Sci. Dril., 19, 13–16, 2015 www.sci-dril.net/19/13/2015/ doi:10.5194/sd-19-13-2015 © Author(s) 2015. CC Attribution 3.0 License. T e c h n ic a l D e v e lo p m e n ts An innovative optical and chemical drill core scanner A. S. L. Sjöqvist1, M. Arthursson1, A. Lundström1, E. Calderón Estrada1, A. Inerfeldt1, and H. Lorenz2 1Minalyze AB, Industrivägen 4, 433 61 Sävedalen, Sweden 2Department of Earth Sciences, Uppsala University, Villavägen 16, 752 36 Uppsala, Sweden Correspondence to: A. S. L. Sjöqvist (axel.sjoqvist@minalyze.com) Received: 16 February 2015 – Revised: 9 April 2015 – Accepted: 13 April 2015 – Published: 29 May 2015 Abstract. We describe a new innovative drill core scanner that semi-automatedly analyses drill cores directly in drill core trays with X-ray fluorescence spectrometry, without the need for much sample preparation or operator intervention. The instrument is fed with entire core trays, which are photographed at high resolution and scanned by a 3-D profiling laser. Algorithms recognise the geometry of the core tray, number of slots, location of the drill cores, calculate the optimal scanning path, and execute a continuous XRF analysis of 2 cm width along the core. The instrument is equipped with critical analytical components that allow an effective QA/QC routine to be implemented. It is a mobile instrument that can be manoeuvred by a single person with a manual pallet jack. 1 Introduction Rapid decision-making and a continuous re-evaluation are the key to successful commercial and scientific drilling projects. Geochemical information of drill cores is impor- tant base information for many projects and crucial for cer- tain applications, like exploration and mining drilling. A ma- jor drawback is that performing geochemical analyses takes time. Thus, expensive rig time is often spent while waiting for results, and decisions might be made with only incom- plete background information at hand. An in-depth analy- sis of the drilling industry has revealed that access to even rudimentary geochemical information in an early stage af- ter drilling has substantial advantages for the planning and implementation of the subsequent scientific and analytical work. A concept instrument was envisioned, which would anal- yse drill cores with a non-destructive methodology and min- imal interference with other on-site work in terms of time and labour. Since drill cores are handled in core trays with multiple slots, the processing of whole core trays (compared to individual sections) is an efficient way to analyse great lengths of drill core. The first step was to prove the reliabil- ity of using an in situ non-destructive analytical technology on drill core surfaces. The prototype instrument (for 0.5 m long sections) demonstrated with the successful analysis of more than 22 km of drill core that energy-dispersive X-ray spectrometry on drill core surface is a viable approach. After this proof of concept, the construction of the first complete system commenced in October 2013. 2 Instrument specifications and capabilities The semi-automated new drill core scanner is built with flex- ibility in mind (Fig. 1). More than anything else, the instru- ment is a platform that handles drill cores in core trays. The methodology of processing entire drill core trays is patented and thus unique. The composition of the drill core tray does not matter. Exactly which sensors and attachments are cou- pled to that platform depends on specific project needs and advances in analytical technology. The current set-up is de- scribed below and summarised in Table 1. 2.1 Digital photography and 3-D scanning The high-resolution RGB line scan camera produces digital photo documentation of the drill cores and trays. Digital im- ages are stored in 8 bits per channel lossless TIFF and can have a pixel resolution of up to 10 px mm−1. For reliable analytical results it is of the highest impor- tance to have accurate information about the location and ge- ometry of the samples. For this purpose a 3-D model of the core tray with its contents is created from a laser scan, per- formed at the same time as RGB imaging. Algorithms devel- Published by Copernicus Publications on behalf of the IODP and the ICDP. 14 A. S. L. Sjöqvist et al.: An innovative optical and chemical drill core scanner Figure 1. The new instrument described is a drill core scanner that intelligently handles entire drill core trays to produce chemical anal- yses of drill cores. Table 1. Technical specifications of the new instrument. Dimensions 1.8 m × 1.3 m × 1.2 m (L × W × H ) Mass ca. 1 t Electrical supply Three phase 400 V, 16 A Power consumption ca. 3 kW Cooling External, quick-connect fittings Photography, line Up to 10 px mm−1, 8 bit lossless TIFF 3-D profiling, line 1 mm × 0.34 mm × 17 µm (L × W × H ) Chemical analysis method ED-XRF Detection range, in air (Mg), Al–U Spatial resolution Down to 1 mm Normal throughput 15–20 m h−1 oped by us calculate the geometry of the core tray, the num- ber of slots, the location and geometry of drill core pieces, and the optimal path to scan without colliding the detector, which should be kept at a constant distance to the drill core. Secondary benefits of having detailed information about the drill core geometry are that the drill core length is mea- sured and cracks are semi-automatically identified, which is useful for geotechnical purposes, e.g. RQD (rock quality des- ignation) and fracture frequency. 2.2 XRF analysis In situ non-destructive chemical analyses of the drill cores are acquired through X-ray fluorescence (XRF) analysis by energy-dispersive spectrometry (EDS), using a high-quality silicon drift detector (SDD). A partial vacuum between the irradiated sample surface and the detector window protects the sensitive Be detector window from dust contamination and also reduces attenuation by the air in the lower energy range of the X-ray spectrum, thus enabling the detection of elements down to Al or Mg. X-ray tubes with different anode target materials are avail- able, e.g. Cr, Mo, and Ag. The selection of anode material depends on the project-specific analytical preferences. The X-ray beam is collimated to a linear beam that is 2 cm wide and 1 mm thick perpendicular to the drill core axis. Table 2. Specifications of the analytical parameters used for scan- ning the COSC-1 drill core with the new instrument. X-ray tube anode Cr Voltage 40 kV Current 20 mA Elemental suite Al, Si, P, S, Cl, K, Ca, Ti, Fe, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Pb Scanning speed 10 mm s−1 Analysis resolution 0.1 m Scanning is performed in a continuous motion, and the data over a certain length are integrated. The scanning speed and integration length depend on the user’s requirements for analysis precision and resolution, and the drill core’s chemi- cal composition. Confident detection of the typical major and minor elements of interest (cf. Table 2) is usually achieved with a real-time analysis of 10 s. With a typical scanning speed of 1 cm s−1 this corresponds to a distance of 10 cm. The analytical parameters, the scanning speed, and the inte- gration length for the analysis need to be evaluated and ad- justed for each project. Typical throughput is of the order of two to four drill core trays per hour, depending on the number of slots and the complexity of the scanning path, which for a six-slot drill core tray means an effective scanning through- put of approximately 15–20 m h−1. The instrument is a stand-alone system. No additional ex- ternal processing or storage capabilities are required. Chem- ical analyses are processed in real time and can be displayed on the screen while scanning. The X-ray beam location and intensity are monitored throughout the scanning process and logged to monitor in- strument drift. Two sample holders for pressed pellets or glass pucks allow easy analytical calibration and detec- tor drift measurements with matrix-matched certified refer- ence materials, or analyses of blank samples. This provides easy access to critical components for performing effective QA/QC (quality assurance/quality control) routines during an analytical campaign. 2.3 Operation, connectivity, mobility, and safety The entire instrument runs off a single three-phase plug (400 V, 16 A) and consumes approximately 3 kW. In remote areas, a diesel generator can deliver enough power. Use of a back-up uninterruptible power supply (UPS) is recom- mended to ensure operation stability. The instrument is con- veniently operated by the resistive touch screen, which can be used with any type of safety gloves. Front-end connectivity includes a 230 V socket, USB ports, and an Ethernet port. The user can connect devices that are most convenient for the moment, whether it is a USB hard disk, mouse and keyboard, Wi-Fi antenna, or 4G mobile Internet dongle. Sci. Dril., 19, 13–16, 2015 www.sci-dril.net/19/13/2015/ A. S. L. Sjöqvist et al.: An innovative optical and chemical drill core scanner 15 The bottom plate hosts furrows that allow the instrument to be lifted and moved around by a forklift truck or manual pallet jack by one person. The total mass of the system is approximately 1 t. For the sake of flexibility, the X-ray tube water-cooling system is external and connected to the instrument by quick- connect fittings. One could choose to locate the cooling sys- tem in another room or, in hot climates, to upgrade to a larger system. The radiation-blocking protective shell consists of two lay- ers of 3 mm thick steel, and the window is made of lead glass. The instrument has all necessary radiation safety re- quirements and is completely safe to work with. 3 Geoscientific applications Rock drill cores are the most tangible representations of un- exposed subsurface geology. However, drilling is expensive and the amount of sample very limited. Multiple investiga- tions on the drill core require that the number of destructive analyses is limited to the absolutely necessary. A quick and non-destructive method for obtaining geochemical informa- tion, like XRF scanning, is therefore an asset. The instru- ment, with its combination of digital photography, 3-D pro- filing, and chemical analyses, effectively creates a digital rep- resentation of the drill core, which then can be evaluated in its undisturbed original form in a virtual drill core archive. Availability of chemical information early in the process of drill core processing greatly facilitates the geological doc- umentation, making drill core logging more objective and less dependent on the individual geologist’s experience and best judgement. This is of particular importance for subse- quent and advanced studies that utilise the base scientific documentation of a project. While researchers have performed tests to analyse unpre- pared rock drill cores by XRF for a long time (Carlsson and Akselsson, 1981), in recent years unprepared rock drill cores have almost exclusively been analysed by portable/handheld XRF instruments. Portable/handheld XRF instruments are gaining popularity and have been applied widely and suc- cessfully to analyse drill cores in a non-destructive way (e.g. Gazley et al., 2011, 2012; Fisher et al., 2014; Le Vaillant et al., 2014; Ross et al., 2014). Advantages of the new instru- ment over handheld XRF instruments are a better and more representative coverage (continuous scanning vs. point anal- yses), reduced labour, standardised analytical conditions, in- tegrated routines, and advanced data handling. 4 Preliminary high-resolution chemical data from COSC-1 During October–November of 2014, the entire COSC-1 drill core (Collisional Orogeny in the Scandinavian Caledonides ICDP; cf. Lorenz et al., 2015) was scanned with the new D ril le r’s de pt h [m ] SiO2 0 100% P2 5O 0 0.1% S 0 3% Cl 0 0.1% K2O 0 6% CaO 0 40% Al2O3 0 20% TiO2 0 3% Fe2O3 0 15% 500 1500 1000 2000 Figure 2. Preliminary chemical data of major elements produced by the new instrument of the full length of the COSC-1 drill core, scanned with 0.1 m resolution. www.sci-dril.net/19/13/2015/ Sci. Dril., 19, 13–16, 2015 16 A. S. L. Sjöqvist et al.: An innovative optical and chemical drill core scanner instrument described here. The ca. 2400 m of drill core, whereof ca. 1500 m in H size (76 mm diameter) and 900 m in N size (47.8 and 45 mm), are boxed in 719 core trays with four slots for HQ and five compartments for NQ. The analyt- ical parameters are described in Table 2. A preliminary as- sessment of the analytical precision yields an estimated pre- cision for major elements better than 5–10 % and better than 20 % for most trace elements. The COSC-1 drill core consists of mainly high-grade metamorphosed siliceous sedimentary rocks. Felsic, calc- silicate, and amphibole gneisses are typical representatives, with marbles, amphibolites, and subordinate porphyries. The lower part of the core is dominated by the mylonites of a ma- jor thrust zone. A first assessment of the preliminary XRF data (Fig. 2) shows an increase in SiO2 with depth and that elevated levels of Cl and P2O5 occur in the thrust zone, possi- bly introduced by fluids. High CaO content and associated el- evated Sr levels in the upper and middle part of the drill core can be linked to marbles and possibly calc-silicate gneisses, which become less frequent in the lower part. Peaks in the density, P wave velocity, and rock resistivity downhole logs seem to correlate with low SiO2 values of amphibolites. A more detailed assessment of the data produced by the new instrument started with the utilisation XRF data during the COSC-1 sampling party in Berlin, 2–6 February 2015, where they helped the scientists to select their sampling spots. 5 Summary A new instrument provides fast, non-destructive chemical analyses of drill cores in drill core trays by automated scan- ning XRF. The mobile and autonomous system can be moved and operated anywhere in the world. Drill cores are docu- mented by high-resolution digital photography and 3-D laser profiling. 3-D topographic information is used to calculate the optimal scanning path automatically, and for length and structural measurements of the drill core. The instrument allows scientists to obtain basic chemical data early in a project, e.g. on the drill site where the analyses immediately become available to geologists. Subsequently, core logging is less subjective and less dependent on the individual’s expe- rience. Non-destructive XRF analyses leave more of the drill core to be used for other studies. In addition, a digital copy of the drill core can be stored in a virtual drill core archive in which drill cores can be (re)evaluated in their original state. Acknowledgements. Minalyze wishes to acknowledge B. Arthursson, N. Bragsjö, M. Halonen, E. Hegardt, L. Hellberg, C. Johansson, V. Krpo, V. Kunavuti, A. Nordlund, J. Nordstrand, M. Rostedt, C. Sernevi, A. Smajic, and I. Zagerholm, who have played a role in developing the drill core scanner called Minalyzer CS from concept to functional instrument. Edited by: U. Harms Reviewed by: U. Harms and A. Schleicher References Carlsson, L.-E. and Akselsson, R.: Applicability of PIXE and XRF to fast drill core analysis in air, Adv. X Ray Anal., 24, 313–321, http://lup.lub.lu.se/record/2026610, 1981. Fisher, L., Gazley, M. F., Baensch, A., Barnes, S. J., Cleverley, J., and Duclauz, G.: Resolution of geochemical and lithostrati- graphic complexity: a workflow for application of portable X-ray fluorescence to mineral exploration, Geochem.-Explor. Env. A., 14, 149–159, doi:10.1144/geochem2012-158, 2014. Gazley, M. F., Vry, J. K., du Plessis, E., and Handler, M. R.: Application of portable X-ray fluorescence anal- yses to metabasalt stratigraphy, Plutonic Gold Mine, Western Australia, J. Geochem. Explor., 110, 74–80, doi:10.1016/j.gexplo.2011.03.002, 2011. Gazley, M. F., Duclaux, G., Fisher, L. A., Beer, S. de, Smith, P., Taylor, M., Swanson, R., Hough, R. M., and Cleverley, J. S.: 3D visualisation of portable X-ray fluorescence data to improve ge- ological understanding and predict metallurgical performance at Plutonic Gold Mine, Western Australia, T. I. Min. Metall. B, 120, 88–96, doi:10.1179/1743275812Y.0000000002, 2012. Le Vaillant, M., Barnes, S. J., Fisher, L., Fiorentini, M. L., and Caruso, S.: Use and calibration of portable X-ray fluo- rescence analysers: application to lithogeochemical exploration for komatiite-hosted nickel sulphide deposits, Geochem.-Explor. Env. A., 14, 199–209, doi:10.1144/geochem2012-166, 2014. Lorenz, H., Rosberg, J.-E., Juhlin, C., Bjelm, L., Almqvist, B. S. G., Berthet, T., Conze, R., Gee, D. G., Klonowska, I., Pascal, C., Pedersen, K., Roberts, N., and Tsang, C.: Operational Report about Phase 1 of the Collisional Orogeny in the Scandinavian Caledonides scientific drilling project (COSC-1), Sci. Dril., in review, 2015. Ross, P.-S., Bourke, A., and Fresia, B.: Improving lithological dis- crimination in exploration drill-cores using portable X-ray fluo- rescence measurements: (1) testing three Olympus Innov-X anal- ysers on unprepared cores, Geochem.-Explor. Env. A., 14, 171– 185, doi:10.1144/geochem2012-163, 2014. Sci. Dril., 19, 13–16, 2015 www.sci-dril.net/19/13/2015/ http://lup.lub.lu.se/record/2026610 http://dx.doi.org/10.1144/geochem2012-158 http://dx.doi.org/10.1016/j.gexplo.2011.03.002 http://dx.doi.org/10.1179/1743275812Y.0000000002 http://dx.doi.org/10.1144/geochem2012-166 http://dx.doi.org/10.1144/geochem2012-163 Abstract Introduction Instrument specifications and capabilities Digital photography and 3-D scanning XRF analysis Operation, connectivity, mobility, and safety Geoscientific applications Preliminary high-resolution chemical data from COSC-1 Summary Acknowledgements References