UNIVERSITY OF CALIFORN WOOD RESIDUE USES IN THE CALIFORNIA PINE REGION William A. Dost HQVoO'QS i i V* *m CALIFORNIA AGRICULTURAL EXPERIMENT STATJON BULLETIN 817 The forest products industry throughout the West, and particularly in California, is undergoing rapid changes in technology, processes, and structure. One reason for these changes is the increased application of technology in all industries, but other reasons are undoubtedly more important — prime timber is becoming less available and competition with other materials for markets is more intense. New products and processes have enabled alert and aggressive firms to bargain for timber supplies on an advantageous basis since they are in a position to utilize a greater portion of the log brought in from the woods. As time passes, both size and quality of the available timber will decrease and a greater and greater part of the log will be lost to residues. Use of these residues will become increasingly necessary. This bulletin evaluates alternate uses for residues. It deals with raw material requirements, capital requirements, processing and other pertinent data. It does not intend to give a processor all the information he needs in order to decide on a given process, but it should help him eliminate some processes as unsuited to his particular operation. He can then study the more promising alternatives in more detail. Unique uses for wood residues were not a goal in the study. The available literature was reviewed to find the major uses for wood residues that have been successful in the past. As a result of this review the following ap- plications are evaluated in this bulletin: Particleboard 3 Wood chips 7 Wood flour 8 Wood particle molding 11 Molding pulp products 13 Horticultural bark 15 Sawdust soil conditioners 16 Charcoal 17 Miscellaneous products 20 A method of residue determination was evaluated on residues from two sawmills and one remanufacturing plant in the California Pine Region; the method and results are presented in the Appendix, page 21. THE AUTHOR: William A. Dost is Extension Forest Products Specialist, Agricultural Extension, Berkeley. ACKNOWLEDGMENT The author is indebted to the Cal-Ida Lumber Company for its support of this study and for making available data necessary to it; and to Robert Kundrot for assistance in the field study and the survey of literature. F. E. Dickinson and H. C. Sampert were particularly helpful with their suggestions. OCTOBER, 1965 WOOD RESIDUE USES IN THE CALIFORNIA PINE REGION 1 PARTICLEBOARD The particleboard industry continues to grow rapidly. Yet it is plagued by excess capacity and declining prices. Technology is still developing fast and the higher-quality boards are accepted most readily in the market. The minimum economical plant in the West requires 50 tons of raw material per day; the optimum, 100 tons or more. However, past experience shows that any plant at less than optimum at the time of construction will have difficulty remaining com- petitive for an extended period. The most desirable raw material, generally speaking, is green wood of lumber trim and edging size or larger. Planer shavings may also be acceptable. The manufacture of particleboard is often the first possibility considered by a manufacturer faced with the necessity of utilizing his wood residues. The market for this material has grown tremendously since the first plant was installed in Ger- many in 1941 and the United States in 1945. From this beginning, production in 1957 reached 183 MM sq ft on a % " basis and for 1963 was 494 MM sq ft. There are a number of specific processes available. These are described in some detail on pages 27-34 of Graham and Parrish ( 1961 ) . a Recent installations have heavily favored the production of a high- quality board — a multiplaten product, usually a three-layered board. Its main advantages over extruded boards are its better dimensional stability and the better surface that can be obtained. Also, multi- platen board strength is relatively uniform in all directions parallel to the surface of the board while extruded board shows distinct differences. The extrusion process requires a lower capital investment and can operate at lower production rates, but the product's characteristics limit its market acceptance. Consequently, most of the extrusion board installations are "captive" operations in which production and use conditions can be well coordinated. Production of ex- truded board declined by about 10 per cent in the period 1957 to 1961. Properties and uses The uses for particleboard are expanding with advancing product technology. A recent study showed that 80 per cent of the particleboard produced was used by the furniture trade and as core material for the manufacture of hardwood veneer and plywood. Since that study, construction uses have increased and, in 1963, more than one-fourth of all U. S. production was used as floor underlayment. In es- sence, particleboard is used as an alternate to lumber or plywood. Here, briefly, are the properties required of a competitive board : • Hardness — at least equal to the ma- terial it might replace. • Density — comparable to solid wood, at most no more than 25-35 per cent higher. The most desired boards are in the range of 40-42 lbs/cu ft. • Stiffness — sufficient to prevent warp- age of veneered panels. • Bending strength — must be adequate for the intended use. • Creep resistance — equal to lumber under reasonable loads. • Tensile strength perpendicular to board surface — should be adequate. • Dimensional stability — better than lumber of equal dimensions. • Flatness — no tendencies to warpage. • Smoothness — should not "telegraph" through crossbands and veneers. 1 Submitted for publication September 4, 1964. 2 References refer to the selected bibliography at the conclusion of each section. [3] • Gluability — bonds to veneer must be strong enough so that failure occurs within the particleboard. However, low-strength veneers should rupture internally before the particleboard or the glue line. Must permit edge-glu- ing, banding and veneering by the same methods used with lumber and plywood. • Finishing — should accept all types of paints, stains, shellacs, varnishes, and waxes. • Machining — should be easy to ma- chine and permit use of carbon steel tools. • Fastening — should permit use of screws in both edge and face, as well as the use of nails. Manufacture The particleboard production process is described in some detail in Graham and Parrish (1961). Briefly, it includes reduc- ing the wood to the desired size, drying, mixing with adhesive and other additives, forming into a mat, and pressing. Newer plants usually incorporate a refinement in the mat formation step which results in a board with fine particles on the sur- face. Investment Capital investment requirements depend both on the process selected and the oper- ating capacity. The extrusion process should only be considered for a "captive" plant. The optimum size for a multiplaten process is from 20 MM to 40 MM sq ft of 3 A " board/year. In the West in 1962, four plants operated with a capacity of less than 10 MM sq ft/year, three between 10 MM and 20MM and eleven from 20 MM to 60 MM sq ft/year. The trend is clearly toward larger operating units. 100 tons/ day is equivalent to 20 MM sq ft/250-day year of 40 pcf 3 A " board. The table below presents capital costs, either estimated or reported, for particle- board installations of different sizes for several years. A prominent particleboard plant engineering and construction firm indicates that, in 1963, in very general terms a reasonably efficient plant did not cost more than $20,000 per ton of daily output. In recent years, minimum economical size has been suggested as ranging between 35 and 50 tons output per day or roughly 10 MM sq ft per year. However, western plants are generally larger than this, the trend appears to be to still larger plants, and a high mortality rate exists in the in- dustry. Consequently, a plant should be planned not simply for profitability under current operating conditions but also should anticipate future changes. For ex- ample, a recently constructed plant has a 60 MM sq ft capacity. Raw Material Requirements Minimum raw material requirements are about 50 tons per day. In the West, an installation of less than 100 tons output/ day should be considered unusual under present conditions. Particleboards are made from a spec- trum of wood residues ranging from dry sawdust to green solid wood. In general, dry wood residues do not make as high quality a product as do green residues; Estimated Capital Costs Size 1955 1956 1959 1960 1961 1962 MM sq ft Thousand dollars 5 7 507 705 550 650 800 900 3,000 850 1,600 2,000 8 10 12 15 20 25 6 000* * Total capitalization. [4] 3 o T / 100- / — x Production 4 nn _,___ Number of plants ■1 / / / so / / / 40 - / » P / — < / A / 30 \ 1,^^ k / X ?0 J i 10 t 1/ > X \ / ( a c a > l— — ' .^.j ^J ^ 19! 6 19! »8 19 60 19 62 19 64 Fig. 1. United States particleboard production. and edgings and trims or larger pieces are preferred to fine pieces. Marketing The rate of expansion in the industry has been explosive and there seems to be no sign of a leveling off. But other factors, too, enter the marketing picture. Figure 1 shows the relation between production capacity and actual production. Much of the unused capacity is no doubt in captive plants or is obsolescent. However, its existence combined with the turnover in operating firms indicates that the tech- nology is still developing fairly rapidly and that competitive pressures are high. Recent price trends (figure 2) show a decline but a substantial portion of this may be ascribed to improved manufac- turing techniques resulting in lower pro- duction costs. The price picture empha- sizes the necessity of designing new plants for adaptability while holding production costs as low as possible. Freight rates represent a substantial fraction of the total price to the customer, $46/M sq ft 3 A " bd delivered to the East Coast. Therefore, the location of a plant with respect to its competitors and its markets is of utmost importance. Each manufacturer of particleboard for the competitive market seems to provide [5] 1 1 1 _ Max 1 1 1 1 *»nd u£ tons/hr 2-3 tons/hr Equipment $75,000 46,500 72.500 19,500 $62,000 $ $123,000 81,000 $167,000 Conveyors, hoppers, bins, etc Buildings Contingencies 138,000 Total $213,500 $62,000 $275,000 $204,000 $305 000 References Anonymous 1957. Charcoal production in the United States. Washington, D. C. Serv. Div. of For. Econ. Res. 14 pp. USDA For. 19] 1961. Charcoal production, marketing, and use. Madison, Wise, U. S. For. Prod. Lab. Rept. 2213. 1961. Charcoal briquettes sales. Raleigh, N. C, Aeroglide Corp. Inf. Bui. 402. 1962. Charcoal. FAO of the UN, Rome, Occasional Paper 2. 1963. Charcoal and charcoal briquette production in the United States, 1961. Wash- ington, D. C, USDA For. Serv. Div. of For. Econ. and Marktg. Res. 33 pp. Beglinger, E. 1952. Charcoal production. Madison, Wise, U. S. For. Prod. Lab. FPL No. R1666- 11. Hempf , F. E. 1957. Production and sale of charcoal in the Northeast. Upper Darby, Pa., North- eastern For. Exp. Sta. Paper 100. Jarvis, J. R. 1960. The wood charcoal industry in the state of Missouri. Columbia, Mo., Univ. of Missouri Eng. Ser. Bui. 48. Kasile, J. 1962. Wood charcoal production in California for 1961. Berkeley, Calif., Pac. South- west For. and Range Exp. Sta. Res. Note 210. Keppler, W. E., and W. T. Huxter 1962. Feasibility guide for charcoal briquetting plant. Raleigh, N.C., Wood Prod. Ext. Sect., Sch. of For., North Carolina State College. Pritchard, W. M. 1960. A simplified charcoal retort. For. Prod. Jour. 10(12) : 640-41. 1961. Simplified batch retort permits economical charcoal production. Hitchcock's Wood Working Digest 63(3) : 48-50. Simmons, F. D. 1957. Guides to manufacturing and marketing charcoal in the northeastern states. Upper Darby, Pa., Northeastern For. Exp. Sta. Paper 95. Warner, John R., and W. B. Lord 1957. The market for domestic charcoal in Wisconsin. St. Paul, Minn., Lake States For. Exp. Sta. Paper 46. MISCELLANEOUS PRODUCTS Sweeping compounds are feasible, current needs are probably The manufacture of sweeping compounds supplied from local sources in each market Wood shavings from sawdust presents a limited oppor- area, tunity for sawdust utilization. Ingredients usually are sawdust, paraffin oil, powdered wax, salt, sand, and fragrance and coloring A g° od market for wood shavings exists, materials as desired. Proportions vary but largely as poultry and livestock litter. Pine one formula uses 30 parts sawdust, 1 part and tru e fir species are preferred in this paraffin oil, 1 part salt, 10 parts sand, and us e, and incense cedar is unacceptable, a small amount of powdered wax. Shavings are normally baled, but occasion- The oil and wax are generally heated all Y ma Y be sold in bul k- and the dry ingredients added to it. Mixing . is done in a tumbling drum similar to a Bne l"etted wood concretemixer. Compressed wood fines fuel logs have No study of markets was made. Pre- been produced for many years and an sumably marketing would be through established market exists. Each machine janitorial supply houses or jobbers. Since for the production of the only important investment is limited and small operations product of this type requires approxi- [20] mately 12 tons of kiln-dried residues per day. Mill sales price of this product in Humboldt County in the fall of 1963 was $14 per ton. Markets are largely in metro- politan areas, and distance to markets is important. Merchandising is a factor that is not very well exploited by most current producers. A potential market, just beginning to be exploited, is for recreational use. This mar- ket could perhaps be best served by smaller production units located in the market area. A process which seems to have several advantages for this approach has recently been developed by the British Columbia Research Council. Their "Fuel Log Process" uses wet sawdust as a raw material to produce a log which does not disintegrate on outside storage. The log making machine sells for about $5,000 including royalties and can pro- duce about 1,300 pounds of logs in eight hours. This should facilitate pilot or small plant operations although the most effici- References ent operation would include a battery of machines. Production costs have been estimated at $20 per ton. This means that in order for the operation to compete with other processes, a special market situation must exist. It must be possible to minimize both transportation and sales costs. Areas with both summer and winter recreation and adjacent to the producer, such as near Lake Tahoe and Mt. Shasta, might meet these requirements to a high degree. It has also been reported that a wafer- ing machine developed for processing cattle fodder is suitable for use on wood fines. Cubes or briquettes produced by this method might also be saleable to the recreational market and compete directly with charcoal, but actual saleability and production problems and costs have not been evaluated by the author. Use of these products as a heat source for the protection of crops has been tested in a limited way with encouraging results but the use has not been developed. Anonymous 1962. Sawdust floor-sweeping compounds. Madison, Wise, U. S. For. Prod. Lab. FPL No. 1666-14. 3 pp. 1964. Fuel log process. Vancouver, B. C, British Columbia Res. Council. 6 pp. Ivory, E. P. 1956. Reducing sawmill waste 90 per cent in six years. For. Prod. Jour. 6(8) : 279-81. Reineke, L. H. 1955. Briquets from wood waste. Madison, Wise, U. S. For. Prod. Lab. FPL No. 1666-13. 7 pp. APPENDIX: RESIDUE ESTIMATION A firm contemplating the use of its proc- essing residues must first determine and classify these residues by type and volume. This can be done in a number of ways. Estimates may be made from averages re- ported by industry or from studies in vary- ing detail made at a particular operation. The outline of a very intensive study of residues developed at a particular opera- tion, based on a materials balance, is re- ported by Shelton (1954). At the other extreme is the sampling of the material in the burner conveyor for a short period of time, then scaling up this sample to esti- mate total production. The materials bal- ance approach requires more manpower than may be available to most operators. On the other hand, sampling and the use of industry averages may provide insuffi- cient or erroneous answers. Several refer- ences on residue surveys are listed on page 26. The procedure described here lies be- tween these extremes. It is well within the capability of any firm, and yet it provides accurate information in detail adequate for sound planning of most ventures. This study was made of a firm in the California Pine Region operating two sawmills and a remanufacturing plant. [21] Table A-l. Log Size Frequency Distribution for the Three-month Sample Period Bd ft class Diam. class (inches) Number of logs Bd ft class midpoint Diam. class (inches) Number of logs midpoint Mill A Mill B Mill A Mill B 25 8 9 5 30 4 9 725 31 32 35 32 37 36 75 10 11 12 13 56 72 90 98 14 18 22 25 775 33 29 34 825 34 26 33 875 35 23 31 950 36 20 30 125 14 15 103 103 29 32 1050 37 38 18 16 28 26 175 16 17 99 95 35 38 1150 39 15 24 1250 40 13 22 225 18 19 91 86 41 43 1350 41 42 12 10 20 15 275 20 21 81 77 45 47 1450 43 44 9 7 13 10 325 22 72 47 1550 45 46 6 5 8 375 23 67 46 6 425 24 62 45 1650 47 4 5 475 25 58 44 1750 48 3 5 525 26 27 54 50 43 42 1850 49 50 3 2 4 3 575 28 46 40 1950 51 1 2 625 29 43 39 2050 52 1 1 675 30 39 38 Procedure Sawmills — Chippable material available was estimated at each sawmill. A sample of logs was measured and followed through the headrig. Breakdown pattern for each log was recorded and slab volume determined, assuming a round cross-sec- tion but taking taper into account. The volume of individual edging pieces was estimated and an average value applied to each board edged from the sample logs. Trimming data were developed from saw spacings and from a sampling of grade trimming practices. Trim residues were assumed to be constant for all log diame- ters since trimming for grade in the con- ventional sense did not appear to be prac- ticed. Bark volume was estimated from bark thickness and log diameter and length data. Sawdust volume was not esti- mated but this could be done from the available data. Remanufacturing plant — Total chippa- ble residues were computed on the basis of past pulpwood shipments plus an esti- mated 5 per cent additional now being shunted to the burner and the boiler. A rough estimate only was made of fine resi- dues at the remanufacturing plant because fine residues are less promising than coarse residues for the manufacture of useful products. The estimate was made on the basis of computed current consumption for steam production. [22 Sawmill Residues Generated on a Daily Cut of 75 MBM Log Scale Item Mill A Chippable wood Bark Mill B Chippable wood Bark Cu ft/MBM Cu ft/day Cu ft/240-day year 36.9 21.4 31.1 20.0 2767.5 1605.0 2332.5 1500.0 664,200 385,200 559,800 360,000 * Sawdust not included. Results The amount of chippable residues avail- able at the sawmills depends on the spe- cies, size, and quality of the logs being cut. Log data were available for only a three- month period of 1963; they are presented in table A-l, giving log size frequency dis- tribution. Figure 5 shows the relationship between log diameter and chippable ma- terial produced per MBM log scale. The similar relationship for bark, which did not vary noticeably between mills, is given in figure 6. Table A-2 presents the effect of differences in log diameter distri- butions, showing chippable and bark residual per MBM as affected by log Table A-2. Cubic Feet of Residual per MBM as Affected by Log Diameter Bdft class Diam. class (inches) Chippable wood Bark, both mills Bdft class midpoint Diam. class (inches) Chippable wood Bark, both midpoint Mill A Mill B Mill A Mill B mills 25 8 9 33.0 30.2 725 31 32 23.0 22.2 28.7 27.8 17.1 17.1 75 10 11 12 13 78.5 71.0 27.7 25.6 23.6 20.8 775 33 21.5 26.9 17.1 825 34 21.0 26.1 17.1 875 35 20.6 25.4 17.1 950 36 20.1 24.7 17.1 125 14 15 64.3 58.5 74.2 20.3 19.0 1050 37 38 19.7 19.4 24.0 23.5 17.1 17.1 175 16 17 53.8 49.3 66.8 61.0 17.7 16.6 1150 39 19.1 22.8 17.1 1250 40 18.8 22.3 17.1 225 18 19 46.0 42.2 55.6 51.4 15.8 15.2 1350 41 42 18.6 18.3 21.7 21.3 17.1 17.1 275 20 21 39.2 36.6 47.6 44.5 15.0 14.9 1450 43 44 18.2 18.1 20.8 20 4 17.1 17.1 325 22 34.3 41.7 15.0 1550 45 46 18.0 17.9 20.0 19.5 17.1 375 23 32.2 39.6 15.3 17.1 425 24 30.5 37.9 15.7 1650 47 17.8 19.3 17.1 475 25 28.8 36.2 16.2 1750 48 17.7 19.0 17.1 525 26 27 27.5 26.7 34.7 33.2 16.5 16.8 1850 49 50 17.6 17.5 18.7 18.4 17.1 17.1 575 28 25.5 31.9 17.0 1950 51 17.4 18 17.1 625 29 24.6 30.8 17.0 2050 52 17.3 17.7 17.1 675 30 23.7 29.6 17.1 [23] 90 l\ \ i CO * 60 \ \ r 3 50 \\ 72 w 0> _Q 40 O Q. Q. JC U 30 \ > Mill B Mill A 10 Diameter (inches) Fig. 5. Cubic feet of chippable wood residual per MBM log scale from logs of various diameters. diameter. If a significant shift in diameters of logs were to occur, the amount of residues anticipated to be available should be adjusted according to the table. A daily cut of 75 MBM/day would pro- duce the volumes of residues shown in the table "Cubic Feet of Residual per MBM as Affected by Log Diameter" on page 23. 45 30 15 1 2 3 4 5 G Diameter (inches) Fig. 6. Cubic feet of bark residual per MBM log scale from logs of various diameters (both mills A and B). [24] CO ^ 2000 Q- .9- 1i -Q E 3 _l: / i *. / / / "N Lumber and box ^ / \ '^ > / / / \ N / / / / > s • • ' r ^ 1234 12341234 1960 1961 1962 Fig. 7. Shipment of products — remanufacturing plant (quarterly averages). REMANUFACTURING RESIDUES Figure 7 presents the pulpwood shipments from the plants and the total lumber and box shipments for the past three years. There appears to be a fair degree of cor- relation between these curves. On this basis, a ratio of 0.147 ton, or 294 pounds, of chippable wood produced per MBM of wood products shipped was estab- lished. 3 Fine residues (sawdust and shav- ings), now used for fuel, were estimated to total 0. 154 ton per MBM. Remanufacturing plant residues generated on a daily production of 200 MBM Per MBM Per day Per 240-day year Chippable wood . . . 19.7 cu ft 3944.0 cu ft 946,560 cu ft Sawdust & shavings . . 308 lbs 61,600 lbs 18,784,000 lbs Discussion The residues have not been separated by species. The species composition would be approximately related to the ratio of spe- cies processed for lumber. The fluctua- tions in species processed in the past are given in figure 8. The utility and problems connected with the use of different species vary, depending on the product made. If 8 There are approximately 3,000 pounds of wood material per 200 cu ft unit of hogged wood and approximately 1,600 pounds per cord unit of trim ends. a utilization plan is adopted which is sensi- tive to species differences, considerable care will need to be exercised in planning of timber purchases and logging opera- tions to maintain the desired balance. As is shown in the table giving chippable and bark residual per MBM as affected by log diameter, a change in log diameters proc- essed significantly affects the volume of residues available. If a shift does occur in log diameters processed, residue projec- tions should be adjusted in accordance with this table. [25] ^ 4000 CO 1 c 0) E 3000 Q. IE CO Total ■■ White f.r 1 1 - Pine __ Douglas-fir / 1 1 1 1 \ *.— - I t r— - f r \ i \ t LA ft / \ / / 1 1 1 1 s i / V i 1 / "■^ \ 1 f j [ V^ > /\ 7~~-zfi /V, l7 £ \^ ^ A /T *H \J V .---'-' \ / • / \ /\ \ .^■^ k * y\ / \ '^V, w \ / t _^~ x ^f. X F-b May Aug Nov Feb May Aug Nov F«b May Aug Nov Feb May Aug Nov I960 1961 1962 1963 Fig. 8. Monthly lumber shipments by species — remanufacturing plant. Selected bibliography on residue surveys Anonymous 1957. Conversion factors for Pacific Northwest forest products. Univ. of Washington Inst, of For. Prod. Batori, S. M. 1957. Wood equivalents — logs to boards, plywoods, and products from residuals. Amer. Soc. Mech. Engrs. Paper 57-SA-88. 8 pp. Carpenter, R. D. 1950. Amount of chippable waste at Southern Pine sawmills. New Orleans, La., Southern For. Exp. Sta., Occasional Paper 115. Corder, S. E. 1964. Mill residues in Jackson and Josephine counties in 1962. Oregon State Univ. For. Res. Lab. Inf. Cir. 19. May, R. H., and L. N. Ericksen 1955. Wood residue from primary wood-using industries in California. Calif. For. & Range Exp. Sta. Tech. Paper 13. Sarvis, J. C. 1959. Bark utilization study. Portland, Ore., West Pine Assn. Res. Note 7.221. 1 1 pp. Shelton, N. T. 1954. Chip yield and materials balance as related to log size in the California pine and fir region. For. Prod. Jour. 6(8) : 281-84. [26] To simplify the information, it is sometimes necessary to use trade names of products or equip- ment. No endorsement of named products is intended nor is criticism implied of similar products not mentioned. 7 1 / 2 m-10,'65(F5045)J.F.