallurgy at the University of Tennessee, Knox-
ville, Tenn.
2 INVESTIGATION ON JIGGING.
minerals of different specific gravities. It is simple in construc-
tion, easily operated, capable of treating large quantities in a
short time, and highly efficient under various conditions.
The question, whether the material to be jigged has first been
sized, determines the two principal methods of jigging. Jigging
preceded by close sizing, generally known as the Continental or
German system, involves a more or less elaborate series of
screens or trommels, with attendant cost for installation, opera-
tion, and repairs. Jigging without sizing, known as the English
system, is, according to Munroe, 1 " a development of the hand-
jigging formerly employed in Cornwall . . . and introduced
by English miners to this country." In its simplest form,
the method consists in jigging an ore-mixture previously crushed
to some maximum size (although, in some cases, even this pre-
liminary is omitted) on a relatively coarse sieve, and then jig-
ging again on a finer sieve, the material passing through the
first sieve and bedding. While many modifications have been
necessary to adapt it for use in mills of large capacity, where
hand-work was necessarily replaced by machines, the principle
remains the same; the fact that the English system has been
successfully employed, both in this country and abroad, is well
known; and arguments have been made for its efficiency and
applicability in a wider sphere than it has occupied hitherto.
II. REVIEW OF PREVIOUS INVESTIGATIONS.
The fact that treating a mixture of minerals under jigging
conditions increased the amount of mineral saved; or, as Pro-
fessor Richards aptly terms it, " the extra jig-catch," has long
been known. To account for this fact a number of theories
have been proposed. The work of Rittinger 2 in this field has,
for many years, been a classic in the literature of ore-dressing.
For the purposes of my present paper, however, the work of
two American investigators, Prof. H. S. Munroe and Prof. R. H.
Richards, is chiefly concerned.
Professor Munroe has given the results of an elaborate series
of experiments, 3 and his deductions, based largely on theoretical
grounds, of this work. After reviewing briefly the two systems
of jigging, followed by a discussion of Rittinger's formulas and
1 Trans., xvii., 637 (1888-9). 3 Aufbereitungskunde, pp. 165, 270.
3 Trans., xvii., 657 (1888-9).
INVESTIGATION ON JIGGING.
the derivation of them, and after a careful study of the behavior
of grains (usually shot) in a tube en masse, acted upon by a rising
current of water, he is led to conclude that the interstitial cur-
rents play a very important role, and are responsible for the
high ratios of concentration obtainable in the English system
of jigging. Since his conclusions bear directly upon the present
investigation, they are given in full, as follows :
' ' 1. Bodies falling through water in a tube do not attain as high a velocity as in
falling through the same medium in large vessels.
" 2. The falling velocity is but little affected when the diameter of the body is
less than one-tenth that of the tube.
"3. The falling velocity is the more retarded as the diameter of the body
approximates that of the tube.
"4. A sphere four-tenths the size of the tube will develop the greatest falling
velocity, and will require a current of maximum velocity to support or raise it.
"5. Grains falling en masse are really moving in confined channels, and follow
the law of the movement of bodies in tubes. The falling velocity, and the velocity
of the current necessary to support or raise a mass of grains, increase and dim-
inish with the distance apart of the grains.
"6. The diameter of the channel in which the single grain moves equals the
cube root of the volume of the grain with its proportion of the interstitial
space. . .
"7. In a mass of grains of different sizes, the large grains move relatively in
smaller channels than the small grains. The ratio of the diameters of equal-fall-
ing grains of quartz and galena, under such conditions, is 31 to 1, instead of 4 to
1 , which latter ratio holds good for free-falling grains only.
"8. The formulae for grains moving in tubes, when applied as above to grains
moving en masse, enable us to compute the velocity of jig-currents and thus deter-
mine the proper length and number of strokes of the jig-piston. The old formulae
gave results many times too large.
"9. The present investigation demonstrates that close sizing is not necessary for the
separation of different minerals by jigging, unless the difference in specific gravity is
small. . . .
" 10. Downward currents are apparently necessary to success in jigging through
a bed. This requires confirmation by experiments on a larger scale.
"11. Very fine material, less than y 1 ^ millimeter in diameter, can be treated suc-
cessfully on jigs, if treated with coarse stuff, the concentration taking place in the
small interstitial channels between the grains forming the mineral bed. For the
treatment of fine stuff on jigs, dose sizing is a positive disadvantage. Jigs work well on
mixed stuff, and very badly on fine stuff alone. Stuff less than four-tenths the
size of the smallest interstitial channels cannot be treated successfully in this way.
"12 The size of the mesh of the jig-sieve has a very important influence, and
must be proportioned to the work to be done.
"13. The English method of jigging without sizing, except possibly so far as
is necessary to remove the very finest slimes, has many advantages, and should be
more generally adopted."
Professor Richards, 4 in a very careful and elaborate investiga-
Trans., xxiv., p. 409 (1894).
4 INVESTIGATION ON JIGGING.
tion on the question of jigging relatively small sizes, treats it
under four heads: (1) the law of equal-settling particles; (2)
the law of interstitial currents ; (3) the law of acceleration ;
and (4) the law of suction. These four laws are supposed to
govern all jigging operations. Practically, Professor Richards's
full conclusions are : 5
"The two chief reactions of jigging are pulsion and suction.
"The effect of pulsion depends upon the laws of equal-settling particles, inter-
stitial currents, and, possibly, also of acceleration. The chief function of pulsion
is to save the larger grains of the heavier mineral, or the grains which settle
faster and farther than the waste.
' ' The effect of suction depends upon the interstitial factor of the minerals to be
separated. ... If this factor is greater than 3.70, suction will be efficient and
rapid. If the factor is less than 3.70, suction will be much hampered and
hindered. The use of a long stroke will help to overcome this difficulty. The
chief function of suction is to save the particles that are too small to be saved by
the laws of equal-settling particles, and of interstitial currents, acting through the
pulsion of the jig.
" For jigging mixed sizes, pulsion with full suction should be used.
' ' For jigging closely-sized products, pulsion with a minimum of suction should
be used."
He concludes by saying, in effect :
In jigging minerals having an interstitial factor greater than 3.7, sizing is sim-
ply a matter of convenience, although the fine sizes should be removed in some
suitable manner. But if the factor is less than 3.7, then the jigging of mixed sizes
cannot give a perfect separation, and if this is desired, then close sizing must be
adopted, and the closer the sizing the more perfect the jigging. As an expedient,
however, there are often cases where a satisfactory separation may be attained
without sizing.
The differences in the conclusions of the two investigators
above quoted have been chiefly influential in suggesting this
present investigation, which was begun in the fall of 1906, and
the results of the work done in the Mining Laboratory of the
Columbia School of Mines have been embodied in a paper
submitted to the Faculty of Pure Science in Columbia Univer-
sity. Since most of the work done then was preliminary to
that recently undertaken, I include herewith a resum& of my
former results and conclusions.
III. RESUME OF THE RESULTS OF PREVIOUS PRELIMINARY
WORK.
In the following investigation an effort was made to deter-
mine, among other things: (1) the conditions and laws of
5 Trans., xxiv., 485 (1894).
INVESTIGATION ON JIGGING. 5
hydraulic classification ; (2) the conditions and limitations of
iigging in the pulsion-jig; (3) the effect of varying the length
and number of strokes per minute in the Vezin laboratory-jigs;
(4) experiments with a large 5-compartment Harz jig to deter-
mine the limits and perfection of separation effected in an ore
containing galena and sphalerite with a quartzose gangue.
Considered briefly, the results of these tests, in the above-
named order, are :
1. Hydraulic Classification.
A number of tests were made with quartz paired with
galena, antimony, arsenopyrite, magnetite, sphalerite, etc., in
different proportions, and with a velocity varied between wide
limits, in order to determine whether a fixed ratio existed as to
the diameters of the grains of the two minerals. All tests under
this head were made in a Munroe hydraulic laboratory-classi-
fier. Without going into details of the methods, etc., the re-
sults indicated that whether or not a more perfect separation
was effected in the classifier-tube itself, the manner of drawing
off the classified products always resulted in giving a large
proportion of mixed products, and after a number of calcula-
tions upon different drawings, similar to the manner detailed
under the pulsion-jig tests, and described by Professor Rich-
ards, 6 proved to my satisfaction that no such ratio existed with
classified products under the conditions the above type of clas-
sifier was operated and the products removed.
2. Pulsion-Jig Tests.
The largest size of Munroe hydraulic classifier was first
fitted up in such way that a column of ore 5 to 6 in. long was
supported upon a bedding of large grains, and then treated
with a pulsating current of water. The tube in which the
jigging took place had a diameter of about 1.75 in., and the
pulsion was effected by compressing a rubber tube connecting
the bottom of the ore-column with a pressure-head of water.
The compression of the tube was effected both by mechanical
means and by hand, and apparently it made little difference
which method was used. The bedding-grains served only to
support the ore-column and confine it within the tube ; and in
6 Op. tit., p. 450, et seq.
6 INVESTIGATION ON JIGGING.
drawing off the products this was always first to be removed.
The results of jigging under these conditions and the removal
of the jigged product namely, by allowing the jigged material
to subside gradually into a rubber tube connected with the re-
ceptacle which supported the bedding, if it may be called such,
and which was really the hutch of the jig, were that after dry-
ing, screening, weighing, and analyzing the different screen-
products from a number of drawings, and finally calculating
the ratios between the diameter of the grain of quartz and
that of the other mineral paired with it, no such ratio as that
given by Richards could be obtained under such conditions,
but the tests were in all respects duplicates of the first series
run with the classifier operated under the conditions of hydraulic
classification.
It was found, however, that if the jigged products were not
removed from the jigging-tube as above described, but, instead,
a screen attached to the lower end of the jigging-tube, and the
mixture of minerals jigged on this screen, and then instead of
drawing off the products through the rubber tube at the bot-
tom the entire apparatus was dismantled, and the jigged prod-
ucts removed from the tube by inserting a piston and forcing
the ore-column from the bottom of the tube, cutting sections
at equal intervals, that approximate concordant results were
obtained. These sections, which were cut off at equal intervals,
and usually eight or nine in number, were dried, sized on a nest
of sieves, weighed, and analyzed. Ratios of diameters were
then calculated for some four or five drawings, in which the
mixed grains occurred, according to the method described by
Richards, 7 which was as follows : The average diameter of the
quartz-grains was obtained by multiplying all the quartz-weights
in a particular drawing by their diameters, and dividing the sum
of the products by the sum of their weights ; and similarly for
the other mineral paired with it. The average diameter of the
quartz-grain thus determined is divided by the average diame-
ter of the grains of the other mineral, and the quotient is
the desired ratio. Table I. gives the ratios that were obtained
with the pulsion-jig, the material in nearly all cases being sized
between 0.15 and 2 mm. For purposes of comparison I have
included the ratios obtained by Professor Richards 8 with a
7 Trans., xxiv., 450 (1894. Trans., xviv., 463 (1894).
INVESTIGATION ON JIGGING.
pointed tube, the results of which he considers to hold true for
the pulsion-jig as well.
TABLE I. Equal-Settling Ratios of Minerals in Pulsion-Jigs.
Name and Specific Gravity.
Ratio for
Pulsion-Jig.
Richards's Ratio.
Quartz,
f Galena, 7.14
i Antimony, 6.66
Arsenopyrite, 5.71
Magnetite, 4.76
Sphalerite 3 70
5.80
5.20
4.42
3.65
2.61
5.842
4.896
3.737
not given.
2.127
In the tests of Table L, 50 per cent, by volume of each min-
eral was used. It seems evident, therefore, that under the con-
ditions that exist under the influence of pulsion alone, the free-
settling ratios obtained with Rittinger's formula 9 are increased,
but by no great amount.
3. Vezin Laboratory-Jig Tests.
Without going into the details of construction of this very
useful little laboratory-apparatus, suffice it to say that the piston
is driven by a variable-speed shaft, with a disk and friction-
wheel, and the number of strokes may be varied from 100 to
300 per min., and, with a double eccentric, the length of stroke
from to 1.25 in. (31.7 mm.). The box carrying the sieve is
attached to the body of the jig by means of clamps, so that,
together with the ore and bedding resting on the sieve, it may
easily be removed and the contents examined, or another box
with its attached sieve substituted. In all tests with the Vezin
jig a sieve of 8-mesh (2.2 mm. square hole) was used. The
bedding was in most cases sized between the limits of 2.5 and
3.3 mm., and maintained at a thickness of 0.75 in. (19 mm.).
The jig was driven from a counter-shaft by an electric motor,
so that a uniform speed was secured. The feed in all cases was
sized between the limits of 0.10 and 1.9 mm., and the various
mixtures were made up by volume to contain 3 of quartz and
1 of the heavier mineral. From 1.6 to 2.0 kg. represented the
amount generally employed in each test. After this quantity
had been run over the jig it was stopped, the sieve-box removed,
the contents placed in a large pan and dried, the hutch-work
9 Trans., xvii., 639 (1888-9; ibid., zxiv., 411 (1894).
8 INVESTIGATION ON JIGGING.
drawn off, the water decanted and treated in the same way, and
finally the tailings were freed as far as possible from water and
dried. The three products were then sized separately on a nest
of sieves, each size weighed and analyzed, the material being
subsequently used again for another test.
It is evident that in so simple a machine as the Vezin jig
there are a number of factors that may be made either constant
or variable. Thus the length of stroke and number per min.
are easily varied, or may be kept constant; the size of the
grains constituting the bed, and its thickness, may be varied
within limits, although this is likely to vary with other factors,
especially the piston-speed ; then the quantities of water used
on the piston side, with the feed and the amount discharged
from the hutch, as well as the rate of feed, may also be varied.
In these tests the length and number of strokes were the prin-
cipal variables, and also the amount of suction, of which there
are a number of degrees, limited as follows :
(A) Full suction. In which the hutch-spigot is fully open,
and the water thus discharged is supplied entirely by increasing
the amount added with the feed, and, if possible, cutting down
the amount supplied to the piston side.
(B) Part suction. In which the hutch-spigot is not fully open,
and does not discharge a quantity equal to the extra amount
added with the feed.
(C) Balanced suction. In balanced suction the hutch-spigot
is closed and the feed-water and piston-water are equal ; or the
hutch-spigot is partly or fully open, and the amount thus dis-
charged is supplied entirely from the piston side.
The results obtained indicate the following conclusions :
A. Suction. With full suction, (A), the bed was not mobile,
and after a few minutes' feeding the jig was very badly choked
and little or nothing passed into the hutch. After trying a few
tests with the same bad results, full suction was considered
impracticable. In the case of part suction, (B), the mobility
of the bed was decreased in proportion to the amount of suc-
tion, and with it a decrease in the amount of coarse mineral
passing into the hutch, but with a corresponding increase in
the amount of fine material without a noticeable enrichment.
The best results were obtained with balanced suction, having
the spigot completely closed, although the results with the
INVESTIGATION ON JIGGING. 9
spigot partly or fully open did not differ materially from those
of full suction (A).
B. Feed- Water and Rate of Feed. These factors were kept as
nearly constant as possible, and the effect of varying them was
not considered.
C. Filter-Bed. The thickness and the size of the filter-bed,
also, were made a constant. It was found, however, that the
shape of the grains of the bedding does influence the ease and
rapidity with which the mineral passes into the hutch. Thus
with antimony and arsenopyrite, both of which break into long,
pencil-shaped grains, the sieve became quickly blinded, which
interfered with the free passage of grains below, and required
a long, heavy stroke to dislodge them.
D. Length and Number of Strokes. The results of the tests
seemed to show that the character of the separation is not
directly dependent upon absolute piston-speed, but that the
quick, short stroke was more efficient, and resulted in a cleaner
hutch-product, and relatively more of it, than a longer stroke
of less frequency, but of the same piston-speed.
E. Concentration. If the diameters of the grains of the heavy
mineral jigged, and of the bedding-grains (and therefore the
diameter of the sieve-hole), do not differ by any large amount, a
clean separation can easily be made. With an increase in
these ratios, perfect separation is impossible. Stated in other
words, with bedding of a definite size, and hence a fixed sieve-
aperture, the finer the grain the more difficult is its separation
on the jig.
F. Specific Gravity. Within rather wide limits, the difference
in the specific gravity of the heavier mineral paired with quartz
did not influence greatly the ease with which it could be sepa-
rated, or a good concentration attained.
4. Experiments with a 6-Sieve Harz Jig.
Two runs were made as nearly as possible under practical
conditions to determine to what extent the conclusions derived
from the Vezin-jig tests were applicable to an ordinary jig. The
ore used for the work contained 6 per cent, of mineral about
half sphalerite and the balance galena, with a quartzose gangue.
The jig was bedded with material sized between 5.2 and 6.6 mm.
The first compartment was bedded with a clean galena, the
10 INVESTIGATION ON JIGGING.
second with sphalerite, and the third, fourth, and fifth with
mixtures of sphalerite and quartz. The thickness of the bed-
ding averaged from 20 to 30 mm. at the beginning of the run.
All beds naturally tended to increase in thickness, since no
products were skimmed off during the run.
The jig differed in no respect from the common type of Harz
jig. Each sieve-compartment was 16 by 20 in. (406 by 512 mm.)
in section, with pistons of equal area. The lengths of strokes
could be adjusted between limits of to 50 mm., and within
a considerable range in the number per min. in the experi-
ments, from 175 to 180. The actual piston-speeds used ranged
about as follows : first compartment, 75 mm. ; second, 66 to
70 mm. ; third, 57 to 67 mm. ; fourth, 45 to 58 mm. ; and fifth,
45 to 50 mm. per sec. Only the hutch-products and tailings
were examined.
The ore, sized between and 4.8 mm., round hole, was
delivered to the jig through a centrifugal pump. All prod-
ucts traveled in closed circuits, and were finally returned to
the centrifugal elevator or pump to be passed again over the
jig. The spigots constantly discharged their products, and from
these discharges time-samples were cut out. The run occu-
pied exactly an hour, so that after weighing each of the prod-
ucts in this case six with the tailings, data were at hand for
calculating the capacities ; and after screening, weighing, and
analyzing, a complete record of the run was made. The results
of these tests showed that the differences in length of stroke,
or number of strokes per rain., were not sufficient to produce a
marked difference in the character of the concentrate; that
most of the galena was saved in the first hutch and most of the
sphalerite in the second; that the third, fourth, and fifth
hutches carried very little galena, but more sphalerite. It was.
found that the first hutch-product contained 57 per cent, of
galena, and of this nearly 70 per cent, was larger than 1 mm.
in diameter; and that sizes finer than this contained more
quartz and less galena. The results seemed to indicate the
necessity of first removing stuff less than 0.4 mm. in diameter
in order to increase the richness of the product. The first
hutch-product contained no coarse sphalerite, and only when
the material was as small as 0.2 mm. was any considerable
amount present. This seems to indicate that an almost perfect
INVESTIGATION ON JIGGING. 11
separation of these two minerals (galena and sphalerite) from
each other and quartz, under the conditions with which the
jig was operated, was possible if the feed had been sized
between the limits of 0.4 and 4.8 mm. The second hutch,
which carried most of the sphalerite, shows that the coarse
sizes pass through the sieve of the jig less readily than galena.
Not until the material was reduced to 1.5 mm. was any marked
percentage noticeable in the product. From 0.4 to 1.5 mm.
most of the saving was made. Evidently, the cause for so
little very fine stuff in the second hutch-product was owing to
the fact that most of it was caught in the first. Under the con-
ditions obtaining in the second compartment, a very satisfac-
tory separation could be made on all sizes below 1.5 mm.
The results from the third compartment were like those of
the second. The fourth and fifth hutches indicated a further
saving of sphalerite, but between somewhat different size-limits
than in the second and third ; the limits in the last two com-
partments varied between 0.7 and 2.5 mm., with very little fine
stuff'. This result indicates that in the first compartments more
fine material is present, making a denser and more impervious
bed, and that the large grains cannot so easily pass through it ;
and that in the last compartment the bed is more open and
porous, and hence larger grains can more readily pass into the
hutch. An examination of the tailings indicated that the loss
in the fine material was very small, but by far the largest loss
was in the four coarsest sizes, which were mixed grains or
middlings, and to reduce this loss further crushing must be
done. The results indicate that in order to separate sphalerite
and quartz, a jig of at least three compartments should be
used ; since smaller differences in the specific gravity of these
minerals require a longer time to effect the separation. In the
case of a heavy mineral, such as galena, one or two compart-
ments will effect a perfect separation.
IV. EXPERIMENTS WITH THE JARVIS LABORATORY-JIG.
In order to investigate particularly the effect of pulsion and
suction upon jigging, and upon accelerated and retarded strokes,
I designed a special jig, with which I conducted a series of experi-
ments and obtained the following results :
12 INVESTIGATION ON JIGGING.
1. Construction.
Figs. 1, 2, and 3 are detailed drawings of the Jarvis laboratory-
iig, with the exception of the variable-speed shaft, which is of
the ordinary disk-and-friction-wheel pattern. Figs. 4 and 5 show
the designs of the cams used. The screen-area in this jig is
8 by 12 in. (203.2 by 304.8 mm.), with a piston of equal area.
"With an adjustable dam, the height of discharge may be varied
from 3 to 4.5 in. (76.2 to 114.3 mm.). In order to study the
behavior of the ore-column and bedding during the process of
jigging, one side of the jig-box was made of plate glass. Three
types of strokes were employed: (1) The eccentric, adjustable
within the limits of and 2 in. (0 and 50.8 mm.). (2) Circu-
lar-arc cams, where the period of pulsion occupies three-fourths
of the revolution of the cam, or eccentric shaft, and suction one-
fourth; or by reversing the direction of rotation of the cam-
shaft, or slipping the hub and cam off the shaft and turning it
end for end, the times or periods are reversed respectively for
pulsion and suction. Cams were made having throws up to
2 in. (50.8 mm.), but only the three shortest throws were used
namely, 1 in. (25.4 mm.), 0.5 in. (12.7 mm.), and 0.25 in.
(6.35 mm.). (3) Involute cams, in which the periods were
divided into thirds, i.e., one-third of the revolution of the cam-
shaft devoted to pulsion, and two-thirds to suction ; or as noted
above, by reversing the direction of rotation of the cam these
periods were reversed. All cams were made of wood, and
quickly and easily attached to a cast-iron hub, and by means of a
set-screw fastened to the shaft, as shown in full in Fig. 4. Circu-
lar-arc and involute cams indicate the character of the curves.
The circular-arc cams do not give a uniform motion ; or in other
words, the cam in describing equal arcs in either the pulsion-
or suction-period does not cause the piston to travel equal dis-
tances. In the involute cams, however, in either pulsion- or
suction-periods, equal arcs give equal distances for piston-travel.
The manner of communicating motion from the cams or eccen-
tric is clearly indicated in Figs. 1 and 2. These engage with
a brass roller attached to a wrought-iron yoke moving between
vertical guides. In order to steady and support the yoke still
more, a steel rod is attached to the upper end, passing through
a hole in a cross-beam, and is attached to the lower end of the
yoke of the piston-rod. The roller, yoke, and piston are actuated
Adjustable Dam
*18Wrt.Iron
FIG. 1. THE JARVIS LABORATORY- JIG, LONGITUDINAL SECTION AND
ELEVATION, AND PLAN.
DETAILS OF WROUGHT IRON YOKE, ROLLER
AND BRACKET
FIG. 2. THE JAR vis LABORATORY- JIG, END ELEVATION AND SECTION, AND
DETAILS OF YOKE, ETC.
INVESTIGATION ON JIGGING.
15
positively by the cam on the up-stroke, aud to secure a strong
and quick down-stroke, a spring of 60 Ib. pressure per linear
inch of compression was employed. This elastic pressure
insured a uniform contact of the roller and cam. It is evi-
dent that a large number of styles of cam-curves may be used
DETAILS OF REMOVABLE JIG BOX, BOX MADE OF No.24 GAL. IRON
DETAIL OF ECCENTRIC
KEY
FIG. 3. THE JARVIS LABORATORY- JIG, DETAILS OF JiG-Box AND ECCENTRIC.
with this device, and the period of movement of the piston
may be varied almost infinitely. It is to be observed, also, that
in this system the piston, in all positions, is perfectly hori-
zontal. The piston is made of a single piece of sole-leather,
securely riveted between two heavy plates of galvanized iron.
With these materials the piston can be run with very little
16
INVESTIGATION ON JIGGING.
CAM WITH 1 IN. THROW
CAM WITH X IN. THROW
REAR ELEVATION
VERTICAL SECTION
THROUGH A-B
DETAIL OF CAM HUB
FIG. 4. THE JABVIS LABORATORY- JIG, ELEVATIONS AND SECTIONS OF
CIRCULAR-ARC WOODEN CAMS.
clearance, and there is no danger of warping, swelling, or get-
ting out of repair very easily. The hutch-box sloped from three
INVESTIGATION ON JIGGING.
17
sides, at an angle exceeding 50, to a single spigot in one side
of the jig. It was found that at this angle little or no hutch-
work collected on the sides, and its entire removal was easily
effected. The jig was driven by a 1-h.p. electric motor through
the variable-speed counter-shaft. The sieve was supported in
a galvanized-iron skeleton, which was removable from the jig-
box itself, and different sized screens could readily be inter-
INVOLUTE,^ IN.
INVOLUTE, 2 IN.
INVOLUTE, \X IN. INVOLUTE, 1 IN.
FIG. 5. THE JABVIS LABORATORY- JIG, CORVES OF INVOLUTE CAMS.
changed. In the tests hereinafter described, only one size
sieve an 8-mesh one was used.
2. Materials and Other Accessories.
A. Screens. Table II. gives the number and mesh of the
screen, and the size of the aperture in inches and millimeters.
In all cases the holes were square. The size of the hole in the
first five sizes was determined by measuring the wire^with a wire-
18
INVESTIGATION ON JIGGING.
gauge, and counting the number of meshes in a given length.
For the remaining screens the diameter of hole was determined
by measuring the diameter of the wire and the aperture with a
microscopic micrometer, each value given being the mean of
several determinations.
B. Sieve-Sizes. The data pertaining to the sieve-sizes are
given in Table II.
TABLE II. Sieve-Sizes.
No.
Mesh.
Kind.
Size of Aperture.
1
4
6
8
10
12
20
40
60
80
100
Brass.
Brass.
Brass.
Steel.
Brass.
Brass.
Brass.
Brass.
Brass.
Brass.
Inch.
0.2097
0.1882
0.0966
0.0841
0.0654
0.0381
0.0165
0.0102
0.0082
0.0063
Mm.
5.326
3.510
2.453
2.136
1.661
0.970
0.420
0.260
0.210
0.160
2
3
4
5
6
7
8
9
10
Jig-Sieve.
Steel.
0.097
2.464
C. Bedding. The bedding used in all the following tests was
sized between the limits of 3.510 and 5.326 mm., or through
the 4-mesh sieve and on the 6-mesh sieve, and was maintained
at the same thickness, 1.5 in. (38.1 mm.), upon the jig-sieve
throughout the experiments.
D. Minerals. The three minerals used were fairly pure.
The quartz was kindly furnished by Professor Munroe, and the
sphalerite and galena by the Foote Mineral Co., of Philadel-
phia, Pa.
E. Specific Gravities. The specific gravity of each mineral
was: galena, 6.66; sphalerite, 3.74; and quartz, 2.62.
The low specific gravity of the two metallic minerals indi-
cates that they are not pure, and an examination revealed the
presence of included quartz and minute quantities of other min-
erals. In crushing these minerals, all the quartz particles that
could be picked out by hand were removed. The values given,
however, are those obtained for the crushed minerals, ready to
be added to the feed.
These three minerals were selected since zinc-blende and
galena represent about the minimum and maximum limits
INVESTIGATION ON JIGGING.
19
respectively of the ores usually treated on jigs. In thus exam-
ining the two limits, the behavior of intermediate minerals
could be closely predicted.
F. Feed. The feed in all the tests was crushed by stages
until small enough to pass the lO-mesh (2.136 mm.) screen.
This size represented the maximum, from which it varied to
that of the finest dust. Two classes of feed were employed.
The first contained 10 per cent., by weight, of heavy mineral
(galena or blende), and the second 20 per cent, of heavy min-
eral. The balance was, respectively, 90 or 80 per cent, of
quartz. Table III. shows the screen-analysis of the three min-
erals constituting the feed.
TABLE III. Screen-Analysis of Minerals in Feed.
All through 10-mesh
(2.136 mm.), and Through.
on, mesh, ... 12. 20. 40. 60. 80. 100. 100.
On, mm., .... 1.66 0.97 0.42 0.26 0.21 0.16 0.16
Per
Per
Per
Per
Per
Per
Per
Mineral.
Cent.
Cent.
Cent.
Cent.
Cent.
Cent.
Cent.
Total.
Galena, . . .
. . 9.6
23.1
26.3
10.8
5.4
2.8
21.2
99.2
Sphalerite, . .
. . 10.5
24.5
26.8
10.5
5.4
2.9
18.6
99.4
Quartz, . . .
. . 17.1
29.1
26.4
7.5
4.5
2.3
11.0
99.0
The values in Table III. represent the mean of three or four
different determinations, made after crushing a large lot and
thoroughly sampling it down.
Table IV. shows the calculated percentages of galena and
quartz in the two classes of feed, based upon the screen-analysis
of the pure minerals given in Table III.
TABLE IV. Analyses of Ten- and Twenty-Per Cent.
Galena Feed.
Ten-Per Cent. Galena Feed.
M - h -{
12.
1 66
20.
97
40.
42
60.
26
80.
21
100.
16
Thro'
100.
16
Average.
Quartz
Galena
Per Ct.
94.1
5.9
Per a.
92.0
8.0
Per Ct.
90.0
10.0
Per Ct.
88.8
11.2
Per Ct.
88.2
11.8
Per Ct.
88.1
11.9
Per Ct.
82.3
17.7
Per Ct.
89.1
10.9
Twenty-Per Cent. Galena Feed.
Quartz
Per Ct.
87.7
Per Ct.
83 4
Per Ct.
80.0
Per Ct.
77.7
Per Ct.
77.3
Per Ct.
76.8
Per Ct.
67.7
Per Ct.
78.7
Galena
12.3
16.6
20.0
22.7
22.3
23.2
32.3
21.3
20
INVESTIGATION ON JIGGING.
The results obtained for sphalerite and quartz are given in
Table V.
TABLE V. Analyses of Ten- and Twenty-Per Cent.
Sphalerite Feed.
Ten-Per Cent. Sphalerite Feed.
Thro'
r i nc h.
12.
20.
40.
60.
80.
100.
100.
Average.
jyjCS.n. *\ Tyim
1 66
97
0.42
26
21
0.16
0.16
Per Ct.
Per Ct.
Per Ct.
Per Ct.
Per Ct.
Per Ct.
Per Ct.
Per Ct.
Quartz
93.6
91.5
90.0
89.2
88.3
87.7
84.6
89.3
Sphalerite
6.4
8.5
10.0
10.8
11.7
12.3
15.4
10.7
Twenty-Per Cent. Sphalerite Feed.
Quartz
Per Ct.
86.7
Per Ct.
82.7
Per Ct.
80.0
Per Ct.
78.3
Per Ct.
77.0
Per Ct.
75.9
Per Ct.
70.4
Per Ct.
78.7
Sphalerite
13.3
17.3
20.0
21.7
23.0
24.1
29.6
21.3
In Tables IV. and V. the columns for each of the respective
feeds show the percentages of each of the two minerals on the
different screen-sizes. Thus, in Table IV., with 10 per cent, of
galena, the stuff resting on the 12-mesh (1.66 mm.) sieve con-
tained 94.1 per cent, of quartz and 5.9 per cent, of galena, etc.
With both sphalerite and galena, the screen-analyses, and
from these the calculated percentages of the mineral-content of
each screen-size, show that more fine material is produced in
crushing these softer minerals than in crushing quartz. The
finest size of the 10 and the 20 per cent, galena or sphalerite
shows a much higher percentage of these minerals than the
average of the feed, as shown in Tables IV. and V.
3. Method of Conducting the Tests.
In beginning a series of tests on a given feed, the exact pro-
portion of each mineral was weighed out, so that the total
quantity was 35 Ib. (15.87 kg.). Meanwhile, the sieve had
received its bedding, 1.5 in. (38.1 mm.), and the hutch-box
and jig were filled with water; the tailings-trough placed in
position, connecting with a large tub in which all the overflow
and tailings were caught ; the feed thoroughly wetted down (it
fresh material) ; power was turned on and the jig started. In
case it was the first run of a series, the jig-box containing bed-
ding only, the feed was rapid until this was filled with the mix-
ture, after which the feeding proceeded at the regular rate.
INVESTIGATION ON JIGGING. 21
The feeding was accomplished by filling with the ore-mixture
a large flat-bottomed scoop, of a width slightly less than that
of the jig-compartment, 8 in. (203.2 mm.), and with a small
and constant stream of water washing the material from the
scoop on to the jig. While the speed of jigging and the rate
of feeding varied, the object always aimed at was to feed the
jig just as fast as it appeared able to treat the material. The
discharge was watched constantly to see if any particles of
heavy mineral were being carried into the tailings. If so, the
rate of feeding was reduced. Close watch was also kept on the
jig-bed, and if the jig showed symptoms of clogging up, due
to rapid feeding, the rate of feed was immediately decreased.
At the end of the run, usually from 8 to 15 min., the jig
was stopped, the water-supply cut off, and the hutch-products
drawn off' into suitable vessels. After allowing the material to
settle, the water was carefully decanted and the products
thoroughly mixed, and a sample of about 125 g. cut out, which
was dried, and later exactly 100 g. of this sample was weighed
out on a pulp-balance and sized on a nest of sieves, ranging
from 12-mesh (1.66 mm.) through 100-mesh (0.16 mm.), and
each size carefully weighed ; finally, the percentage of galena
or sphalerite in each sieve-size was determined. The analyses
of the products were made in several ways. In the first two
or three coarse sizes good results were obtained by weighing
out 1 or 2 g. and picking out the quartz or other mineral by
hand and then weighing again ; also, by comparing with
standard mixtures of quartz and galena or sphalerite. In the
small sizes vanning-tests were made.
After the completion of a run, the tailings, which were given
ample time in which to allow the fine material to settle and
the water to be decanted off", were again mixed with the
product from the hutch and formed the feed for another test.
The material was thus used repeatedly until all the tests had
been completed for a particular series or class. The material
remaining in the jig-box was not cleaned out from test to test,
unless another feed was to be employed. The investigations
had to do only with what passed into the hutch, and deter-
minations upon the character and nature of what remained on
the sieve, except as it could be examined through the glass
side of the jig, were not made.
22 INVESTIGATION ON JIGGING.
4. Record of Results.
In the following records are five horizontal rows of figures :
in the topmost row, the sieve-mesh; in the next lower row, the
corresponding size in millimeters of the aperture upon which
the material was caught ; and three lower rows marked " A"
" _B," and " C" respectively. The first of these, A, gives the
weights in grams of the different sieve-sizes ; and since these
are all on a basis of 100 g. the weights, therefore, represent
percentages as well. Row B gives the percentage of heavy
mineral, galena or sphalerite, in each of the sieve-products, and
the balance in every case is quartz. Row C gives the weight
of heavy mineral contained in each of the sieve-sizes, and is
obtained by multiplying the weights in row A by the respective
percentages in the B row. The sum of the products in the C
row gives the number of grams of mineral in 100 g. of the con-
centrate, or in other words, the percentage.
Under the stroke of each experiment are given: (1), the
number of revolutions of the cam or eccentric shaft per minute;
(2) the length in inches and millimeters ; (3) the kind of stroke;
(4) pulsion, in which the fractions , , , f , and refer to the
fractional part of the entire revolution of the cam or shaft in
which this movement took place. The smaller this fraction the
quicker the movement. The rates or velocities are set oppo-
site. The same is true for the period of suction.
The observed pulsion- and suction-velocities noted in the fol-
lowing tests and elsewhere in this paper are to be understood as
the mean piston-velocities, or the velocities of the water-column
in the free part of the jig-column, and not the actual current-
velocities acting upon a mass of grains constituting the jig-bed.
In studying these experiments, reference should be made to
Figs. 6 to 13, inclusive, in which row C is shown graphically
representing the mean diameter of grains.
TEST I. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min.. 160. Length, 1 in. (25.4 mm.).
Pulsion
Suction
Kind:
: i (270.7mm.)
: f ( 90.2mm.)
Circular-arc cam.
= 10.66 in. per sec.
= 3.55 in. per sec.
On mesh
Size in mm..
12. 20.
1.66 0.97
40. 60. 80.
0.42 0.26 0.21
100. thro' 100.
0.16 0.16
Total.
A. 3.3 11.6
B. 100.0 80.0
C. 3.3 9.3
36.0 18.4 9.5
35.0 20.0 15.0
12.6 3.7 1.4
4.7
20.0
0.9
16.0
28.0
4.5
99.5
35.7
INVESTIGATION ON JIGGING. 23
Percentage of galena in concentrates : 35.7.
Katio of concentration based on original feed: 3.57.
Remarks. All the material on the jig-bed pulsated the material above having
a longer amplitude than the grains deeper down. It was observed that the bedding-
grains at the top moved nearly 0.75 in. vertically, while those at the bottom of the
bed next to the screen moved about 0.25 in.
TEST 2. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Circular-arc cam.
Pulsion : f ( 90.2 mm.) = 3.55 in. per sec.
Suction: j (270.7 mm.) == 10.66 in. per sec.
On mesh i 12.
Size in mm..ll.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
0.7
100.0
0.7
7.0
95.0
6.6
26.5
60.0
15.9
22.2
35.0
7.7
14.0
25.0
3.5
6.6
20.0
1.3
22.3
30.0
6.7
99.3
42.4
Percentage of galena in concentrates : 42.2.
Ratio of concentration based on original feed : 4.24.
Remarks. Some movement of the bedding-grains, especially near the top, but
only a few grains of galena were visible in the interstitial spaces of the bedding.
The ore-column pulsated violently, and between the bedding and the ore was a
zone in very active motion, while above the column of ore was quite compact.
TEST 3. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Involute cam.
Pulsion : (203.2 mm.) = 8 in. per sec.
Suction : 3 (101.6 mm.) = 4 in. per sec.
On mesh..
Size in mn
...1 12.
i.Jl.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
2.4
95.0
2.3
12.7
75.0
10.5
35.6
25.0
8.0
18.0
16.0
3.0
10.3
15.0
1.5
5.6
15.0
0.8
14.7
20.0
2.0
99.3
29.9
Percentage of galena in concentrates : 29.9.
Ratio of concentration based on original feed : 2.99.
Remarks. The bedding and with it the ore-column pulsated. The grains of
bedding were kept in constant circulation. Very few grains of galena could be
seen in the interstitial spaces of the bedding, but were free. It was evident, there-
fore, that if a galena- or quartz-grain got as far as the bedding it had little oppor-
tunity of remaining there. '
TEST 4. Galena 10, Quartz 90 per cent.
Stroke: Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Involute cam.
Pulsion : $ (101.6 mm.) = 4 in. per sec.
Suction : (203.2 mm.) = 8 in. per sec.
On
Size
mesh
in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 0.4
B. 60.0
C. 0.2
7.8
50.0
3.9
39.7
25.0
9.9
21.4
22.0
4.7
10.7
18.0
1.9
4.7
18.0
0.8
14.8
22.0
3.2
99.5
24.6
24 INVESTIGATION ON JIGGING.
Percentage of galena in concentrates : 24.6.
Katio of concentration based on original feed : 2.46.
Remarks. The ore-bed pulsated violently, but not so much so as with the
strong suction of the circular-arc cam in Test 3. The grains of the bed did not
behave exactly alike, and the middle of the bed contained some grains of galena.
TEST 5. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm,).
Kind : Eccentric.
Pulsion and Suction : } (135.5 mm.) = 5.33 in. per sec.
On mesh | 12.
Size in mm.. 1 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
1.4
95.0
1.3
9.0
95.0
8.5
34.0
35.0
11.9
20.5
20.0
4.1
11.7
20.0
2.3
6.0
20.0
1.2
17.2
28.0
4.8
99.8
34.1
Percentage of galena in concentrates : 34.1.
Eatio of concentration based on original feed : 3.41.
Remarks. The entire bed pulsated much more uniformly than in Tests 3 and 4.
The bedding-grains were free to move, and tended to move in convection-currents.
No particles of galena collected on top of the bedding, and few could be seen in
the interstitial spaces.
TEST 6. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Eccentric.
Pulsion and Suction : (67.7 mm.) = 2.66 in. per sec.
On mesh
Size in mm..
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
2.7
95.0
2.5
26.8
78.0
20.9
20.7
48.0
9.9
13.2
33.0
4.3
10.0
27.0
2.7
26.2
38.0
9.9
99.6
50.2
Percentage of galena in concentrates : 5.02.
Ratio of concentration based on original feed : 50.2.
Remarks. The lower third of bedding quite fixed, while the upper two-thirds
pulsated, but the grains did not change positions moving en masse. The ore-
column pulsated regularly, and between the beddingand the ore was a zone of great
mobility. The action and movement going on in the ore-column resembled very
much that taking place in a hydraulic classifier.
TEST 7. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Circular-arc cam.
Pulsion : J (135.5 mm.) = 5.33 in. per sec.
Suction : f ( 45.2 mm.) = 1.77 in. per sec.
On mesh....j 12.
Size in mm..ll.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
0.8
100.0
0.8
6.4
97.0
6.2
24.7
60.0
14.8
21.4
35.0
7.5
13.2
18.0
2.3
7.5
20.0
1.5
26.0
27.0
7.0
100.0
40.1
INVESTIGATION ON JIGGING. 25
Percentage of galena in concentrates : 40.1.
Ratio of concentration based on original feed : 4.01.
Remarks. The bedding and the ore-column pulsated uniformly the top having
a longer amplitude and extending over a longer time than the grains nearer the
bottom. Ore-column very mobile and in active circulation. The upper third of
bedding contained many particles of galena.
TEST 8. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, i in. (12.7 mm.).
Kind : Circular-arc cam.
Pulsion : ( 45.2 mm.) = 1.77 in. per sec.
Suction : } (135.5 mm.) = 5.33 in. per sec.
On mesh...
Size in mm
.112. 20.
..11.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
C.
2.1
90.0
1.9
26.0
53.0
13.8
24.4
31.0
7.5
14.7
20.0
2.9
7.1
20.0
1.4
25.3
27.0
6.8
99.6
34.3
Percentage of galena in concentrates : 34.3.
Ratio of concentration based on original feed : 3.43.
Remarks. Only the top third of bedding showed any signs of movement, but
the interstitial spaces were filled with particles of galena. The particles in the
ore-column tended to circulate in two opposite and distinct paths.
TEST 9. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Involute cam.
Pulsion : (101.6 mm.) = 4 in. per sec.
Suction : f ( 50.8 mm.) = 2 in. per sec.
On mesh....: 12.
Size in mm.. 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 1.3
B. 100.0
C. 1.3
10.3
100.0
10.3
27.9
72.0
20.0
20.5
31.0
6.3
11.9
22.0
2.6
6.4
20.0
1.3
21.2
31.0
6.5
99.5
48.3
Percentage of galena in concentrates : 48.3.
Ratio of concentration based on original feed : 4.83.
Remarks Both the bedding and the ore-column pulsated the top having a
longer amplitude of vibration and requiring a longer time than the grains nearer
the bottom. Many grains of galena in the upper third of bedding and decreasing
below. The ore-column very mobile, and line between bedding and ore hori-
zontal and uniformly even.
TEST 10. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Involute cam.
Pulsion : $ ( 50.8 mm.) = 2 in. per sec.
Suction : J (101.6 mm.) = 4 in. per sec.
On mesh....j 12.
Size in mm..|1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A
B
C.
1.0
90.0
0.9
26.4
70.0
20.5
25.1
30.0
7.5
13.7
2^.0
3.8
7,2
26.0
1.8
26.5
32.0
8.5
99.9
43.0
26 INVESTIGATION ON JIGGING.
Percentage of galena in concentrates : 43.0.
Ratio of concentration based on original feed : 4.30.
Remarks. The bedding-grains were practically stationary neither pulsation
nor movement among themselves, and were filled with particles of galena. The
ore-column pulsated, but was not mobile except for a zone 0.5 in. teick on top of
the bedding. Evidently too much suction.
TEST 11. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, \ in. (6.35 mm.).
Kind : Involute cam.
Pulsion : (50.8 mm.) = 2 in. per sec.
Suction : (25.4 mm.) = 1 in. per sec.
On mesh...
Size in mm.
.( 12. 20.
J1.68 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
2.4
95.0
2.3
24.1
92.0
22.1
20.0
56.0
11.2
16.3
35.0
5.7
9.4
22.0
2.0
27.8
25.0
5.7
100.0
49.0
Percentage of galena in concentrates : 49.0.
Ratio of concentration based on original feed : 4.90.
Remarks. The bedding, as a whole, did not pulsate, but the grains in the
upper part of the bedding showed some movement, and this portion was filled
with particles of galena. The ore-column was very mobile and pulsated regu-
larly and uniformly. The large grains of quartz rested directly upon the bed-
ding, with the finer quartz-particles above.
TEST 12. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, J in. (6.35 mm.).
Kind : Involute cam.
Pulsion : f (25.4 mm.) = 1 in. per sec.
Suction : J (50.8 mm.) = 2 in. per sec.
On mesh....
Size in mm...
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
1.4
80.0
1.1
20.4
62.0
12.6
24.5
40.0
9.8
18.8
27.0
5.0
9.1
24.0
2.2
25.5
25.0
6.3
99.7
37.0
Percentage of galena in concentrates : 37.0.
Ratio of concentration based on original feed : 3.7.
Remarks The bedding did not move at all. The ore-bed seemed to be quite
mobile immediately above the bedding, but compact close to the top.
TEST 13. Galena 10, Quartz 90 per cent.
Stroke: Cam-shaft rev. per min., 160. Length, \ in. (6.35 mm.).
Kind : Circular-arc cam.
Pulsion : \ (67.7 mm.) = 2.66 in. per sec.
Suction : (22.5 mm.) = 0.88 in. per sec.
On mesh....
Size in mm..
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total
A.
B.
C.
4.2
95.0
4.0
24.8
62.0
15.3
25.5
26.0
6.6
15.1
20.0
3.0
7.3
18.0
1.3
23.1
27.0
6.3
100.0
36.5
INVESTIGATION ON JIGGING. 27
Percentage of galena in concentrates : 36.5-
Katio of concentration based on original feed : 3.65.
Kemarks. The bedding and the ore-column pulsated, but the grains of bedding
were not sufficiently mobile to rearrange themselves, although the upper third was
much more mobile and pulsated much more than the bottom, and many particles
of galena were contained in the interstitial spaces of the upper third of bedding.
The entire ore-column was very free and mobile and pulsated uniformly.
TEST 14. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, \ in. (6.35 mm.).
Kind : Circular-arc cam.
Pulsion : (22.5 mm.) = 0.88 in. per sec.
Suction : J (07.7 mm.) = 2.66 in per sec.
On mesh....
Size in mm..
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
C.
2.0
94.0
2.0
24.6
62.0
15.2
22.6
25.0
4.6
14.4
20.0
2.9
7.0
22.0
1.5
29.4
33.0
9.7
100.0
35.9
Percentage of galena in concentrates : 35.9.
Eatio of concentration based on original feed : 3.59.
Remarks. No movement in the bedding, although the top bedding-grains
showed some tendency to move, and many particles of galena could be seen in the
upper third of the bedding. The ore-column pulsated regularly, and was quite
compact
TEST 15. Galena 10, Quartz 90 per cent.
Stroke :
Pulsion
Cam-shaft rev. per min., 160. Length, \ in. (6.35 mm.).
Kind : Eccentric,
and Suction : (33.9 mm.) = 1.33 in. per sec.
On mesh
Size in mm..
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro
0.16
'100.
0.16
Total.
A.
B.
a
0.4
85.0
0.3
17.8
63.0
11.2
23.9
31.0
7.4
17.2
20.
3.4
9.3
20.0
1.8
31.0
30.0
9.3
99.6
33.4
Percentage of galena in concentrates : 33.4.
Eatio of concentration based on original feed : 3.34.
Eemarks. The bedding was quite fixed in position, and the upper part well
filled with grains of galena. It was noticed that when the feed was too fast, an in-
clined line, beginning at the top of the bedding at the back of the jig-box, and
sloping up nearly to the top of the ore-column at the front or discharge was
formed. Otherwise the ore-column was mobile, with the coarse particles of quartz
resting above the bedding, and the finer particles arranged above.
TEST 16. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 320. Length, J in. (6.35 mm.).
Kind : Eccentric.
Pulsion and Suction: | (57.7 mm.) = 2.66 in. per sec.
On mesh 12. 20. 40. 60. 80 100. thro' 100. Total.
Size in mm.. 1.66 0.97 0.42 0.26 0.21 0.16 0.16
A. 0.8 6.4 31.5 26.9 11.9 5.8 16.4 99.7
B. 100.0 98.0 60.0 25.0 15.0 20.0 30.0
C. 0.8 6.4 18.9 6.7 1.8 1.1 4.9 40.6
28 INVESTIGATION ON JIGGING.
Percentage of galena in concentrates : 40.6.
Katio of concentration based on original feed : 4.06.
Kemarks. Both the bedding and the ore-column pulsated regularly the grains
near the top of the bedding having a longer, amplitude of vibration than those near
the bottom, and the same being true of the grains in the ore-column. The ore-
column was very mobile. The jig worked fast.
TEST 17. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 320. Length, in. (3.17 mm.).
Kind : Eccentric.
Pulsion and Suction : (33.9 mm.) = 1.33 in. per sec.
On mesh
Size in mm..
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
4.2
31.3
27.2
13.5
6.4
17.4
100.0
B.
95.0
35.0
21
.0
18.0
18.0
28.0
a
4.0
10.9
5.7
2.4
1.1
4.9
29.0
Percentage of galena in concentrates : 29.0
Ratio of concentration based on original feed : 2.90.
Kemarks. The entire bed pulsated, and the bedding contained many particles
of galena and some quartz. As noted before, the top had a longer amplitude of
vibration than the bottom, and required a longer time. The ore-column pulsated
regularly, and the fine material (quartz) was carried down to the bedding so that
it was distributed quite regularly throughout the ore. The ore-column was
compact.
TEST 18. Galena 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 400. Length, ^ in. (1.59 mm.).
Kind : Eccentric.
Pulsion and Suction : (21.2 mm.) = 0.83 in. per sec.
On mesh 12. 20.
Size in mm.. 1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A 2.6
37.3
26.0
12.1
5.8
16.1
99.9
B 100.0
25.0
23.0
16.0
15.0
26.0
a 2.6
9.3
6.0
1.9
0.8
4.2
24.8
Percentage of galena in concentrates : 24.8.
Ratio of concentration based on original feed : 2.48.
Remarks. The grains of the bedding were not very mobile, and only the top
layer of grains showed any indication of pulsating. The base of the ore-column
was distinguished by a zone of active agitation. Above this zone, which was only
0.5 in. thick, the ore-column was compact and not mobile. The bedding-grains
contained only a few galena-grains in the upper third portion, but the interstitial
spaces were filled with quartz. In the middle and lower third portions of the
bedding, many more grains of galena were visible, being more abundant in the
middle third.
INVESTIGATION ON JIGGING. 29
TEST 21. Galena 20, Qwarte 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1
Kind : Circular-arc cam.
Pulsion : } (270.7 mm.) = 10.66 in. per sec.
Suction : f ( 90.2 mm.) = 3.55 in. per sec.
in. (25.4 mm.).
On mesh 1 12. 20. 40. 60. 80.
Size in mm.. 1.66 0.97 0.42 0.26 0.21
100. thro' 100.
0.16 0.16
Total.
A. 4.3 18.1 33.2 16.7 8.5
S. 100.0 90.0 55.0 50.0 40.0
C. 4.3 16.2 18.1 8.5 3.4
4.0 14.8
40.0 50.0
1.6 7.5
99.6
59.6
Percentage of galena in concentrates : 59.6.
Ratio of concentration based on original feed : 2.98.
Remarks. Movement of jig-bed same as Test 1.
TEST 22. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1
Kind : Circular-arc cam.
Pulsion : f (90.2 mm) = 3.55 in. per sec.
Suction : J (270.7 mm.) = 10.66 in. per sec.
in. (25.4mm.).
On mesh 12. 20. 40. 60. 80.
Size in mm.. 1.66 0.97 0.42 0.26' 0.21
100. thro' 100.
0.16 0.16
Total.
A. 0.5 6.6 30.4 19.6 11.5
B. 100.0 90.0 65.0 55.0 45.0
C. 0.5 5.9 19.5 11.0 5.1
5.6 25.7
45.0 50.0
2.5 12.8
99.9
57.3
Percentage of galena in concentrates : 57.3.
Ratio of concentration based on original feed : 2.86.
Remarks. Movement of jig-bed similar to Test 2.
TEST 23. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1
Kind : Involute cam.
Pulsion : J (203.2 mm.) = 8 in. per sec.
Suction : f (101.6 mm.) = 4 in. per sec.
in. (25.4 mm.).
On mesh 12. 20. 40. 60. 80.
Size in mm.. 1.66 0.97 0.42 0.26 0.21
100. thro' 100.
0.16 0.16
Total.
A. 3.4 16.5 32.4 18.0 9.2
B. 100.0 95.0 55.0 40.0 40.0
C. 3.4 15.6 17.6 7.2 3.6
4.3 15.6
40.0 45.0
1.6 7.0
99.4
56.0
Percentage of galena in concentrates : 56.0.
Ratio of concentration based on original feed : 2.80.
Remarks. Movement of bed similar to Test 3.
30 INVESTIGATION ON JIGGING.
TEST 24. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
. Kind : Involute cam.
Pulsion : (101.6 mm.) = 4 in. per sec.
Suction : (203.2 mm.) = 8 in. per sec.
On mesh....
Size in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 1.5
B. 95.0
a 1.4
12.2
80.0
9.6
34.0
56.0
18.7
20.0
45.0
9.0
10.2
40.0
4.0
4.8 17.5
45.0 45.0
2.1 7.7
100.2
52.5
Percentage of galena in concentrates : 52.5.
Ratio of concentration based on original feed : 2.62.
Eemarks. The entire bed pulsated, but not so violently as No. 23. The ore-
column pulsated much more than the bedding, and the top of the bedding than the
bottom. Between the bedding and the ore-column was a zone 0.5 in. thick of
great activity. Few grains in the interstitial spaces of the bedding. Jigged
rapidly.
TEST 25. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Eccentric.
Pulsion and Suction : (135.5 mm.) = 5.33 in. per sec.
On mesh....
Size in mm..
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
4.6 17.4
28.8
17.1
9.5
5.5
17.2
100
1
B. 100.0 95.0
80.0
50.0
40.0
50.0
45.0
a
4.6 17.0
23.7
8.5
3.8
2.2
7.6
67
4
Percentage of galena in concentrates : 67.4.
Ratio of concentration based on original feed : 3.37.
Remarks. The entire bed pulsated, the upper part having a longer amplitude
of vibration and requiring a longer time to complete it than the grains nearer the
bottom. Difficult to save the finest grains of galena. The bedding-grains were
free to change positions during the pulsion-cycle.
TEST 26. Galena 20, Quartz 80 per cent.
Stroke: Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind: Eccentric.
Pulsion and Suction : $ (67.7 mm.) = 2.66 in. per sec.
On
Size
mesh....
in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 0.7
B. 100.0
C. 0.7
7.3
100.0
7.3
26.0
85.0
22.1
16.9
60.0
10.2
11.7
45.0
5.4
7.4
40.0
2.8
29.5
40.0
12.0
99.5
60.5
Percentage of galena in concentrates : 60.5
Ratio of concentration based on original feed : 3.02.
Remarks. The entire bed pulsated, and the zone between the bedding and the
INVESTIGATION ON JIGGING. 31
ore-column was an active one the grains in the ore-column were kept in constant
circulation. The interstitial spaces in the upper third of the bedding filled with
particles of galena.
TEST 27. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Circular-arc cam.
Pulsion : | (135.5 mm.) = 5.33 in. per sec.
Suction: f ( 45.2 mm.) = 1.77 in. per sec.
On mesh.
Size in mt
... 12.
n.. 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
2.4
100.0
2.4
15.0
100.0
15.0
27.9
85.0
23.8
18.4
50.0
9.2
11.4
35.0
3.8
6.0 18.7
35.0 35.0
2.1 6.6
99.8
62.9
Percentage of galena in concentrates : 62.9.
Ratio of concentration based on original feed : 3.15.
Eemarks. The entire bed pulsated very uniformly, the top having a longer
time to complete it than the grains nearer the bottom. Many grains of galena in
the upper part of the bedding, but only a few in the lower half.
TEST 28. Galena 20, Quartz SO per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Circular-arc cam.
Pulsion : f ( 45.2 mm.) = 1.77 in. per sec.
Suction : (135.5 mm.) = 5.33 in. per sec.
On mesh....] 12.
Size in mm.. 1 1.66
20.
0.97
40.
0.42
HO.
0.26
80.
0.21.
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
0.1
100.0
0.1
1.7
95.0
1.7
25.0
85.0
21.2
22.0
bO.O
13.2
12.7
45.0
5.8
7.3
45.0
3.1
31.2
45.0
13.9
100.0
59.0
Percentage of galena in concentrates: 59.0.
Ratio of concentration based on original feed : 2.95.
Remarks. The bedding-grains did not pulsate, although those near the top
exhibited a slight tendency. The ore-column pulsated, but excepting a zone about
0.5 in. thick immediately above the bedding was otherwise compact. The ore-
grains circulated in two distinct and opposite paths.
TEST 29. Galena 20, Quartz 80 per cent.
Stroke: Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Involute cam.
Pulsion : (101.6 mm.) = 4 in. per sec.
Suction : 5 ( 50.8 mm.) = 2 in. per sec.
On mesh.... 12. 20. 40. 60. 80. 100. thro' 100. Total.
Size in mm.. 1.66 0.97 0.42 0.26 0.21 0.16 0.16
Z 374 16^0 25! 17^2 1L2 6^2 2O7 99^8
B. 1UO.O 100.0 85.0 60.0 45.0 40.0 45.0
C. 3.4 16.0 21.2 10.2 4.9 2.4 9.4 67.5
32 INVESTIGATION ON JIGGING.
Percentage of galena in concentrates : 67.5.
Katio of concentration based on original feed : 3.37.
Remarks. The entire bed pulsated, the upper part, as noted before, having a
longer amplitude of vibration and requiring a longer time to complete it than the
grains beneath. The upper half of the bedding contained many particles of galena,
while only a few were visible in the lower half.
TEST 30. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Involute cam.
Pulsion: f ( 50.8 mm.) = 2 in. per sec.
Suction : J (101.6 mm. ) = 4 in. per sec.
On mesh.... 12. 20. 40. 60. 80. 100. thro' 1 00. Total.
Size in mm. .1.66 0.97 0.42 0.26 0.21 0.16 0.16
A. 0.1 3.0 31.3 21.6 11.5 6.5 25.7 99.7
B. 100.0 95.0 65.0 50.0 40.0 40.0 45.0
C. 0.1 2.8 20.1 11.0 4.8 2.6 11.7 53.1
Percentage of galena in concentrates : 53.1.
Katio of concentration based on original feed : 2.65.
Kemarks. The bedding exhibited a slight tendency to pulsate en masse. The
upper part of the bedding well filled with particles of galena, decreasing rapidly
in number below. Immediately above the bedding the ore-column presented a
zone of active agitation about 0.5 in. thick, while above the particles seemed quite
compact and not very mobile.
TEST 31. Galena 20, Quartz 80 per cent.
Stroke: Cam-shaft rev. per min., 160. Length, J in. (6.35 mm.).
Kind : Involute cam.
Pulsion : J (50.8 mm.) = 2 in. per sec.
Suction : f (25.4 mm.) = 1 in. per sec.
On mesh....| 12.
20.
40.
60.
80.
100. thro' 100.
Total.
Size in mm..|1.66
0.97
0.42
0.26
0.21
0.16 0.16
A
1.4
23.0
17.0
14.6
9.0 35.0
100.0
B
100.0
100.0
85.0
60.0
50.0 45.0
C.
1.4
23.0
14.4
8.7
4.5 15.7
67.7
Percentage of galena in concentrates: 67.7.
Eatio of concentration based on original feed : 3.39.
Kemarks. The upper one-third of the bedding-grains exhibited some tendency
to arrange themselves during pulsion, but the lower two-thirds did not move or
pulsate. In the upper third were many particles of galena and less below. The
ore-column pulsated regularly, the large grains of quartz arranging themselves
next to the bedding, the smaller on top. The ore-column was mobile.
INVESTIGATION ON JIGGING.
TEST 32. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev.
Kind
Pulsion: (25.4 mm.) =
Suction: J (50.8 mm.) =
per min., 160. Length, J in. (6.35 mm.).
: Involute cam.
= 1 in. per sec.
= 2 in. per sec.
On mesh....| 12.
Size in mm..)1.66
20.
0.97
40. 60. 80.
0.42 0.26 0.21
100. thro' 100.
0.16 0.16
Total.
A
B
a
1.2
90.0
1.1
17.5 26.3 15.4
90.0 55.0 40.0
15.7 14.3 6.0
8.7 30.7
35.0 40.0
3.1 12.4
99.8
52.6
Percentage of galena in concentrates : 52.6.
Eatio of concentration based on original feed : 2.63.
Remarks. The bedding did not pulsate. The upper third was filled with par-
ticles of galena and decreasing numbers below. The ore-column was somewhat
mobile in spots, but pulsated quite regularly, and on top of the bedding was a
zone which exhibited considerable activity.
TEST 33. Galena 20, Quartz 80 per cent.
Stroke :
Pulsion
Suction
Cam-shaft rev.
Kind
: J (67.7 mm.)
: f (22.5mm.)
per min., 160. Length, in.
: Circular- a re cam.
= 2.66 in. per sec.
= 0.88 in. per sec.
(6.35 mm.).
On mesh j 12.
Size in mm.. 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100.
0.16
thro' 100.
0.16
Total.
A. 0.4
B. 100.0
a 0.4
5.5
100.0
5.5
27.0
60.0
16.2
24.0
40.0
9.6
13.1
35.0
4.5
6.5
35.0
2.3
23.4
35.0
8.0
99.9
46.5
Percentage of galena in concentrates: 46.5.
Ratio of concentration based on original feed : 2.32.
Eemarks. The upper half and often more of the bedding pulsated. In this
part, also, were many particles of galena. The ore-column was mobile, with the
large quartz-grains arranged near the top of the bedding and the smaller sizes
above.
TEST 34. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev.
Kind:
per min., 160. Length, \ in. (6.35
Circular-arc cam.
mm.).
Pulsion : (22.5 mm.) =
Suction: } (67.7 mm.) =
= 0.88 in. per sec.
= 2.66 in. per sec.
On mesh j 12.
Size in mm..|1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100.
0.16
thro' 100.
0.16
Total.
A.
B
C.
3.0
100.0
3.0
27.7
85.0
23.8
19.2
70.0
13.3
12.3
50.0
6.0
7.2
50.0
3.6
30.5
45.0
13.5
99.9
63.2
Percentage of galena in concentrates : 63.2.
Eatio of concentration based on original feed: 3.16.
Eemarks. The bedding exhibited very little tendency to pulsate, nor was there
34 INVESTIGATION ON JIGGING.
any movement among the grains themselves. The upper half of the bedding was
well filled with grains of galena. The particles of ore above the bedding circu-
lated in two opposite orbits, passing down at the front and back end of jig and
joining in the center.
TEST 35. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, \ in. (6.35 mm.).
Kind : Eccentric.
Pulsion and Suction : (33.9 mm.) = 1.33 in. per sec.
On mesh
Size in mm..
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
99JJ
59.7
A.
B.
a
0.7
95.0
0.7
17.5
95.0
16.6
19.2
70.0
13.3
18.2
45.0
8.1
8.7
45.0
3.5
35.2
40.0
17.5
Percentage of galena in concentrates : 59.7.
Katio of concentration based on original feed : 3.
Kemarks. The bedding pulsated slightly, and the upper half was well filled with
galena, with decreasing quantities below. The ore-column pulsated regularly,
with the largest grains of quartz resting on top of the bedding, decreasing in size
above.
TEST 36. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 320. Length, \ in. (6.35 mm.).
Kind : Eccentric.
Pulsion and Suction : (67. 7 mm.) = 2.66 in. per sec.
On mesh
Size in mm..
12.
1.66
20.
0.97
40.
0.42
KO.
0.26
80.
0.21
100.
0.16
thro' 100.
0.16
Total-
A. 0.6
S. 100.0
C. 0.6
7.2
100.0
7.2
30.1
65.0
19.5
22.8
45.0
10.2
12.3
40.0
4.9
5.6
40.0
2.2
21.2
50.0
10.6
99.8
55.2
Percentage of galena in concentrates : 55 2.
Ratio of concentration based on original feed : 2.76
Kemarks The entire bed pulsated regularly. The upper part of bedding con-
tained many particles of galena.
TEST 37. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 320. Length, in. (3.17 mm.).
Kind : Eccentric.
Pulsion and Suction : (33.9 mm.) = 1.33 in. per sec.
On mesh
Size in mm..
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
C.
10.3
100.0
10.3
27.2
85.0
23.1
23.1
50.0
11.5
13.7
40.0
5.5
7.1
400
2.8
19.0
40.0
7.6
100.4
60.8
Percentage of galena in concentrates : 60.8.
Eatio of concentration based on original feed : 3.04.
Remarks. The upper third of bedding was quite mobile, and filled with parti-
cles of galena, decreasing below. The ore-column seemed quite compact, but pul-
sated regularly.
INVESTIGATION ON JIGGING. 35
TEST 38. Galena 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 320. Length, J in. (12.7 ram.).
Kind : Eccentric.
Pulsion and Suction : J (135.5 mm.) = 5.33 in. per sec.
On mesh
Size in m
.... 12.
m.. 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
4.3
100.0
4.3
16.4
95.0
15.6
34.6
50.0
17.3
18.2
40.0
7.3
9.0
35.0
3.1
4.6
40.0
1.8
13.2
4o.O
5.9
100.3
55.3
Percentage of galena in concentrates : 55.3.
Katio of concentration: 2.76.
Remarks. Both ore and bedding pulsated regularly, but violently. Consider-
able of the finest size of galena could be seen in the tailings. The jig worked
very rapidly.
TEST 41. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min-, 160. Length, 1 in. (25.4 mm.).
Kind : Circular-arc cam.
Pulsion : } (270.7 mm.) = 10.66 in. per sec.
Suction : f ( 90.2 mm.) = 3.55 in. per sec.
On mesh
Size in mm..
12
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100.
0.16
thro' 100.
0.16
Total
A. 11.8
B. 20.0
C. 2.4
31.8
20.0
6.4
30.2
25.0
7.5
11.0
30.0
3.3
5.0
35.0
1.7
2.2
40.0
0.8
5.2
50.0
2.6
97.2
24.7
Percentage of sphalerite in concentrates : 24.7.
Ratio of concentration based on original feed : 2.47.
Remarks The bedding pulsated very violently, and after the jig was stopped
it was found that the surface of the ore-column was 1.5 in. below the tail-
ings-dam.
TEST 42. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Circular-arc cam.
Pulsion: f ( 90.2 mm.) = 3.55 in. per sec.
Suction : j (270.7 mm.) = 10.66 in. per sec.
On mesh
Size in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100.
0.16
thro' 100.
0.16
Total
A. 3.6
B. 60.0
C. 2.1
14.1
65.0
9.1
36.5
35.0
12.7
19.2
30.0
5.7
9.5
35.0
3.3
4.5
30.0
1.4
12.2
40.0
5.0
99.6
39.3
Percentage of sphalerite in concentrates : 39.3.
Ratio of concentration based on original feed: 3.93.
Remarks. The bedding-grains were carried up from bottom to top, circu-
lating in that way as by convection-currents. The ore-column was in active agi-
tation, and the bedding and the ore were not separated by a clearly denned and
horizontal line.
36 INVESTIGATION ON JIGGING.
TEST 43. -Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160 Length, 1 in. (25.4 mm ).
Kind : Involute cam.
Pulsion : J (203.2 mm.) = 8 in. per sec
Suction : f (101.6 mm.) = 4 in. per sec.
On mesh....
Size in mm..
12.
1.66
20.
0.97
40.
0.42
BO.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 7.6
B. 25.0
C. 1.9
26.5
35.0
9.2
34.5
25.0
8.6
13.7
25.0
3.4
6.7
35.0
2.2
3.1
30.0
0.9
8.1
40.0
3.2
100.2
29.4
Percentage of sphalerite in concentrates : 29.4.
Katio of concentration based on original feed : 2.94.
Remarks. The jig-bed pulsated violently. The bedding did not tend to move
in convection-currents, as in Test 42. Between the bedding and the ore-column was
a very active zone 0.5 in wide, in which the mineral particles moved in all direc-
tions and with great rapidity.
TEST 44. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min , 160 Length, 1 in. (25.4 mm.).
Kind : Involute cam.
Pulsion : (101.6 mm.) = 4 in. per sec.
Suction : (203.2 mm.) = 8 in. per sec.
On mesh....l 12.
Size in mm..|1.66
20..
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
0.
3.4
85.0
3.0
17.5
60.0
10.5
40.1
30.0
12.0
17.1
. 25.0
4.2
8.7
35.0
2.9
4.0
30.0
1.2
9.2
40.0
3.8
100.0
37.6
Percentage of sphalerite in concentrates : 37.6
Katio of concentration based on original feed : 3.76.
Remarks. The movement of the jig-bed was very similar to Test 42. The bed-
ding-grains were not only carried from the bottom of the bedding-column itself,
but many rose to the top of the ore-column, and a few of the lightest were carried
off with the tailings. The grains of quartz could be seen very plainly rolling
down with the larger bedding-grains and being carried into the hutch.
TEST 45. Sphalerite 10, Quartz 90 per cent.
Stroke: Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Eccentric.
Pulsion and Suction : (135.5 mm.) = 5.33 in. per sec.
On mesh....
Size in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 5.3
B. 85.0
O. 4.6
17.0
80.0
13.6
32.2.
45.0
14.4
18.0
40.0
7.2
9.2
35.0
3.3
4.7
40.0
1.8
13.3
45.0
5.8
99.7
50.7
Percentage of sphalerite in concentrates : 50.7.
Ratio of concentration based on original feed : 5.07.
Remarks. Both the bedding and the ore-column pulsated regularly. Each
formed distinct and well-defined layers. The jig worked very rapidly.
INVESTIGATION ON JIGGING. 37
TEST 46. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev.
Kind
per rain., 160. Length, in. (12.7 m
: Eccentric.
.m.).
Pulsion and Suction (67.7 mm.;
i = 2.66 in. per sec.
On mesh.
...i 12.
20.
40.
60.
80. 100. thro' 100.
Total.
Size in mm.. 1.66
0.97
0.42
0.26
0.21
0.16
0.16
A.
3.4
15.7
29.7
19.0
11.4
5.8
15.0
100.0
B.
100.0
90.0
50.0
35.0
30.0
30.0
40.0
a
3.4
14.4
15.0
6.6
3.3
1.8
6.0
50.5
Percentage of sphalerite in concentrates : 50.5.
Ratio of concentration based on original feed : 5.05.
Remarks. The upper half to three-fourths of the bedding pulsated regularly,
the bottom grains were almost stationary. The lower part of the ore- column con-
sisted of the largest particles of quartz, with smaller and smaller giains to the top.
TEST 47. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev.
Kind
Pulsion : J (135.5 mm.
Suction : f ( 45.2 mm.)
per min., ItiO. Length, in. (12.7 i
: Circular-arc cam.
) = 5.33 in. per sec.
= 1.77 in. per sec.
mm.).
On mesh....| 12.
Size in mm. .| 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
7.0
19.8
34.0
18.8
8.5
3.7
8.0
99.8
B.
60.0
55.0
30.0
25.0
30.
30.0
40.0
a
4.2
11.0
10.2
4.7
2.5
1.2
3.2
37.0
Percentage of sphalerite in concentrates : 37.0.
Ratio of concentration based on original feed : 3.70.
Remarks. The entire bed moved en masse, the top of the column having a
longer amplitude of vibration and requiring a longer time for its completion than
the grains nearer the bottom. The jig worked rapidly.
TEST 48. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., ICO. Length, J in. (12.7 mm.).
Kind : Circular-arc cam.
Pulsion : f ( 45.2 mm.) = 1.77 in. per sec.
Suction : J (135.5 mm.) = 5.33 in. per sec.
On mesh....| 12.
Size in mm.. [ 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
1.1
7.0
35.0
24.6
12.2
5.1
15.0
100.0
B.
90.0
75.0
30.0
25.0
30.0
30.0
35.0
C.
1.0
5.2
10.5
6.2
3.6
1.5
5.2
33.2
Percentage of sphalerite in concentrates : 33.2.
Ratio of concentration based on original feed : 3.32.
Remarks. The bedding pulsated, but not regularly, and tended to thicken in
the middle and thin down at the ends. The grains at the bottom of the ore-
column were in very active agitation, but it was found that these grains were really
describing two distinct orbits.
38 INVESTIGATION ON JIGGING.
TEST 49. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam shaft rev. per min., 160. Length, in. (12.7 ram.).
Kind : Involute cam.
Pulsion : J (101.6 mm.) = 4 in. per sec.
Suction : ( 50.8 mm.) = 2 in. per sec.
On mesh.
Size in mr
...1 12.
a.Jl.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
C.
9.6
50.0
4.8
20.0
65.0
13.0
31.0
35.0
10.8
18.5
25.0
4.2
8.5
30.0
2.5
3.7
30.0
1.1
7.3
40.0
2.8
98.6
39.2
Percentage of sphalerite in concentrates : 39.2.
Ratio of concentration based on original feed : 3.92.
Remarks. The upper two-thirds of the bedding and the entire ore-column
pulsated regularly. As noted before, the grains nearest the top had a longer am-
plitude of vibration and required a longer time to complete it. The lower one-
third of the bedding was quite stationary.
TEST 50. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, f in. (12.7 mm.).
Kind : Involute cam.
Pulsion : ( 50.8 mm.) = 2 in. per sec.
Suction : (101.6 mm.) = 4 in. per sec.
On mesh....
Size in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 0.8
B. 100.0
C. 0.8
8.7
65.0
5.8
41.4
25.0
10.2
22.0
25.0
5.5
10.0
25.0
2.5
4.8
35.0
1.6
11.6
40.0
4.6
99.3
31.0
Percentage of sphalerite in concentrates : 31.0.
Ratio of concentration based on original feed : 3.1.
Remarks. The bedding pulsated slightly, and the grains shifted positions as in
convection-currents. A zone between the bedding and the ore-column moved
much as noted in Test 40. The ore-column above this zone pulsated regularlv,
although the ore-column was not very mobile.
TEST 51. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, J in. (6.35 mm.).
Kind : Circular- arc cam.
Pulsion : \ (67.7 mm.) = 2.66 in. per sec.
Suction : f (22.5 mm.) = 0.88 in. per sec.
On mesh.
Size in mi
.... 12.
n..il.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
1.4
90.0
1.2
9.5
80.0
7.6
44.5
25.0
11.0
22.2
25.0
5.5
9.4
35.0
3.2
4.6
30.0
1.5
8.0
35.0
2.8
99.6
32.8
Percentage of sphalerite in concentrates : 32.8.
Ratio of concentration based on original feed : 3.28.
Remarks. The bedding and with it the ore-column pulsated en masse. Taking
the entire column of bedding and ore as a whole, the top had a much longer am-
plitude of vibration, and required a longer time in which to complete it.
INVESTIGATION ON JIGGING. > 39
TEST 52. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, J in.
Kind : Circular-arc cam.
Pulsion : f (22.5 mm.) = 0.88 in. per sec.
Suction : J (67.7 mm.) = 2.66 in. per sec.
(6.35 mm.).
On mesh ' 12. 20. 40. 60. 80.
Sizeinmm..;1.66 0.97 0.42 0.26 0.21
100. thro' 100.
0.16 0.16
Total.
A. 2.0 11.6 31.8 22.7 11.6
B. 100.0 95.0 45.0 35.0 35.0
C. 2.0 11.0 14.4 8.0 4.2
5.5 14.6
35.0 35.0
1.6 4.9
99.8
46.1
Percentage of sphalerite in concentrates : 46.1.
Ratio of concentration based on original feed : 4.61.
Remarks. Movement of jig-led very similar to that of Test 48, but to
extent.
TEST 53. Sphalerite 10, Quartz 90 per cent.
a less
Stroke : Cam-shaft rev. per min., 160. Length, \ in.
Kind : Involute cam.
Pulsion : (50.8 mm.) = 2 in. per sec.
Suction : (25.4 mm.) = 1 in. per sec.
(6.35 mm.).
On mesh 1 12. 20. 40. 60. 80.
Size in mm..' !.66 0.97 0.42 0.26 0.21
100. thro' 100.
0.16 0.16
Total.
A. 0.6 9.8 30.0 23.8 13.0
B. 100.0 90.0 55.0 40.0 35.0
C. 0.6 9.0 16.5 9 5 4.5
7.5 14.8
30.0 35.0
2.1 5.2
99.5
47.4
Percentage of sphalerite in concentrates : 47.4.
Ratio of concentration based on original feed : 4.74.
Remarks. The bedding pulsated in the upper third and half, and was quite
mobile as well. The lower part, however, was stationary. The line between bed-
ding and ore was horizontal and straight. The ore-column pulsated regularly
the top for a greater distance, and for a longer time, as before.
TEST 54. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev.
Kind
Pulsion : $ (25.4mm.) =
Suction : (50.8mm.) =
per min., 160. Length, } in. (6.35 mm.).
: Involute cam.
= 1 in. per sec.
= 2 in. per sec.
On mesh 12.
Size in mm.. 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100.
0.16
thro' 100.
0.16
Total.
A.
B.
0.8
100.0
0.8
5.4
90.0
4.8
31.2
50.0
15.5
30.0
8.6
35.0
4.5
6.7
30.0
2.1
14.7
35.0
4.9
100.9
41.2
Percentage of sphalerite in concentrates : 41.2.
Ratio of concentration based on original feed : 4.12.
Remarks. The entire bedding was practically stationary, did not pulsate, nor
was it mobile. The interstitial spaces in the upper part of bedding filled with
grains of sphalerite. The ore-column pulsated en masse and was fairly mobile.
40 INVESTIGATION ON JIGGING.
TEST 55. Sphalerite 10, Quartz 90 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, \ in. (6.35 mm.).
Kind : Eccentric.
Pulsion and Suction : } (33.9 mm.) = 1.33 in. per sec.
On mesh I 12. 2O 4o! fio! 8O 100. thro' 100. Total.
Size in mm.. |l. 66 0.97 0.42 0.26 0.21 0.16 0.16
~A. 04 7/7 2972 HM5 ISXJ 8^2 19^5 997e
R. 90.0 95.0 70.0 45.0 40.0 35.0 35.0
C. 0.4 7.3 20.6 9.0 6.0 2.8 6.6 52.7
Percentage of sphalerite in concentrates : 52.7.
Katio of concentration based on original feed : 5.27.
Eemarks. The upper third of the bedding was mobile, but the lower two-thirds
was quite fixed. The ore-column pulsated regularly, together with the upper
third of bedding. The line between the ore-column and the bedding was clearly
marked.
TEST 61. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Circular-arc cam.
Pulsion : } (270.7 mm.) = 10.66 in. per sec.
Suction : f ( 90.2 mm.) = 3.55 in. per sec.
On mesh I 12.
Size in mm..! 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
IOO.thro'100.
0.16 0.16
Total.
A.
B.
C.
6.3
45.0
2.7
28.2
35.0
9.8
33.6
30.0
10.0
12.6
30.0
3.8
6.0
35.0
2.1
2.7
40.0
1.0
9.8
50.0
4.5
99.2
33.9
Percentage of sphalerite in concentrates : 33.9.
Ratio of concentration based on original feed : 1.7.
Remarks. The entire jig-bed pulsated very violently. The feed was very fast,
a large amount of hutch-work was made, and the tailings contained considerable
fine mineral. The fine quartz could be seen sifting through the bedding.
TEST 62. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Circular-arc cam.
Pulsion : f ( 90.2 mm.) = 3.55 in. per sec.
Suction : J (270.7 mm.) = 10.66 in. per sec.
On mesh 12. 20. 40. 60. 80. IOO.thro'100. Total-
Size in mm.. 1.66 0.97 0.42 0.26 0.21 0.16 0.16
A. 1.9 13.2 38.0 18.3 9.7 4.6 14.0 99.7
S. 90.0 75.0 35.0 40.0 40.0 50.0 50.0
C. 1.8 9.7 13.3 7.4 3.8 2.3 7.0 45.3
Percentage of sphalerite in concentrates : 45.2.
Ratio of concentration based on original feed : 2.26.
Remarks. Behavior of jig-bed similar to Test 41.
INVESTIGATION ON JIGGING.
41
TEST 63. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Involute cam.
Pulsion : (203.2 mm.) == 8 in. per sec.
Suction : f (101.6 mm.) = 4 in. per sec.
On
8ia
mesh
j in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 4.8
J?. 70.0
a 3.3
21.5
50.0
10.7
36.8
35.0
12.9
15.1
40.0
6.0
7.8
45.0
3.4
3.3
50.0
1.6
10.2
60.0
6.0
99.5
43.9
Percentage of sphalerite in concentrates : 4H.9.
Eatio of concentration based on original feed : 2.20.
Remarks. Behavior of jig-bed similar to Test 43.
TEST 64. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Involute cam.
Pulsion : (101.6 mm.) = 4 in. per sec.
Suction : ('/03.2 mm.) = 8 in. per sec.
On mesh
Size in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' ICO.
0.16 0.16
Total.
A. 2.3
B. 85.0
a 1.9
17.2
45.0
7.6
37.8
35.0
13.1
17.3
40.0
6.8
8.5
40.0
8.4
4.1
50.0
2.0
12.8
55.0
6.8
100.0
41.6
Percentage of sphalerite in concentrates : 41.6.
Ratio of concentration based on original feed : 2.08.
Remarks Movement of jig-bed similar to Test 44.
TEST 65. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, 1 in. (25.4 mm.).
Kind : Eccentric.
Pulsion and Suction : } (135.5 mm.) = 5.33 in. per sec.
On
Siz<
mesh....
j in mm..
12.
1.66
20.
0.97
40.
0.42
ilO.
0.26
80.
0.21
100.
0.16
thro' 100.
0.16
Total.
A. 2.5
B. 90.0
a 2.2
14.2
80.0
11.2
34.6
50.0
17.2
18.6
40.0
7.4
10.0
4x0
4.5
4.5
50.0
2.2
15.0
60.0
9.0
99.4
53.7
Percentage of sphalerite in concentrates : 53.7.
Ratio of concentration based on original feed : 2.7.
Remarks Movement of jig-bed similar to Test 45.
TEST 66. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Eccentric.
Pulsion and Suction : (67.7 mm.) = 2.66 in. per sec.
On mesh.... I 12. 20. 40. 60. 80. 100. thro'100.
Size in mm.. 1.66 0.97 0.42 0.26 0.21 0.16 0.16
Total.
A. 2.5 12.4
B. 90.0 85.0
C. 2.2 10.5
3^.0
60.0
'20.0
19.0
45.0
8.5
11.0 4.9 17.2
45.0 50.0 50.0
5.0 2.5 8.6
100.0
57.3
42 INVESTIGATION ON JIGGING. ,
Percentage of sphalerite in concentrates : 57.3.
Ratio of concentration based on original feed : 2.8.
Remarks. Movement of jig-bed similar to Test 46.
TEST 67. Sphalerite 20, Quartz 80 per cent.
Stroke: Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Circular-arc cam.
Pulsion : \ (135.5 mm.) = 5.33 in. per sec.
Suction : f ( 45.2 mm.) = 1.77 in. per sec.
On mesh....
Size in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro'
0.16
100.
0.16
Total.
A. 6.1
B. 65.0
a 3.9
.16.3
60.0
9.6
32.4
45.0
14.6
16.9
35.0
6.0
8.7
40.0
3.4
4.0
45.0
1.8
14.2
50.0
7.1
98.6
46.4
Percentage of sphalerite in concentrates : 46.4.
Ratio of concentration based on original feed : 2.32.
Remarks. The bedding and the ore-column pulsated, and the bottom grains
of bedding much more than in Test 66.
TEST 68. Sphalerite 20, Quartz 80 per
cent.
Stroke: Cam-shaft rev. per min., 160. Length, J in. (12.7 mm.).
Kind : Circular-arc cam.
Pulsion: f ( 45.2 mm.) = 1.77 in. per sec.
Suction: (135.5 mm.) = 5.33 in. per sec.
On mesh....! 12.
Size in mm.. 11. 66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
1.2
95.0
1.1
8.1
80.0
6.4
36.4
50.0
18.2
21.6
40.0
8.6
11.2
40.0
4.4
5.6
45.0
2.5
16.5
50.0
8.2
100.6
49.4
Percentage of sphalerite in concentrates: 49.4.
Ratio of concentration based on original feed : 2.47.
Remarks. Movement of jig- bed similar to Test 48.
TEST 69. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (12.7 mm.).
Kind : Involute cam.
Pulsion : J (101.6 mm.) = 4 in. per sec.
Suction : ( 50.8 mm.) = 2 in. per sec.
On mesh....| 12.
Size in mm.. 1 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
C.
5.2
70.0
3.5
18.2
75.0
13.5
32.7
45.0
14.8
17.7
45.0
7.9
9.2
50.0
4.6
4.1
50.0
2.0
12.5
55.0
6.8
99.6
53.1
Percentage of sphalerite in concentrates : 53.1.
Ratio of concentration based on original feed: 2.65.
Remarks. The entire jig-bed moved en masse, and was very mobile. As in all
cases of this kind, the upper part of the ore-column had a longer amplitude of
vibration and required a longer time in which to complete it than the grains
(whether bedding or ore) nearer the bottom.
INVESTIGATION ON JIGGING. 43
TEST 70. Sphalerite 20, Quartz 80 per cent.
Stroke: Cam-shaft rev. per min.,' 160. Length, \ in. (12.7 mm.).
Kind : Involute cam.
Pulsion : % ( 50.8 mm.) = 2 in. per sec.
Suction : (101.6 mm.) = 4 in. per sec.
On mesh....! 12.
Size in mmjl.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A.
B.
a
1.1
95.0
1.0
8.7
80.0
6.8
40.6
45.0
16.2
20.8
35.0
7.4
10.5
40.0
4.2
4.5
50.0
2.2
13.7
60.0
8.1
99.9
45.9
Percentage of sphalerite in concentrates: 45.9.
Katio of concentration based on original feed : 2.29.
Remarks. Movement of jig-bed similar to Test 50.
TEST 71. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, in. (6.35 mm.).
Kind: Circular-arc cam.
Pulsion : \ (67.7 mm.) = 2.66 in. per sec.
Suction : (22.5 mm.) = 0.88 in. per sec.
On mesh....
Size in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 1.1
B. 95.0
c. i.o
12.0
8U.O
9.6
38.5
40.0
14.9
22.0
35.0
7.7
10.0
45.0
4.7
4.6
50.0
2.3
11.2
55.0
6.0
99.4
46.2
Percentage of sphalerite in concentrates : 46. 2.
Ratio of concentration based on original feed : 2.31.
Remarks. Movement of jig-bed similar to Test 51.
TEST 72. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, \ in. (6.35 mm.).
Kind : Circular-arc cam.
Pulsion : f (22.5 mm.) = 0.88 in. per sec.
Suction : J (67.7 mm.) = 2.66 in. per sec.
On mesh....
Size in mm..
12. 20.
1.66 0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 1.8 10.6
B. 10U.O 95.0
C. 1.8 9.9
31.2
70.0
21.7
22.2
50.0
11.1
12.4
45.6
5.6
6.4
50.0
3.8
15.2
60.
9.0
99.8
62.9
Percentage of sphalerite in concentrates : 62.9.
Ratio of concentration based on original feed : 3.14.
Remarks. The entire mass except the lower part of the bedding pulsated en
masse, and the ore-column seemed quite mobile.
44 INVESTIGATION ON JIGGING.
TEST 73. Sphalerite 20, Quartz 80 per cent.
Stroke : Cam-shaft rev. per min., 160. Length, } in. (6.35 mm.).
Kind : Involute cam.
Pulsion : | (50. 8 mm. ) = 2 in. per sec.
Suction : f (25.4 mm.) = 1 in. per sec.
On mesh
Size in mm..
12.
1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100.
0.16
thro' 100.
0.16
Total.
A. 1.3
B. 100.0
C. 1.3
8.7
100.0
8.7
27.2
80.0
21.6
20.6
50.0
10.3
14.1
50.0
7.0
7.1
55.0
3.8
20.8
60.0
12.6
99.8
65.3
Percentage of sphalerite in concentrates : 65. 3.
Katio of concentration based on original feed : 3.26.
Remarks. The upper two-thirds of bedding and the entire ore-column pulsated.
Ore-column mobile.
TEST 74. Sphalerite 20, Quartz 80 per cent.
Stroke: Cam-shaft rev. per min., 160. Length, in. (6.35 mm.).
Kind : Involute cam.
Pulsion : f (25.4 mm.) = 1 in. per sec.
Suction : J (50.8 mm.) = 2 in. per sec.
On mesh 12.
Size in mm.. 1.66
20.
0.97
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
A. 0.9
B. 100.0
a 0.9
6.5
100.0
6.5
24.5
85.0
20.9
20.6
65.0
13.3
15.5
55.0
8.5
7.9
60.0
4.8
24.1
60.0
14.4
100.0
69.3
Percentage of sphalerite in concentrates : 69.3.
Ratio of concentration based on original feed: 3.46.
Remarks. The upper third of bedding together with the ore-bed pulsated en
...jisse. The lower two-thirds of bedding was quite fixed in position. The top of
ore-column, as before, had a longer amplitude.
TEST 7 6. Sphalerite 20, Quartz 80 per cent.
Stroke: Cam-shaft rev. per min., 160. Length, \ in. (6.35 mm.)
Kind : Eccentric.
Pulsion and Suction : \ (33.9 mm.) = 1.33 in. per sec.
On mesh 12. 20.
Size in mm.. 1.66 0.97
A. 0.2 4.2
B. 90.0 90.0
C. 0.2 3.8
40.
0.42
60.
0.26
80.
0.21
100. thro' 100.
0.16 0.16
Total.
29.1
75.0
21.8
20.2
65.0
13.0
13.8
55.0
7.4
7.1
60.0
4.2
24.8
60.0
15.0
99.4
65.4
Percentage of sphalerite in concentrates : 65.4.
Ratio of concentration based on original feed : 3.27.
Remarks. The upper third of bedding together with the ore-column pulsated
en masse. The lower two-thirds of bedding scarcely moved. The interstitkl spaces
of the bedding, as with all experiments with the short stroke, filled with mineral.
INVESTIGATION ON JIGGING.
45
5. Discussion of Results.
It is evident that in a machine so simple as the jig there are
a number of variables, and a series of tests may therefore be
Eccentric
Involute
Circular Arc,
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
MEAN DIAMETER OF GRAINS, MM. MEAN DIAMETER OF GRAINS, MM.
FIG. 6. CHART OF RESULTS OF GROUPS 1 AND 2 OF CLASS I.
classified according to some one of them. For purposes of dis-
cussion, however, the tests that have been conducted are grouped
r
^-
-
-9
Eccentric
Involute
Circular Arc
IN CONCENT
I g s t
X"
/*
<X
^
^
r \
'X
x
X*"
5
X- 1
-^"
-i 05
t
/
x
/
^
X"*
'
""""
3"
-20
15
L
/
/
**>
*-*
7_
X
X*'
II
//
/
/"
I/'
/
Group 3
Galena 10 Per cent.
Quartz 90 Per cent.
/
*/
Group 4
Galena 10 Per cent.
Quartz 90 Per cent.
PERCEf
>
/,'
'/
//
/'"'
/"'
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.0 1.8
MEAN DIAMETER OF GRAINS, MM. MEAN DIAMETER OF GRAINS, MM.
PJG. 7. CHART OF RESULTS OF GROUPS 3 AND 4 OF CLASS I.
according to the velocity of the rising current of water, or pul-
sion-currents, as measured by the mean piston-speed. Figs. 6
46
INVESTIGATION ON JIGGING.
F
Iccentric
nvolute
ircular Arc
_-l
C
_
31
-31
29
/
.
-ri
/
/*
26
/
/=
~S
/
.
>-"
L
_...
22
2
/ X
^__.
.=--.-
-32
"80
r^
2---
:.---
30
-24
'///
/*
---33
/
@
/
/
,x.
^
""^
Hfl
/
/
fit
*
It
2
//'/
1 I/
-;
I
a
$
/J
I
1
Group 1
Galena 20 Per cent.
Quartz 80 Per cent.
Qm
Group 2
ena 20 Per cent,
rtz 80 Per cent.
!
''
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.2 0.4 0.6 0.8 .1.0 1.2 1.4 1.6 1.8
MEAN DIAMETER OF GRAINS, MM. MEAN DIAMETER OF GRAINS, MM.
FIG. 8. CHART OF RESULTS OF GROUPS 1 AND 2 OF CLASS II.
^**
B8
"25
Eccentric
Involute
. Circular Arc
^^
--
^-27
^
/
,38
t*~
--*
^-23
^
s^
^
^-'
--J1
/
***
/
?
fe
/,-
' '/
</
' /
//
1
/
1,
1
//
//
ij
I
/
_ //
/I/
/
L
Group 8
Galena 20 Per cent.
Quartz 80 Per cent.
7
/
Group 4
Galena 20 Per cent.
Quartz 80 Per cent.
I
/
|
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
MEAN DIAMETER OF GRAINS, MM. MEAN DIAMETER OF GRAINS, MM.
FIG. 9. CHAKT OK RESULTS OF GROUPS 3 AND 4 OF CLASS II.
INVESTIGATION ON JIGGING.
47
to 13, inclusive, show graphically the results given in row C,
under each of the experiments, calculated for the mean diame-
Eccentric
Involute
Circular Arc
Group 1
- Sphalerite 10 Per cent.
Quartz 90 Per cent.
Group 2
Sphalerite 10 Per cent.
Quartz 90 Per cent.
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.2 QA 0.6 0.8 1.0 1.2 1.4 1.6 1.8
MEAN DIAMETER OF GRAINS, MM. MEAN DIAMETER OF GRAINS, MM.
FIG. 10. CHART OF RESULTS OF GROUPS 1 AXD 2 OF CLASS III.
PERCENTAGE OF SPHALERITE IN CONCENTRATE
^oSKggggg&gg
1
^4.'>
TT
ccentric
ivolute
ircular Arc
^
-^
c
/
/S
/
-ZZ-
%
/
'"X
,/>-
***'-'
/
'''/
;
,--"
*m ii '"*
"^^
/
^
S
?
XT"
.- '
'
/
/
V
/',
^
//
Group 3
Sphalerite 10 Per cent.
Quartz 90 Per cent.
^
Group 4
Sphalerite 10 Per cent.
Quartz 90 Per cent.
X
/
/
/^
1
/-'^
C.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
MEAN DIAMETER OF GRAINS, MM. MEAN DIAMETER OF GRAINS, MM.
FIG. 11. CHART OF RESULTS OF GRODPS 3 AND 4 OP CLASS III.
ter of the material. Since all material treated on the jig passed
through a screen having a square hole, the mean length of the
48
INVESTIGATION ON JIGGING.
PERCENTAGE OF SPHALERITE IN CONCENTRATE
c*sssisgg&ft8:8S3
i
j
ccentric
nvolute
Circular Arc
,.-
.-
To
c
-_73
\
^
,'
7i
X
' x ""
,;
/''
is'-'
.-'
X
X
^
_
-66
69
7
x
:
^.
*^-
70
/
x
,'
/
.-
-===-
71
-=r=r-~-
,=70
a ,-
-'"
,---'
''
I
/
x^
x -
34
,\ffY,
/
' I
^
/ x
**'
JUT
/I/4'-
M.
Cl
m
I
y
j I//
/ft!
j
1
}'/J V .J
Group 1
lalerite 20 Per cent,
irtz 80 Per cent
/
/ J
H
Group 2
Sphalerite 20 Per cent.
Quartz 80 Per cent.
'' 1 p
T \ Q"
r
_J
r
1
0.2 0.4 O.G 0.8 1.0 1.2 1.4 1.6 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
MEAN DIAMETER OF GRAINS, MM. MEAN DIAMETER OF GRAINS, MM.
FIG. 12. CHART OF RESULTS or GROUPS I AND 2 OK CLASS IV.
/-
___ '
-^
-M
I^r
centric
volute
pcular Arc
Xx
'
--07
01
X
x
'
s~
^
- 04
. -
-C,3
//
X
:>
''
/
^
I
/ --x
~
X
^ *
p*^*
-01
///
.
f
X
I
/
/
/
"^
III
y
/
1
Group 3
Sphalerite 20 Per cent.
Quartz 80 Per cent.
/ / -
Group 4
Sphalerite 20 Per cent.
Quartz 80 Per cent.
F
>
?
'
1
1
/
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
MEAN DIAMETER OF GRAINS, 'MM. MEAN DIAMETER OF GRAINS, MM.
FIG. 13. CHART OF RESULTS OF GROUPS 3 AND 4 OF CLASS IV.
sides of which was equal to 2.136 mm., and from that as a
maximum to the very finest dust, it has been assumed that the
INVESTIGATION ON JIGGING. 49
mean diameter of the grain caught on the 1.66-mm. screen is
(2.136 -f 1.66) -T- 2 = 1.90 mm. ; those passing the 1.66-mm.
screen and caught on the 0.97-mm. screen, have a mean diame-
ter of (1.66 -|- 0.97) -T- 2 = 1.31 mm., and so on for all the
sizes; and, finally, that the material passing the 0.16-mm. screen
(the finest used in these tests) had a mean diameter of 0.08 mm.
In the curves shown in Figs. 6 to 13 the diameter of the grain has
been plotted along the X axis, and the weight of pure mineral
(galena or sphalerite) on each screen-size, as given in the record
of the tests, laid off on the Faxis. The points thus located have
been joined by three classes of lines : the solid lines in all cases
represent the results obtained in the tests made with the eccen-
tric cam ; the dotted lines, tests with the involute cam ; and,
finally, the broken lines, tests with the circular-arc cams.
The velocities of the pulsion- or rising-currents, as measured
above, have been divided, on purely arbitrary grounds, into four
groups : (1) velocities of pulsion 2 in. (50.8 mm.) per sec. and
less ; (2) velocities of pulsion from 2 to 4 in. (50.8 to 101.6 mm.)
per sec. ; (3) velocities of pulsiou from 4 to 6 in. (101.6 to
152.4 mm.) per sec.; (4) velocities of pulsion from 6 to 10.66 in.
(152.4 to 271 mm.) per sec. With this arrangement it has so
happened that in nearly every case the tests with the involute
cam are plotted in two groups. The experiments with the eccen-
tric and circular-arc cams occur once only in each group. Since
each pair of minerals has been run with 10 and with 20 per cent,
of either galena or blende, two classes are to be distinguished.
In all cases under discussion, Classes I. and III. will refer to
mixtures containing 10 per cent., and Classes II. and IV. to mix-
tures with 20 per cent, of the heavy mineral.
In order to facilitate reference, the following classification is
given :
CLASS I. Galena and Quartz. Galena 10, Quartz 90 per cent.
Group 1. Velocities of pulsion from to 2 in. (0 to
50.8 mm.) per sec.
Tests 8, 11, 12, 14, 15, 17, 18.
Group 2. Velocities of pulsion from 2 to 4 in. (50.8 to
101.6 mm.) per sec.
Tests 2, 4, 6, 9, 10, 12, 16.
50 INVESTIGATION ON JIGGING.
Group 3. Velocities of pulsion from 4 to 6 in. (101.6 to
152.4 mm.) per sec.
Tests 4, 5, 7, 9.
Group 4. Velocities of pulsion from 6 to 10.66 in. (152.4
to 271 mm.) per sec.
Tests 1, 3.
CLASS II. Galena and Quartz. Galena 20, Quartz 80 per
cent.
Group 1. Velocities of pulsion from to 2 in. (0 to
50.8 mm.) per sec.
Tests 28, 30, 31, 32, 34, 35, 37.
Group 2. Velocities of pulsion from 2 to 4 in. (50.8 to
101.6 mm.) per sec.
Tests 22, 24, 26, 29, 30, 31, 33.
Group 3. Velocities of pulsion from 4 to 6 in. (101.6 to
152.4 mm.) per sec.
Tests 24, 25, 27, 29, 38.
Group 4. Velocities of pulsion from 6 to 10.66 in. (152.4
to 271 mm.) per sec.
Teste 21, 23.
CLASS III. Sphalerite and Quartz. Sphalerite 10, Quartz 90
per cent.
Group 1. Velocities of pulsion from to 2 in. (0 to
50.8 mm.) per sec.
Tests 48, 50, 52, 53, 54, 55.
Group 2. Velocities of pulsion from 2 to 4 in. (50.8 to
101.6 mm.) per sec.
Tests 42, 44, 46, 49, 50, 51, 53.
Group 3. Velocities of pulsion from 4 to 6 in. (101.6 to
152.4 mm.) per sec.
Tests 44, 45, 47, 49.
Group 4. Velocities of pulsion from 6 to 10.66 in. (152.4
to 271 mm.) per sec.
Tests 41, 43.
CLASS IV. Sphalerite and Quartz. Sphalerite 20, Quartz 80
per cent.
Group 1. Velocities of pulsion from to 2 in. (0 to
50.8 mm.) per sec.
Tests 68, 70, 72, 73, 74, 75.
INVESTIGATION ON JIGGING. 51
Group 2. Velocities of pulsion from 2 to 4 in. (50.8 to
101.6 mm.) per sec.
Tests 62, 64, 66, 69, 70, 71, 73.
Group 3. Velocities of pulsion from 4 to 6 in. (101.6 to
152.4 mm.) per sec.
Tests 64, 65, 67, 69.
Group 4. Velocities of pulsion from 6 to 10.66 in. (152.4
to 271 mm.) per sec.
Tests 61, 63.
Class L, Group 1. Galena, 10 per cent. The two lowest ratios
of concentration were obtained with two tests with eccentric
cam, using a short stroke and a high frequency in Tests 17 and
18; and of these two, Test 18, with only a -j^-in. stroke and
400 strokes per min., yields the lowest ratio of the series. An
examination of the screen-analysis shows a marked difference
between Tests 18 and 15 ; the longer and slower stroke has
caused a larger percentage of the finest size to pass into the
hutch ; but the shorter and more rapid stroke has increased
the percentage of material between 1.31 and 0.69 mm. in the
concentrate. In this case, at least, piston-speed does not deter-
mine whether the jig-bed will be pulsated, or the proportions of
coarse and fine material carried into the hutch.
The highest ratio of concentration is clearly with the involute
cam, Test 11, with a pulsion -velocity of 2 in. (50.8 mm.) and
suction-velocity of 1 in. (25.4 mm.) per sec. A good catch of
fine material is made, and the three largest sizes are of good
proportions as to weight and mineral-content the sudden drop
in value for particles of 0.34 mm. diameter should be noted.
Tests 8, 12, 14, and 15 represent the three types of strokes.
The weak pulsion and strong suction of Tests 8 and 14 have
produced results very similar to those of the eccentric. This
style of cam, therefore, between the limits of this group, is not
more efficient than the eccentric. In none of the experiments
of this group has any material of mean diameter 1.90 mm.
been carried through the sieve and into the hutch. It cannot
be said that strong suction is superior to moderate suction in
saving the fines.
Class L, Group 2. The minimum ratio of concentration is
that with the involute cam, Test 4 representing the highest
52 INVESTIGATION ON JIGGING.
limit of velocity of pulsion for this group and very strong suc-
tion. The strong suction, however, has not resulted in increas-
ing the proportion of fines, probably owing to the fact that there
is also a rather high puleion- velocity.. The conditions in this
test have been favorable for the recovery of grains of mean
diameter of 0.69 mm. (on 0.42-mm. screen). The highest ratio
of concentration is obtained in Test 6, an eccentric, with velocity
of pulsion and suction 2.66 in. (67.7 mm.) per sec. Test 10, an
involute cam, with slow pulsion and rapid suction, gives results
similar to Test 6. Test 9 gives very good results, with high
pulsion and slow suction, just the reverse of Test 10. In this
latter case the strong pulsion is clearly an advantage, resulting
in almost as good a saving of fines, and a much larger and
cleaner product on the large sizes. Test 4, with circular-arc
cam, and Test 16, with eccentric cam, give results quite close.
Why Test 4 should differ so materially from Test 2 is not easy
to explain. Tests 10 and 4 represent the velocity-limits of the
group and show marked differences in results ; and in Tests 4
and 9, with the same velocity of pulsion, but different suction-
velocity, the strong suction has produced a much smaller per-
centage of the finest size and contains less galena, although the
strong suction has been very effective in drawing material having
a mean diameter of 0.69 mm. into the hutch. The eccentric,
with short stroke and high frequency, Test 16, gives a low ratio
of concentration. In all cases only a small catch is made with
sizes larger than about 1 mm., and at least from 75 to 95 per
cent, of the mineral saved in the hutch is of a diameter of
0.69 mm. or less.
In this group the same pulsion-velocity but variable suction-
velocity give different results ; the high suction-velocity is not
of any distinct advantage in increasing the catch of fines or
in enriching any of the sizes. The eccentric at proper rotative
and pulsion-speeds yields results equal and in most cases supe-
rior to an accelerated and retarded stroke.
Class I., Group 3. In this group of four experiments, Test
4, which was also placed with group 2 of this class, and occu-
pied the lowest position, is also the lowest in this group. The
highest ratio of concentration is found in Test 9, an involute
cam with the same pulsion-velocity as Test 4, but only one-
fourth the suction-velocity. As noted under group 2, the
INVESTIGATION ON JIGGING. 53
strong suction has resulted in producing a smaller amount of
the finest size, and in a decreased percentage of galena in all
the sizes. The intermediate positions are marked by an eccen-
tric cam, Test 5, and a circular-arc cam, Test 7, and with the
same velocity of pulsion.. The strong pulsion and weak suction
has resulted in a larger saving of the fine material than in the
case of the eccentric, and a somewhat higher ratio of concen-
tration.
It appears, therefore, that in this group the involute cam
with strong pulsion and weak suction is the most efficient in
producing a high concentrate, and the reverse of these condi-
tions the least efficient; that the circular-arc cam, Test 7, with
strong pulsion and weak suction, is somewhat more efficient
than the eccentric; and that the same velocities of pulsion
yield different results.
It will be noted, also, that all the tests in this group produced
some of the coarsest size, and those of strong pulsion and weak
suction the largest amount. In comparing this group with
group 2 of this series, we find that the maximum ratio has been
passed, and that velocities of pulsion more than 4 in. (101.6
mm.) per sec., with the size of material jigged, should not be
exceeded.
Class I., Group 4. Only two experiments occur in this group,
Tests 1 and 3. Length of stroke in each case 1 in. It appears
that the circular-arc cam with the highest velocity of pulsion
and least velocity of suction gives a little higher ratio of con-
centration, but that the results are very much the same. The
proper limit for pulsion-velocities has long since been exceeded.
Comparing Tests 3 and 4 in the same way, it is found that
strong pulsion and weak suction produced practically the same
percentages of sieve-sizes, but with strong suction the per-
centage of heavy material is much reduced. Even with these
high velocities of pulsion, a strong suction is not an advantage,
in increasing either the amount of fine material drawn into the
hutch or the percentage of heavy mineral.
Class II., Group 1. Galena, 20 per cent. Of the seven tests
in the group, the involute cam, Test 31, with velocity of pul-
sion at the maximum limit of the group, gives the highest ratio
of concentration. The same was true under Class I. The final
minimum ratio is indicated by the reciprocal of Test 31, with
54 INVESTIGATION ON JIGGING.
weak pulsion and strong suction. "With material up to 0.69
mm. in diameter, the eccentric with short and rapid stroke
gives the lowest ratio in Test 37, while at the same piston-
speed at twice the length of stroke and half the number of rev.
per min., the values are very close to the maximum in Test 35.
The involute cam in Test 30, with weak pulsion and strong
suction, produces similar results but at different velocities, but
at the same ratio to Test 32. In this case the strongest suction
has drawn a larger percentage of the fine stuff into the hutch,
but has not enriched it.
The two circular-arc cams, Tests 28 and 34, with weak pul-
sion and strong suction, give similar results, in which about 30
per cent, of the hutch-product passes through a 100-mesh (0.16
mm.) sieve. But again, in Test 31, with the involute cam,
strong pulsion and weak suction, a larger percentage of tine
material is drawn into the hutch. The eccentric gives about
the same percentage of fines as in Test 31.
It may be said for this group that the eccentric at the proper
length and rotative velocity gives excellent results, and is
generally superior to an accelerated or retarded stroke. The
same pulsion-velocities give different results.
Class II., Group 2. The minimum ratio of concentration is
indicated by the circular-arc cam, Test 33, with strong pulsion
and weak suction. The maximum is attained with an involute
cam, Test 81, with rapid pulsion and weak suction. The in-
volute cam has already been considered under the first group.
Test 29, also an involute, under the same conditions, gives good
ratios, but the higher pulsion-velocity results in a smaller sav-
ing of the very fine material; larger sizes appear more abund-
antly in the hutch, however. Tests 24 and 30, involute cams
with suction in excess of pulsion, give final results that are very
close, but the strongest suction, Test 24, yields relatively less
fine and more coarse material than the weaker suction.
It will be noted, further, that with the exception of Test 31,
some stuff larger than 1.66 mm. is found in all the products.
The circular-arc cam with very high velocity of suction has pro-
duced a relatively high percentage of the finest size. The
eccentric, Test 26, gives good average results a large per-
centage by weight of the finest, and containing at least an
average percentage of galena. With the exception of Tests 29
INVESTIGATION ON JIGGING. 55
and 31, the five other tests are, in general, much the same.
Both of these tests have been classed in other groups. Of the
three highest ratios of concentration, two have low suction-
velocity and the third has equal pulsion and suction.
Class II., Group 3. Of these five tests the minimum is found
in Test 24, repeating the conditions of Test 4. It will be
noted, however, that until the size next the largest is reached,
the lowest ratio is indicated by the eccentric, Test 38, with short
stroke and high rotative speed. Test 29, involute cam, strong
pulsion and weak suction, and Test 25, eccentric, at the same
piston-speed as Test 38, give almost the same final results.
The circular-arc cam, Test 27, strong pulsion and weak suc-
tion, produces results very similar to those of Tests 25 and 29.
In all cases with these high pulsion-velocities, more material
having a diameter of 1.31 and 1.90 mm., and correspondingly
less of the finer sizes, have been obtained. The advantages of
high suction-velocity over those of pulsion are not apparent.
Class II., Group 4. An examination of the two tests in this
group indicates at once a close correspondence. The maximum
limit for pulsion-velocity has been passed, but it appears that
with the richer feed these velocities vary between considerably
wider limits than with the poorer material.
In general, it may be said for all the tests, that for each
condition under which jigging takes place, certain sizes 20- or
40-mesh (0.97 or 0.42 mm.) are very rich, and then on smaller
sizes a very violent drop in the percentage of galena takes place.
This will be noticed for all tests on galena and blende as well.
Also, that moderate suction and stronger pulsion give better re-
sults than the reverse. The strong pulsion usually results in a
larger yield of the coarser sizes of higher percentage in mineral,
and the fines are saved almost equally as well. In most cases
the eccentric, at the proper length of stroke and rotative speed,
is equal and usually superior to accelerated or retarded stroke ;
but when the stroke becomes too short and the rotative speed
high, the ratio falls off. Observations on the behavior of the
bed under these conditions showed that the bedding and ore-
column pulsated, although at the same piston-speed with the
longer stroke no movement in the bedding took place. This
indicates that, with very sudden impulses to the ore-column, the
water acts more like a solid than a liquid, and that mineral-
56 INVESTIGATION ON JIGGING.
particles are not subject* to the full force of a rising current of
water, but that the material is sifted down through the inter-
stitial spaces of the bedding. Possibly another cause is at work,
as noted in the behavior of the bed during the long strokes.
Here the top of the bed pulsated for a longer time, and had a
longer amplitude of vibration, and therefore the grains on the
bottom came to rest sooner than those above, which would tend
to limit the size of the particles passing into the hutch; and
the longer and slower the stroke above the limits which will
move the grains, the more pronounced will this differential
motion be, and with it the increased perfection of the classifi-
cation that must take place.
Class III., Group 1. Sphalerite, 10 per cent. Here the lowest
ratio is found in Test 50, with weak pulsion and strong suc-
tion. An examination of the weights and percentages of
Tables IV. and V. shows, however, that only relatively small
amounts of the finest sizes are secured ; but material ot
0.69 mm. (on 40-rnesh) is recovered to an amount equal to
about 41 per cent., while material larger or smaller than this
size is not materially increased. Test 48, under similar con-
ditions, gives similar results. Both of these tests indicate that
strong suction, within the limits of this group, is not advanta-
geous. Test 54, with the same ratio of pulsion and suction, but
only one-half the intensity, gives a higher ratio ot concentra-
tion and a slightly better recovery in the finest sizes. Test 52,
under analogous conditions, gives somewhat, similar results,
except material on 20-mesh (1.31 mm. mean diameter). Test
53, involute cam, with strong pulsion and weak suction, gives
very good results. Test 55, eccentric, gives the best results of
all. In this case, not only a high percentage of the finest sizes
of fair mineral-content was obtained, but the coarse sizes also
were well represented, containing a high percentage ot sphal-
erite, which accounts chiefly for the high ratio of concentration.
It may be said for this group that the eccentric easily yields
the best results ; that strong suction and weak pulsion give the
lowest, and weak suction and strong pulsion an improved ratio
of concentration.
Class III., Group 2. An inspection of the tests in this group
shows that the lowest ratio of concentration is indicated by
Test 50, an involute cam, with strong suction and weak pul-
INVESTIGATION ON JIGGING. 57
sion, already considered in Class IIL, Group 1 ; and very near
it is Test 51, a circular-arc cam, with strong pulsion and weak
suction, resulting in the production of very small amounts oi
the finest sizes ; but nearly 45 per cent, of material on the 40-
mesh (0.69 mm. mean diameter). Tests 42, 44, and 49 give
results in the final ratios that are close together, but differing
in the details. Test 42, circular-arc cam, with moderate pulsion
and strong suction, and Test 49, involute cam, with strong pul-
sion and weak suction, give practically the same final result;
and Test 44, involute cam, with moderate pulsion and strong
suction, similar results.
The two higher ratios are those of Test 46, eccentric, and Test
53, involute cam, with strong pulsion, but the lowest for the
group, and less suction. An inspection of the records of the
experiments shows that, with the relatively low pulsion-velocity
used, these two tests yielded relatively less of the coarsest sizes,
but increased amounts of the finest sizes.
The superiority of the eccentric over the other forms of stroke
is at once evident. In the case of all styles of stroke, the same
pulsion-velocity gives final results much the same.
Class III., Group 3. Of the four tests grouped here, three
are almost identical namely, Tests 44, 47, and 49 ; and of
these three, two have already been considered in Class III.,
Group 2. Test 47, circular-arc cam, with strong pulsion and
weak suction, and Test 49, also strong pulsion and weak suc-
tion, produce about the same results as very strong suction and
weaker pulsion, but in which, however, the pulsion-velocity is
about the same. This indicates that the velocity of pulsion is
the principal determining factor.
Class IIL, Group 4. The two tests in this group are very
closely related. It is evident that the proper velocity of pul-
sion has been passed. The records of the experiments show
that, at these high velocities, the coarse sizes readily pass into
the hutch, but at the same time the percentage of mineral is
much decreased, and much of the fine material is lost.
An examination of the four groups indicates that in the
fourth the maximum velocity of pulsion has been exceeded
for good work, but in the other three groups the best velocity
is not so clearly indicated. With the three eccentrics good
ratios have been secured in each of the groups, and this is
58 INVESTIGATION ON JIGGING.
also the most efficient of the three types of stroke. A high
pulsion-velocity is very efficient in saving material that rests on
20- and 12-mesh (1.31 and 1.90 mm. mean diameter of grain),
but on sizes smaller than these less so than decreased velocities.
A high suction- velocity is not generally more efficient in re-
covering the finest sizes than a more moderate one.
Class IV., Group 1. Sphalerite, 20 per cent. A comparison
with the corresponding group of Class II. shows many features
in common. The lowest ratio of concentration is found in
Test 70, and next to it Test 68, both weak pulsion and strong
suction. Test 72, the reciprocal of Test 68, gives better results.
Tests 73 and 74, reciprocals of each other, indicate that be-
tween these velocities the involute cam is very efficient. Test
74, with strong suction, gives the highest ratio of the group.
Class IV., Group 2. Some differences as compared with the
corresponding group of Class I. are found here. The minimum
ratio of concentration is marked by Test 64, involute cam, with
moderate pulsion and strong suction. Tests 62, 70 and 71
62 and 70, circular-arc cams and involute, respectively, with
weak pulsion and strong suction, and Test 71, with strong
pulsion and weak suction give results that do not differ
materially, indicating once more that even though the suction-
velocity differs widely, the final results will not differ widely
if the pulsion-velocities are close together. The eccentric,
Test 66, shows a good ratio. Test 73, an involute cam, with
stronger pulsion than suction, gives the maximum ratio for the
group.
Class IV., Group 3. The four tests in this group give re-
sults agreeing very closely with the corresponding group of
Class I., and the observations made under that group apply
here.
Class IV., Group 4. A glance shows at once that this group
agrees exactly with the corresponding group under Class I.
An examination of the four groups of Class II. indicates
that in the tirst, with a pulsion-velocity not exceeding 2 in.
(50.8 mm.) per sec., the highest ratios are obtained, and that
at these velocities by far the largest percentage of the mineral
recovered has a mean diameter of 0.69 mm. (through 20-mesh.).
As the velocity is increased, more of the coarse sizes appear
and less fine material.
INVESTIGATION ON JIGGING. 59
For both Classes III. and IV., with sphalerite and quartz, it
appears that generally a stronger pulsion-velocity than suction
is more efficient in producing a better concentrate, and effects
an equally good saving of the fines. The eccentric, between
wide velocity-limits, is an efficient type of stroke. Of the two
types of cams, the involute is generally the best. An examina-
tion of the tests will show that certain types and velocities of
strokes are especially suited to the recovery of particles of fixed
diameters.
Y. DISCUSSION OF PULSION AND SUCTION.
Since the pulsion- and suction-velocity, as measured by the
piston-speed, have been the chief variables in this investiga-
tion, the question naturally arises : can the exact role of each
be definitely defined ?
The accepted meaning of the terms "pulsion" and "suction"
is doubtless familiar to all. A pulsion-current is one acting
opposite to gravity, and tending to raise the grain off the jig-
sieve; and a suction-current is one acting in the direction of
gravity and supplementing it. In both cases, therefore, are
reactions caused by the movement of a column of water or
other liquid relative to some solid.
When the results of a series of tests are arranged according
to the pulsion-velocity in the free part of the jig-column, or, in
other words, the piston-speed, even though the suction-velocity
differed widely, the final results are quite close together, in-
dicating that the reactions occurring during this cycle deter-
mine the final result. With a perfect-fitting piston, given the
areas of piston and jig-sieve, length and number of strokes per
unit of time, the mean pulsion-velocity in the free or unoccu-
pied section of the jig-column may be accurately determined ;
and similarly for the suction-velocity.
It has been demonstrated that under the reaction of pulsion
with mixed sizes of grains of different specific gravities cer-
tain definite positions are established according to diameters.
Thus, in the case of quartz and galena, the grain of quartz in
equilibrium with a particle of galena was 5.8 times the diam-
eter of the galena grain.
Stated in other words, the results of the pulsion-jig experi-
ments indicate that in order to effect a perfect separation by
60 INVESTIGATION ON JIGGING.
pulsion alone, the grains should be sized between the limits of
these ratios, which may be distinguished from those of " free-
settling ratios" by "interstitial equilibrium factors," or " hin-
dered-settling ratios or factors." It is important to note that
they are larger than those obtained by Rlttinger's well-known
formula. This formula states that in the case of a sphere the
uniform velocity under " free-falling " conditions is :
'v = 5.11 i/d(z 1.0)
in which,
v = Velocity of fall in meters per second.
d = Diameter of sphere in meters.
x = Specific gravity of sphere.
1 = Specific gravity of liquid (unity in case of water).
Thus, in the case of quartz and galena, if for x the specific
gravities of the two minerals are substituted, equating and solv-
ing for the respective diameters, a ratio of about 4 to 1 is ob-
tained. It is evident that the reactions occurring during pulsion
have resulted in increasing materially the ratios possible under
" free-settling " conditions. It seems to me that part of this
increase may be accounted for according to Professor Munroe's 10
grain of maximum falling-velocity. He has shown that in a tube
the grain of maximum falling-velocity is one having a diameter
0.4 that of the tube. Under the force of pulsion the interstitial
channels are constantly undergoing a change in their diameters.
A small grain of heavy mineral surrounded by the larger grains
of lighter mineral will have frequent opportunities for occupy-
ing a channel about 2.5 times its own diameter. No doubt the
greater acceleration of the small particle over that of the large
one will always aid the separation, as pointed out by Rittinger.
It is evident that the experimental interstitial-factors or ratios
obtained in the pulsion-jig are much smaller than called for
by Munroe's theory, 11 where, in the case of above minerals, large
grains closely surrounded by smaller ones, he obtains a ratio of
about 31 to 1 for equal-falling grains.
Whatever may be the theoretical diameter-ratios between
two minerals under pulsion, it is an easy matter, as pointed out
by Professor Richards, 12 to determine what it is under practical
conditions, and the ratios that exist under these conditions on
a jig-bed are the ones that most closely concern the mill-man.
10 Trans., xvii., 645 (1888-9). u Trans., xvii., 650 (1888-9).
12 Trans., xxiv., 484 (1894).
INVESTIGATION ON JIGGING. 61
As a resultant of all the forces acting upon the grains during
the pulsion-cycle, a certain definite and distinct separation takes
place according to the diameter-ratios of the two minerals.
When this point has been reached, further separation, or an
increase in the diameter-ratios, is not possible. In order now
to remove the small grain of heavy mineral from the large
grains of light mineral associated with it, the application of some
other reaction is necessary. This force is suction, or, perhaps
more properly, the reactions that occur during the suction-cycle.
Under the conditions that exist in a jig-bed, we are dealing
with a number of columns of water moving with some velocity
relative to the grain. The forces acting upon the grain will
be those of the water-currents, of gravity, and of the resist-
ance opposed by the walls of the channel or other grains.
The effect of the water-current alone upon the grains may be
considered a purely non-selective force. For grains of the same
size and shape a given current will exert as much effort upon a
particle of galena as upon one of quartz. Any advantage that the
small heavy grain has over its larger companion, due to accelera-
tion, will always be a positive force. The resistance offered to
the passage of the grain by other surrounding grains will de-
pend upon the relative diameter of the channel and the grain,
and the length, shape, and inclination of the channel. If the
grains are all the same size and shape, then the mean diame-
ter of the channels will be less than the diameter of any of the
grains, and none of them could be carried through the intersti-
tial spaces. Take as an extreme case a column of shot, steel
balls, or marbles of the same diameter, they are all absolutely
fixed as regards any possible suction-velocity. The same is
true, through to a less extent, in rounded particles not all the
same size, as well-worn sand, gravel, etc. Again, the possi-
bility of the mass becoming packed is small. Of course, the
reason for this is well understood, and is owing to the fact that
in these cases the surfaces of the particles are curved, and
therefore the points in contact are reduced to a minimum.
Under any practical conditions existing in the jig-bed, the par-
ticles are not all the same shape or size, and instead of being
bounded by curved surfaces they are angular and bounded by
planes. This results in neighboring grains having not few but
many points in contact, accompanied always by a more or less
62 INVESTIGATION ON JIGGING.
wedging action, and therefore jigging under excessive suction-
velocity results in a tight bed. The wider the size-ratio the
greater the effect, and vice versa. The possibility of applying
suction depends upon the ability to maintain within the jig-bed
interstitial channels somewhat larger than the maximum grain
to be saved. Under the conditions existing on a jig-bed, the
effect of increasing the diameter-ratio of bedding and feed, the
number of bedding-grains in a vertical column, or thickness of
bed, and the character of the bedding-grains themselves, whether
they are rough and angular, cubical, or well worn and spherical,
is at once evident.
The increased catch secured on a jig-bed over that obtain-
able by rising current alone, under either free or hindered set-
tling conditions, is due to the reaction occurring during suc-
tion. In order that suction may become effective, it is necessary
that the reaction of pulsion precede. During pulsion a selection
and arrangement takes place ; and during suction a destruction
of the conditions of equilibrium set up under pulsion, by the
removal of the small heavy grain through the interstitial chan-
nels into the hutch, results. Suction always supplements gravity,
but in a way in which gravity cannot act efficiently that is,
in the movement of grains in channels more or less inclined
or crooked, where a particle could easily lodge, although large
enough for the grain to move in if vertical. The current moving
with high velocity in these spaces serves to move the particle.
Pulsion may be said to be the master reaction, while suction is
its necessary complement, completing what has been initiated
by pulsion. Suction is therefore necessary in jigging all unsized
material. Excessive suction with sized material, under prac-
tical conditions, would be disadvantageous. With very close
sizing on coarse jigs it would not be particularly harmful, but
it would be useless. In jigging under any conditions, more or
less suction will be of advantage, as helping to save the smaller
particles of heavy mineral that otherwise might be carried ofi
with the tailings.
VI. DISCUSSION OF ACCELERATION.
It has been pointed out (Tests 16, 17, 18, 37) that with a
very short and quick stroke, but relatively low piston-speed,
the ratio of concentration obtained was low. Moreover, the
INVESTIGATION ON JIGGING. 63
jig-bed pulsated under the influence of the short, rapid stroke,
and did not with the longer one of less frequency, but having
the same mean piston-speed in inches or millimeters per sec.
This was a movement of the grains en masse, the bottom pul-
sating quite as much as the top, and was altogether different
from that gentle, selective action observed with proper speeds
and frequencies. The jig-bed moved as it would if acted on
by a solid piston from below. Thus, by giving many quick
sharp blows to the jig-bed, the water-columns have not time to
adjust themselves to the increased pressures, except by raising
the grain which happens to be in the direction of impulse. In
addition to the mean piston-speeds, as derived from Professor
Munroe's formula, 13 the element of time during which the im-
pulse lasts should be included. This solid or piston-effect of a
water-column can, perhaps, never be entirely eliminated, nor
does it seem desirable that it should be. The results show
that increased quantities of hutch-work are produced, supple-
menting suction by keeping the interstitial channels cleared.
Since the grains on the bottom are the first to feel the impulse
and be raised, it has been shown that true pulsion is dimin-
ished, and the important reactions dependent on it dimin-
ished. Sharp, rapid strokes, by increasing the piston-effect,
promote sifting, and therefore aid suction, but decrease the re-
action of pulsion.
VII. RESUME AND CONCLUSIONS.
Referring to the 13 conclusions of Professor Munroe, quoted
in the early part of this paper, it may be said that no experiments
have been carried out with the idea of duplicating the work cov-
ered by the first six of his conclusions. In the absence of posi-
tive experimental data, it may be considered quite out of place
to enter into a discussion of them. However, in the light of
results of the present investigation, a few observations concern-
ing these first six conclusions may be given. The careful record
of so many tests, under the conditions observed by Professor
Munroe, seems to cover the field thoroughly.
Conclusions 1, 2, and 3 are undoubtedly fundamental propo-
sitions in any system of jigging. To Professor Munroe is due
the credit of having first clearly pointed these out and applying
1S Trans., xvii., 647, 648 (1888-9).
64 INVESTIGATION ON JIGGING.
them to jigging. Following, as corollaries, are the formulas
given for the velocity of fall of grains en masse. The formulas
for the falling- velocities of grains en masse under the assumed
conditions, when applied to piston-speed, have been demon-
strated by experiments with the pulsiou-jig, the Yezin jig, and
the Harz jig yield satisfactory results.
Conclusion 4 has been noted elsewhere. A grain 0.4 the
diameter of the channel will have a maximum falling- velocity,
which therefore increases its chance of being saved, and of
increasing the interstitial settling-ratio.
Conclusion 5, in the first part, follows, also, from the first
three conclusions, and its application fully demonstrated by Pro-
fessor Munroe. It seems to me that there is a reasonable doubt
about accepting the second part of this conclusion. There is
no doubt about this part of it : " The falling-velocity .
[of a mass of grains] increases or diminishes with the distance
apart of the grains," since this is merely a re-statement of Con-
clusions 1, 2, 3, and 5. When, however, the balance of this
statement is examined that is, " . . . the velocity of the
current necessary to support or raise the mass of grains increases
or diminishes with the distance apart of the grains," I believe
we are entitled to withhold judgment until it has been shown
what these velocities, under the conditions of jigging, actually
are. This statement is true if we assume that the velocities
supporting or raising the grain are equal to the observed veloci-
ties in the free or unobstructed part of the tube ; or in practice
the piston-speed. But are these the velocities acting upon the
grains ? Under the conditions obtaining on a jig-bed, the
grains occupy a considerable area, and therefore constrict the
passage. It is a matter of actual observation that the velocity
in the interstitial spaces is much higher than that of the jig-
piston. It is the same principle of conducting a given volume
of water through a pipe-line made up of, say, a 12-in. and a 6-in.
pipe. In the 12-in. pipe the column of water will have a mean
velocity of x feet per sec., and in the 6-in. section the velocity
has been increased to 4 x. Thus, we must be careful not to
confuse the falling-velocity of grains en, masse with the velocity
of the water-column actually supporting them during pulsion.
It has been noted by Professor Munroe that spheres falling
in tubes have a maximum falling-velocity when the diameter
INVESTIGATION ON JIGGING. 65
of the sphere is 0.4 that of the tube ; and spheres either smal-
ler or larger than this size fall with less velocity. If the col-
umn of water in the tube has a velocity of 0, or is at rest, a
solid falling through this water-column will displace a vol-
ume of water equal to its own volume as often as it trav-
erses a distance equal to one of its three dimensions. This
displaced volume must escape within the interstitial space of
tube and body with some velocity, depending on the velocity of
the falling body and the ratio of the diameters of the falling
body and the tube. If the falling body has a diameter nearly
equal to that of the tube, the area of the interstitial space is
small, and a low falling-velocity of the body may correspond to
a high interstitial velocity of the water-current. Thus, while
the velocity of fall decreases as the diameter of the solid
approaches that of the tube, at the same time the velocity of
the current tending to support it increases. If the body has a
diameter equal to that of the tube, any motion of the solid
would mean an infinite velocity to the interstitial current, and
the body stops. On the other hand, as the diameter-ratio
between the solid and the tube increases, the area of the inter-
stitial space increases, and the volume of displaced water de-
creases, and with it the interstitial velocity, and the body would
tend to fall with a high velocity ; but the force causing it to
fall, its weight, is also smaller, and therefore its ability to over-
come the inertia of the liquid, and other resistances, is less, so
that its falling-velocity is less. The possibility of interstitial
currents depends upon a solid of any diameter less than the
tube, and having a specific gravity greater than that of the
liquid, and which is free to fall, or resists the motion of a
column of the liquid in which it is immersed.
It is evident that if a velocity be given to the water-column
in the free part of the tube equal to the observed velocity of fall
of the body in the stationary column, then the body will be sup-
ported or remain at rest. This velocity of the water in the
column is the apparent velocity necessary to support the grain,
and some function of the actual velocities supporting it. In
jigging, it is not so much the velocity of fall of a mass of grains
that concerns us, as the velocity of the current necessary to
raise or support them. In jigging, the grains are not free to
fall, since they are firmly supported on a sieve, but they are
66 INVESTIGATION ON JIGGING.
quite free to move when the interstitial currents are acting
in pulsion. When the force due to the velocity of the rising
currents is greater than all other forces holding the body
at rest, then the body moves in the direction of the greatest
forces, and continues its motion so long as the forces are unbal-
anced. Thus, it has been observed that the particles will be
raised to positions higher than at rest during the action of the
pulsion-current. The grains in the bed are being raised because
each one in motion is seeking a position higher up in the column
where the distance between grains is greater, or, in other words,
where the interstitial velocity is lower.
Conclusion 6 admits of no doubt.
Conclusion 7 is an axiom as regards the first part. The
second part concerns the ratio of equal-falling particles of
the pair chosen namely, quartz and galena. No ratios were
obtained in any of the investigations approaching those called
for by this theory. Evidently the conditions required by the
theory were not present. The conditions assumed were that
the fine grains should closely surround the large grain of
quartz. It has been observed in all experiments that the large
grains quickly settled on the bottom the smaller and lighter
above, whether of bedding or ore. This fact was also pointed
out by Professor Munroe in his paper on his experiments
with mixed shot. 14 There is but one force that can carry the
small, light grain to the top. That force resides in the velocity
of the interstitial currents acting during pulsion. Certainly, in
the pulsion-jig experiments, where the unsized material was
thoroughly mixed, and added practically dry in order to avoid
any classification in falling through a water-column, and where
very large percentages of the heavy mineral (over 70 per
cent.) were used, the above ratios should have been secured.
In the case of the above pair it was found that a particle of
galena and one of quartz 5.8 times its diameter were in equi-
librium. If the conditions called for by the theory were present,
and the results not fulfilled, then an examination of the theory
is in order. But we have observed above that while the
material was thoroughly mixed when added to the tube, the
fine, light grains immediately separated from the large, heavy
14 Trans., xvii., 649 (1888-9).
INVESTIGATION ON JIGGING. 67
ones during the first few strokes of pulsion. From this we
must conclude that the fine, light grains were not in equi-
librium with the large neighbors, and sought positions higher
up in the column where they were. When this was found
they remained fixed, or were in equilibrium. These ratios
have been given elsewhere. For quartz and galena the ratio
was 5.8 to 1.
The conditions assumed cannot, under any possible condi-
tions, exist on the jig-bed, and therefore the results that would
follow cannot possibly be attained in practice. The conditions
would be fulfilled if we caged all the light and heavy grains,
and prevented any movement among them ; but this is the
very condition that we do not want on a jig-bed. It is hardly
fair to assume that if in one way or other we are able to keep
a mass of mixed grains together, under conditions where the
small fellows cannot escape, therefore the small grain is fall-
ing with the same velocity as the large grain. It is in equi-
librium by force, not choice; and on the jig-bed we try, as far
as possible, to encourage the grains to exercise the latter and
not the former.
Possibly if formulas had been derived showing the velocity
of the interstitial currents (the currents supporting or raising
the grain), and from these, equal-settling ratios were derived,
the values would be much less than 31 to 1, and probably close
to those obtained in the pulsion-jig.
Conclusion 8 follows from the conclusions 1, 2, 3 and the
first part of 5. I can bear testimony as to the practical accu-
racy of this, since I have calculated many a piston-speed
and velocity in the free tube in the pulsion-jig. With the
formulas given, it has been shown that with pulsion-jigs,
Vezin jigs, Harz jigs, etc., the piston-velocity so calculated
suffices to move the grains. Given the size or diameter, and
the specific gravity of the minerals to be separated, the jig-
piston velocity may be calculated with almost a nicety. It has
been shown in the experiments in piston-velocity that a consid-
erable variation is permissible in jigging.
Conclusion 9, the first part of Conclusion 11 and all of 13
are corollaries of the last part of Conclusion 7. Since the con-
ditions assumed for Conclusion 7 cannot exist on a jig-bed,
therefore no support is left for 11 and 13, and some other ex-
68 INVESTIGATION ON JIGGING.
planation must be given to account for the applicability of the
English system. This action has been discussed under pulsion
and suction.
Conclusion 10 has been abundantly demonstrated. It
might be added that if the theory were applicable little or no
suction would be necessary.
Conclusion 11. The last part of this conclusion, concerning
the presence of more or less coarse material in jigging very
fine material, agrees with practice, since, if not in the feed, a
bed is used, which fulfills the conditions. The tests do not
cover cases in which any large percentage of feed was less than
0.10 millimeter.
Conclusion 12 accords with all results of practice and experi-
ment, and is therefore another fundamental proposition in
jigging.
Finally, to Professor Munroe must be given the credit for
having pointed out the fact that bodies fall with less velocity
in tubes than in large bodies of w r ater, and for having dem-
onstrated the applicability of formulas based on this fact to ob-
tain correct jig-piston velocities under the assumed conditions.
It is to be always understood throughout this paper, that
under records of the experiments, where pulsion-velocity and
suction-velocity are given, the value expressed in inches or milli-
meters per second is that of the piston or the water-column
in the free or unobstructed part of the jig only, and clearly not
the actual pulsion-velocity acting upon the grains during these
reactions. One is a function of the other, but under the very
conditions obtaining on a jig they cannot be equal.
Comparing the results given by Professor Richards, a part
of whose conclusions are quoted earlier in this paper, it will be
found that, so far as the experiments may be compared, there is
a very close agreement between us. Since we both started from
the same experimental basis, on which we were agreed, it is but
natural that our conclusions should be in close harmony. This
theorem, which forms the basis in every practice of jigging, is
all important, and of course is the establishment of the value
of the resultant measured by the diameter of grains differing
in specific gravity obtained during pulsion alone. This factor
represents all that can possibly be expected from every force
acting upon the grains of a jig-bed during the time the pulsion-
INVESTIGATION ON JIGGING. 69
currents are acting, or while the grains are free to fall. To
Professor Richards is due the credit of having demonstrated the
value of this resultant as measured by the ratios of diameters.
My own researches, carried out in a different manner (see pul-
sion-experiments), have abundantly confirmed the substantial
accuracy of these ratios. When, therefore, Professor Richards
says: "The two chief reactions of jigging are pulsion and
suction," I see no escape from them. If we go a little further
and say : " The reactions occurring during pulsion and suction
are the only reactions of jigging," we have included every force
imaginable that can act upon the grains. As pointed out above,
the resultant of all the forces acting upon the grains during
pulsion is given by the interstitial or hindered-settling ratios as
determined by Richards and myself. The resultant of suction
cannot be separately determined, apart from that of pulsion.
There is no determinable resultant of suction as measured by
a ratio or factor.
Summarizing some of the principal points brought out in this
investigation, I believe the following may safely be accepted :
(1) The pulsion-reaction is by far the most important one in
the process of jigging. During this period, with sized grains
of different specific gravities, with proper pulsion-velocity, the
separation between them will be complete. The size-limit is
indicated by the hindered-settling ratio. If the minerals are
not sized, or above these ratios, the separation cannot be com-
plete, but a definite arrangement will result. The positions of
equilibrium will be attained when the above ratios of diameters
are attained, after which further separation by pulsion is im-
possible.
(2) Suction due to the movement of water-columns supple-
ments gravity. Resisting the sum of these two forces is the re-
sistance of the walls of the tube through which the grain must
pass. The reaction, as a whole, must therefore be a resultant.
The chief components are the force of the water-columns, which
are purely non-selective, but act with equal intensity upon all
particles of the same shape and size, regardless of their specific
gravity or weight. Any advantage that the small heavy grain
would have over a large light one would, of course, appear in
the resultant tending to carry it to the hutch. The effect of
the forces opposing the movement of the grain depends upon
70 INVESTIGATION ON JIGGING.
the character of the grain, and the conduit through which it is
supposed to pass. Under any condition, the diameter of the
grain cannot be greater than that of the conduit. If the chan-
nels are inclined, or crooked and zigzag (the condition obtain-
ing on a jig-bed), the particles will more easily lodge against
the sides of a tube large enough to pass through if the tube were
vertical, but under the force ot gravity they remain at rest.
The rapidly descending water-currents passing through these
channels easily carry the grains along. Thus suction, due only to
the moving columns of water, constitutes a powerful impelling
force to carry through the interstitial spaces those particles which
under the force of gravity alone cannot move. Suction is, there-
fore, a necessary complement to pulsion in the jigging of all
unsized material, and generally valuable in jigging under all
conditions.
(3) From the observations under (2) it is clear what effect
the bedding will have upon the result. Any part of the bed-
ding or ore-column remaining fixed during the pulsion-cycle
must be looked upon merely as a mass of very irregular tubes,
of length somewhat greater than the thickness of such part,
owing to their inclination, since they are mostly inclined. To
that extent they are only an extension of the jig-sieve. The
result of thickening or thinning the bed, or of increasing or
decreasing the size-ratio between bedding and feed, is evident.
This assumes, of course, that the largest particle or feed is
smaller than the sieve-aperture, and always the bedding-grain
must be larger than the sieve-aperture. It is evident, too, that
the shape of the bedding-grain will have a marked effect.
Grains that are more or less equi-dimensional, as galena, etc.,
will form a more open bed than one of antimony, which breaks
into long pencil-shaped grains. Finally, of course, if the bed-
ding is in use long enough all grains become worn and spher-
oidal. Any part of the bedding free to pulsate is to be con-
sidered as part of the ore-column, and is amenable to all the
conditions applying to this reaction.
(4) The effect of very rapid acceleration, amounting to a
shock or blow to the bottom of the jig-bed, is an important
factor. Its effect is to accelerate the work done by suction,
and render a larger catch possible with a low mean piston-
velocity. The pulsation of the jig-bed due to this force and
INVESTIGATION ON JIGGING. 71
that taking place under the regular interstitial velocity should
be distinguished. One sifts, the other separates.
(5) The results of the many experiments, in which the piston-
speeds during the pulsion and suction were not the same, seemed
to show that only by properly balancing the two are the best
results attained. It has been generally noted that the eccentric,
giving equal mean velocities, yields about as good results as any
of the accelerated strokes. This observation applies only for
the size-ratio used in the tests, and it is not safe to speculate
what the results would be for other sizes.
(6) While the use of the jig for the treatment of material
sized between wide limits is possible and practicable, still the
advantages that are bound to follow where a more or less perfect
sizing has preceded cannot be denied. It must be observed,
that in the English system itself, when the hutch-prodncts of one
jig are treated on another we are using sizing.
(7) The more general application of the English system, or
the use of the jig in the treatment of unsized material instead
of the hydraulic classifier, seems to be clearly indicated. This
has been recognized in some quarters, but a wider use than has
hitherto been accorded it appears to hold out favorable induce-
ments. This seems to be a field eminently suited for the
English methods of jigging one that is not and cannot be filled
by the Continental system.
(8) The arguments that have been advanced for the adoption
of the English system on the ground that equal-settling ratios,
many times larger than those obtainable under free-settling con-
ditions, exist on the jig-bed, are not tenuble. These hypotheti-
cal ratios cannot possibly exist on a jig-bed.
In conclusion, I must acknowledge the great help and many
suggestions derived from the works of Professor Richards and
Professor Munroe; to the latter personally, I owe cordial thanks
for numerous timely suggestions. I have also had the benefit
of his valuable criticism in the construction of the laboratory-
iig, with which many of the experiments were made.
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