Multi-Scale X-Ray Computed Tomography Analysis to Aid Automated Mineralogy in Ore Geology Research

Ore characterization is crucial for efficient and profitable production of mineral products from an ore deposit. Analysis is typically performed at various scales (meter to microns) in a sequential fashion, where sample volume is reduced with increasing spatial resolution due to the increasing costs and run times of analysis. Thus, at higher resolution, sampling and data quality become increasingly important to represent the entire ore deposit. In particular, trace metal mineral characterization requires high-resolution analysis, due to the typical very fine grain sizes (sub-millimeter) of trace metal minerals. Automated Mineralogy (AM) is a key technique in the mining industry to quantify process-relevant mineral parameters in ore samples. Yet the limitation to two-dimensional analysis of flat sample surfaces constrains the sampling volume, introduces an undesired stereological error, and makes spatial interpretation of textures and structures difficult. X-ray computed tomography (XCT) allows three-dimensional imaging of rock samples based on the x-ray linear attenuation of the constituting minerals. Minerals are visually differentiated though not chemically classified. In this study, decimeter to millimeter large ore samples were analyzed at resolutions from 45 to 1 μm by AM and XCT to investigate the potential of multi-scale correlative analysis between the two techniques. Mineralization styles of Au, Bi-minerals, scheelite, and molybdenite were studied. Results show that AM can aid segmentation (mineralogical classification) of the XCT data, and vice versa, that XCT can guide (sub-)sampling (e.g., for heavy trace minerals) for AM analysis and provide three-dimensional context to the two-dimensional quantitative AM data. XCT is particularly strong for multi-scale analysis, increasingly higher resolution scans of progressively smaller volumes (e.g., by mini-coring), while preserving spatial reference between (sub-)samples. However, results also reveal challenges and limitations with the segmentation of the XCT data and the data integration of AM and XCT, particularly for quantitative analysis, due to their different functionalities. In this study, no stereological error could be quantified as no proper grain separation of the segmented XCT data was performed. Yet, some well-separated grains exhibit a potential stereological effect. Overall, the integration of AM with XCT improves the output of both techniques and thereby ore characterization in general.

Characterization of gold ore from Babakan Loa Sub-District and leaching study in cyanide solution

Research on the characterization of gold ore from Babakan Loa sub-district and studies of leaching in cyanide solution has been carried out. This research was conducted to determine the characteristics of gold ore from Babakan Loa and the leaching behavior in cyanide solution. The preparations carried out were crushing and grinding to obtain several size fractions. The ore characterization was carried out through XRD, XRF, SEM-EDX, and wet chemical analysis. XRD analysis results show that the main mineral phases are quartz, hematite, goethite, kaolinite, montmorillonite, and berlinite. The main constituents of the ore were Si (60.96%), Fe (10.71%), K (5.47%), and Al (19.53%). The Au content was 7.8 ppm, and the results of SEM-EDX analysis show that the gold grain size is smaller than 10µm. The leaching process showed that the highest percent gold extraction data of 92.7% was obtained in experiments with 1000 ppm sodium cyanide concentration, 10% solids percent, and 104-149µm grain size. Increasing the percentage of solids and the reduction in grain size led to a decrease in the percentage of gold extraction. The clay content was suspected to be the cause of the ineffectiveness of the leaching process in this study.

Geometallurgical ore characterization of the high-grade polymetallic unconformity-related uranium deposit

ABSTRACT Cigar Lake is a polymetallic, unconformity-related uranium deposit with complex geochemistry and mineralogy located in the eastern Athabasca Basin of northern Saskatchewan, Canada. Variable concentrations and spatial distributions of elements of concern, such as As, Mo, Ni, Co, Se, and Zr, associated with the high-grade tetravalent uranium ores [UO2+x; U(SiO4)1–x(OH)4x] present unique mining, metallurgical, and environmental challenges. Sulfide and arsenide minerals have significant control over As, Mo, Ni, Co, and Se abundances and have properties that affect element of concern mobility, thus requiring consideration during mineral processing, mine-effluent water treatment, and long-term tailings management. The U-bearing (uraninite, coffinite) and metallic arsenide (nickeline, often called “niccolite” in the past), sulfarsenide (gersdorffite, cobaltite), and sulfide (chalcopyrite, pyrite, galena, bornite, chalcocite, sphalerite, pyrrhotite) minerals provide the main controls on the distributions of the elements of concern. Arsenic, Ni, and Co occur primarily in a reduced state as 1:1 molar ratio, Ni-Co:As, arsenide, and sulfarsenide minerals such as gersdorffite, nickeline, and cobaltite. Molybdenum occurs within molybdenite and uraninite. Selenium occurs within coffinite, sulfide, and sulfarsenide minerals. Zirconium is found within detrital zircon and coffinite. The spatial distribution and paragenesis of U-, As-, and S-bearing minerals are a result of the elemental composition, pH, and redox conditions of early formational and later meteoric fluids that formed and have modified the deposit through access along lithostratigraphic permeability and tectonic structures. Using the holistic geometallurgical paradigm presented here, the geochemistry and mineral chemistry at Cigar Lake can be used to optimize and reduce risk during long-term mine and mill planning.

3D Ore Characterization as a Paradigm Shift for Process Design and Simulation in Mineral Processing

Current advances and developments in automated mineralogy have made it a crucial key technology in the field of process mineralogy, allowing better understanding and connection between mineralogy and the beneficiation process. The latest developments in X‑ray micro-computed tomography (µCT) have shown a great potential to let it become the next-generation automated mineralogy technique. µCT’s main benefit lies in its capability to allow 3D monitoring of the internal structure of the ore sample at resolutions down to a few hundred nanometers, thus excluding the common stereological error in conventional 2D analysis. Driven by the technological and computational progress, µCT is constantly developing as an analysis tool and successively it will become an essential technique in the field of process mineralogy. This study aims to assess the potential application of µCT systems, for 3D ore characterization through relevant case studies. The opportunities and platforms that µCT 3D ore characterization provides for process design and simulation in mineral processing are presented.

Maghemite in Brazilian Iron Ores: Quantification of the Magnetite-Maghemite Isomorphic Series by Χ-ray Diffraction and the Rietveld Method, and Confirmation by Independent Methods

Maghemite (γ-Fe2O3) is a mineral formed from magnetite oxidation at low temperatures, an intermediate metastable term of the magnetite to hematite oxidation and could be mixed with both. It has magnetic susceptibility similar to magnetite, crystal structure close to magnetite with which it forms a solid solution, while compositionally it equals hematite. Maghemite is thus easily misidentified as magnetite by Χ-ray diffraction and/or as hematite by spot chemical analysis in iron ore characterization routines. Nonstoichiometric magnetite could be quantified in samples of Brazilian soils and iron ores by the Rietveld method using a constrained refinement of the Χ-ray patterns. The results were confirmed by reflected light microscopy and Raman spectroscopy, thus qualitatively validating the method. Χ-ray diffraction with the refinement of the isomorphic substitution of Fe2+ by Fe3+ along the magnetite-maghemite solid solution could help to suitably characterize maghemite in iron ores, allowing for the evaluation of its ultimate influence on mineral processing, as its effect on surface and breakage properties.

Maghemite in Brazilian Iron Ores: Quantification of the Magnetite-Maghemite Isomorphic Series by X-ray Diffraction and the Rietveld Method, and Confirmation by Independent Methods

Maghemite (γ-Fe2O3) is a mineral formed from magnetite oxidation at low temperatures, an intermediate metastable term of the magnetite to hematite oxidation and could be mixed with both. It has magnetic susceptibility similar to magnetite, crystal structure close to magnetite with which it forms a solid solution, while compositionally it equals hematite. Maghemite is thus easily misidentified as magnetite by X-ray diffraction and/or as hematite by spot chemical analysis in iron ore characterization routines. Nonstoichiometric magnetite could be quantified in samples of Brazilian soils and iron ores by the Rietveld method using a constrained refinement of the X-ray patterns. The results were confirmed by reflected light microscopy and Raman spectroscopy, thus qualitatively validating the method. X-ray diffraction with the refinement of the isomorphic substitution of Fe2+ by Fe3+ along the magnetite-maghemite solid solution could help to suitably characterize maghemite in iron ores, allowing for the evaluation of its ultimate influence on mineral processing, by affecting its surface and breakage properties.

Studi Ekstraksi Bijih Emas Asal Pesawaran dengan Metode Pelindian Agitasi dalam Larutan Sianida

Research on the extraction of gold ore from Pesawaran, , Lampung, Indonesia, was carried out using the agitation leaching method in cyanide solution. This study aimed to obtain information on the use of conventional cyanidation methods for extracting gold from the Pesawaran gold ore. The ore preparation was carried out in the form of crushing, grinding and sieving to obtain samples with fraction sizes of -60 + 100 mesh, -100 +150 mesh, -150 + 200 mesh and -200 mesh. The ore characterization was performed using XRD, XRF, SEM-EDX, and wet chemical analysis. The XRD analysis showed that the main mineral phases were silica, hematite, aluminium hydroxide and orthoclase. The major constituents of the ore were Si (53,628%), Fe (15,996%), K (19,744%) and Al (8,045%). The Au content was determined by wet chemical analysis and was found to be 9.67 ppm. The experimental results show that the highest percentage of gold extraction of 83.33% was obtained using sodium cyanide at a concentration of 1000 ppm, a percent solids of 40% and a grain size of 200 mesh. Higher gold extraction was not achieved despite the use of a high cyanide concentration was probably because the remaining gold was not properly liberated. The results of SEM-EDX analysis showed that the gold grain size was <20 µm, while the grinding was performed only to a sieve size of -200 mesh (74 µm).

Hyperspectral drill-core imaging for ore characterization

&lt;p&gt;Mineral exploration campaigns represent an essential step in the discovery and evaluation of ore deposits required to fulfil the global demand for raw materials. Thousands of meters of drill-cores are extracted in order to characterize a specific exploration target. Hyperspectral imaging is recently being explored in the mining industry as a tool to complement traditional logging techniques and to provide a rapid and non-invasive analytical method for mineralogical characterization. The method relies on the fact that minerals have different spectral responses in specific portions of the electromagnetic spectrum. Sensors covering the visible to near-infrared (VNIR) and short-wave infrared (SWIR) are commonly used to identify and estimate the relative abundance of minerals such as phyllosilicates, amphiboles, carbonates, iron oxides and hydroxides as well as sulphates (Clark, 1999). The distribution of these mineral phases can frequently be used as a proxy for the distribution of ore minerals such as sulphides. Typical core imaging systems can acquire hyperspectral data from a whole drill-core tray in a matter of seconds. Available sensors record data in several hundreds of contiguous spectral bands at spatial resolutions around 1 mm/pixel.&lt;/p&gt;&lt;p&gt;&amp;#8203;&amp;#8203;In this work, we apply a local high-resolution mineralogical analysis, such as SEM-MLA&amp;#160;(Kern&amp;#160;et al., 2018), for a precise and exhaustive mineral mapping of some selected small samples. We then upscale these mineralogical data acquired from thin sections to drill-core scale by integrating hyperspectral imaging and machine learning techniques. Our proposed method is composed of two main steps. In the first step, after initially co-registering the hyperspectral and high-resolution mineralogical data and making a training set, a machine learning model is trained. In the second step, we apply the learned model to obtain mineral abundance and association maps over entire drill-cores.&lt;/p&gt;&lt;p&gt;&amp;#8203;&amp;#8203;The mapping is further used for the calculation of other mineralogical parameters essential to exploration and further mining stages such as modal mineralogy, mineral association, alteration indices, metal grade estimates and hardness. The proposed methodological framework is illustrated on samples collected from a porphyry type deposit, but the procedure is&amp;#160;easily adaptable to other ore types. Therefore, this approach can be integrated in the standard core-logging routine, complementing the on-site geologists and can serve as background for the geometallurgical analysis of numerous ore types. &amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#8203;&amp;#8203;&lt;/p&gt;&lt;p&gt;&amp;#8203;&amp;#8203;Clark, R. N., 1999,&amp;#160;&amp;#8220;Spectroscopy&amp;#160;of rocks and minerals, and principles of spectroscopy,&amp;#8221; in&amp;#160;Remote sensing for the earth sciences: Manual of remote sensing, vol. 3, John Wiley &amp; Sons, Inc, pp. 3&amp;#8211;58.&lt;/p&gt;&lt;p&gt;&amp;#8203;&amp;#8203;Gandhi, S. M. and Sarkar, B. C., 2016,&amp;#160;&amp;#8220;Drilling,&amp;#8221;&amp;#160;in&amp;#160;Essentials of Mineral Exploration and Evaluation, pp. 199&amp;#8211;234.&lt;/p&gt;&lt;p&gt;&amp;#8203;&amp;#8203;Kern, M., Mo&amp;#776;ckel, R., Krause, J., Teichmann, J., Gutzmer, J., 2018. Calculating the deportment of a fine-grained and compositionally complex Sn skarn with a modified approach for automated mineralogy. Miner. Eng. 116, 213&amp;#8211;225.&lt;/p&gt;

Mineral and ore characterization of the rare earth element from Khotgor deposit

Although many new deposits of rare earth elements (REEs) are being discovered, the technical and technological knowledge on the separation of REEs from its ore by concentrating procedure and concentrate treatment are limited. In Mongolia, doing research on the chemical technological characteristics of the REEs mineral and ore would have been a great importance for the academic research knowledge and creation of new documents with respect to REEs. Moreover, it can be efficiently resulted to socio-economic issue in our country. The surface rocks and ore from Khotgor deposit located in Umnugobi province were studied by electron microscopy, SEM/EDX and X-ray diffraction method. As a result, the rocks are composed to sienite protracted by carbonatite, nepheline-sienite rocks with breccially-formed, apatite (flourapatite) with 1-3%, barite, celestine, pyrite and magnetite, respectively. In the rock, REEs’s total content was about 0.02-1.6%, and its 86.2-95.7% for the cerium group elements. A nepheline sienite and sienite that includes apatite, barite, celestine, pyrite and magnetite were composed to the ore. Total content of REEs in this ore was 2.18% with light REEs about 95%. This study summarized the chemical composition of rocks, ores and minerals. Furthermore, the contents of REEs and characterization of the carrier minerals and other accompanied minerals were presented. Хотгор ордын газрын ховор элементийн хүдэр ба эрдсийн шинж чанар Хураангуй: Газрын ховор элемент (ГХЭ)-ийн олон шинэ ордууд нээгдэж байгаа ч тэдгээрийн хүдрээс ГХЭ-ийг баяжуулан ялгаж авах, баяжмалыг боловсруулах техник технологийн мэдлэг хязгаарлагдмал байгаа өнөө үед Монгол улс дахь ГХЭ-ийн хүдэр, эрдсийн химийн технологийн шинж чанарыг нарийвчлан судалж, академик судалгааны мэдлэг хуримтлуулах, баримт материал бий болгох нь нийгэм, эдийн засгийн чухал ач холбогдолтой. Өмнөговь аймгийн нутагт орших Хотгор ордын гадаргын чулуулаг ба хүдрийг электрон микроскоп, SEM/EDХ ба рентген дифракцийн аргаар судлав. Чулуулаг нь гадаргуугийн өгөршилд өртсөн сиенит ба брекчлэг бүтэц үүсгэсэн нефелин сиенит чулуулгаас тогтсон, сиенит нь карбонатитээр бага зэрэг түрэгдсэн 1-3% хүртэл апатит (фторапатит) болон барит, целестин, пирит, магнетит зэрэг эрдэс агуулж байна. Чулуулагт ГХЭ-ийн нийлбэр агууламж 0.02-1.6%, түүний 86.2-95.7% нь церийн бүлгийн элементүүдэд ноогдоно. Хүдрийн чулуулаг нь апатит (фторапатит) болон барит, целестин, пирит, магнетит зэрэг эрдэс агуулсан сиенит ба нефелин сиенит, ГХЭ-ийн нийлбэр агууламж 2.18%, мөн түүний 95%-ийг хөнгөн ГХЭ-үүд эзэлж байна. Энэхүү судалгаанд чулуулаг, хүдэр, эрдсүүдийн химийн бүрдэл, ГХЭ-ийн агууламж, тээгч ба дагалдах зарим эрдсүүдийн шинж чанарыг судалсан үр дүнгээс оруулав.Түлхүүр үг: нефелин,сиенит, апатит, фторапатит