| 1. |
- Barbosa, Leo, et al.
(författare)
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Gold mineralization in the Lappberget deposit, Garpenberg mine, Sweden: towards a geometallurgical approach
- 2022
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Ingår i: Geological Society of Sweden, 150 year anniversary meeting: Abstract volume. ; , s. 116-117
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This study investigates the mineralogy and texture of gold-bearing phases in the Lappberget deposit, Garpenberg Mine, and how these characteristics affect gold recovery during mineral processing. Multiple methods such as optical microscopy, SEM-EDS, EPMA, LA-ICP-MS, and bulk chemical analysis were applied on drill core samples, and samples from the processing plant’s Knelson gravity concentrator. Electrum-type alloys were recognized as the most common gold hosts.
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| 2. |
- Barbosa, Leo, et al.
(författare)
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Gold occurrence in the footwall of the Lappberget Deposit, Garpenberg Mine, Sweden: Implications for recovery efficiency
- 2024
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Ingår i: Ore Geology Reviews. - : Elsevier. - 0169-1368 .- 1872-7360. ; 171
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Tidskriftsartikel (refereegranskat)abstract
- By-product metals have a significant potential to bring additional economic benefits to mines. However, a detailed characterization of their distribution is generally required to fulfill this potential and should preferably be integrated into a geometallurgical assessment. This contribution presents a detailed mineralogical and textural investigation of gold-bearing phases at the footwall of the Zn–Pb–Ag–(Cu–Au) Lappberget Deposit, Garpenberg Mine, Sweden, using optical microscopy, scanning electron microscope with energy dispersive spectroscopy (SEM-EDS), electron probe microanalysis (EPMA), laser ablation-inductively coupled plasma mass spectrometer (LA-ICPMS), and bulk chemical analysis applied to drill core and Knelson concentrator samples. Gold is a by-product at the Garpenberg mine, but it is unclear how the mineralogy, occurrence, and distribution of gold-bearing phases impact on gold recoveries during mineral processing. Our results show that Au-dominant electrum is the most abundant gold-bearing phase in the footwall of the Lappberget deposit, occurring strongly associated to sulfides in a variety of textures and grain sizes. Electrum grains commonly occur within sulfide borders, as inclusions, intergrowth and overgrowths of chalcopyrite, pyrite, galena, sphalerite, and pyrrhotite. Gangue minerals may also contain disseminated electrum and inclusions. Electrum grain sizes range from ∼5 µm to 300 µm, predominantly below 100 µm. The potential of sulfide lattice-bound invisible gold in the form of solid-solution gold and colloidal gold was also investigated, showing Au depletion within the analyzed sulfide carriers. The analysis of the concentrate samples from the Knelson gravity concentrator showed 584 and 431 ppm of gold content. High degree of liberation is observed among the gold-bearing phases in the concentrate, and gold recovery is highest among fractions coarser than 106 µm mesh. Pyrite and galena are the most abundant minerals in the concentrate samples. The gold-bearing phases were categorized based on its mineralogy, texture, grain size, and association and their influence on gold processing, especially textures and grain size, which implicates its liberation in milling and recovery by the gravity separator.
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| 3. |
- Firsching, Markus, et al.
(författare)
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REWO-SORT Sensor Fusion for Enhanced Ore Sorting: a Project Overview
- 2019
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Ingår i: Procemin GEOMET 2019. - : GECAMIN.
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Konferensbidrag (refereegranskat)abstract
- Among the numerous challenges recently confronting the mining industry is the need to process ore with successively lower grades due to the continuous depletion of high-grade deposits. This increases the consumption of energy and water and, thus, the operational costs at a mine site. Multimodal sorting represents a promising technique to achieve pre-concentration of valuable minerals already at an early stage in the metallurgical process.In the ERA-MIN2 project “Reduction of Energy and Water Consumption of Mining Operations by Fusion of Sorting Technologies LIBS and ME-XRT” (REWO-SORT), a fusion technology including laser-induced breakdown spectroscopy (LIBS) and multi energy X-ray transmission (ME-XRT) is being developed by a multidisciplinary expert consortium. The project aims at classifying crushed mineral particles on a conveyor belt with the aid of deep learning technologies. In addition, the operating conditions to work with high throughput while keeping a particle monolayer on the conveyor belt have been identified. The latter objective is addressed using discrete element method (DEM) simulations. Parameter calibrations were experimentally obtained using a copper sulfide ore from the Rafaela mining company (Chile). The combination of LIBS and ME-XRT is promising, as they complement each other regarding analytical and particle selection capabilities: LIBS can provide an elemental analysis of the sample surface, while ME-XRT produces volumetric data with lower accuracy. Both sensors will be combined to extrapolate accurate and representative volumetric data, thereby securing an optimal particle selection at high throughputs. First measurements and analyses of ore samples using LIBS and ME-XRT, as well as their correlation with the Cu concentration obtained by reference lab analysis will be presented and discussed. Preliminary DEM studies indicate the existence of a threshold of conveyor belt surface area covered with particles of around 85%. Above this value the particle monolayer cannot be maintained, imposing another restriction for the speed of sensor analysis.
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| 4. |
- Guntoro, Pratama Istiadi, 1993-, et al.
(författare)
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Application of machine learning techniques in mineral phase segmentation for X-ray microcomputed tomography (µCT) data
- 2019
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- X-ray microcomputed tomography (µCT) offers a non-destructive three-dimensional analysis of ores but its application in mineralogical analysis and mineral segmentation is relatively limited. In this study, the application of machine learning techniques for segmenting mineral phases in a µCT dataset is presented. Various techniques were implemented, including unsupervised classification as well as grayscale-based and feature-based supervised classification. A feature matching method was used to register the back-scattered electron (BSE) mineral map to its corresponding µCT slice, allowing automatic annotation of minerals in the µCT slice to create training data for the classifiers. Unsupervised classification produced satisfactory results in terms of segmenting between amphibole, plagioclase, and sulfide phases. However, the technique was not able to differentiate between sulfide phases in the case of chalcopyrite and pyrite. Using supervised classification, around 50–60% of the chalcopyrite and 97–99% of pyrite were correctly identified. Feature based classification was found to have a poorer sensitivity to chalcopyrite, but produced a better result in segmenting between the mineral grains, as it operates based on voxel regions instead of individual voxels. The mineralogical results from the 3D µCT data showed considerable difference compared to the BSE mineral map, indicating stereological error exhibited in the latter analysis. The main limitation of this approach lies in the dataset itself, in which there was a significant overlap in grayscale values between chalcopyrite and pyrite, therefore highly limiting the classifier accuracy.
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| 5. |
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| 6. |
- Tiu, Glacialle
(författare)
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Geometallurgy of a complex ore : Lappberget Zn-Pb-Ag-(Cu-Au) deposit, Garpenberg mine, Sweden
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Complex ores, in this instance, a polymetallic base metal ore with additional precious and penalty elements, pose particularly tough challenges for successful production forecasts. Plant performance and recoveries for complex ores are more difficult to predict due to the larger number of variables that must be considered, tracked, and characterized during the multi-stage separation process.The focus of this study is to evaluate the mineralogical and textural controls that affect the variability in the flotation performance of a complex and variable ore. The research is based on a case study of the polymetallic Lappberget Zn-Pb-Ag-(Cu-Au) massive sulfide deposit at the Garpenberg Mine in Sweden. The mine is currently operated by Boliden Mineral AB and produces four different concentrates: zinc, lead, copper, and agravimetric concentrate targeted for gold and silver.Geometallurgical characterization was conducted to understand the variability within the Lappberget deposit and to quantify the impact of geology (e.g., host rocks, mineralogy, and texture) on the metallurgical response and metal recovery processes. The approach undertaken is divided into five stages: (1) geological characterization, (2) ore classification, (3) geometallurgical testing, (4) development of prediction models, and (5) geometallurgical domaining. The first two stages aim at characterizing the geological characteristics of the ore and understanding its variability, whereas the latter three stages aim to describe and quantify the variability in the flotation performance of the ore and determine how it relates to its geological characteristics.For the geological characterization, qualitative and quantitative mineralogical and textural investigations were undertaken for the different sulfides present in the deposit, mainly sphalerite, pyrite, galena, and chalcopyrite. Results from this study revealed the mineralogical, textural, and chemical variations of these sulfides within the deposit. This heterogeneity reflects the complex ore-forming conditions and the polyphase history of tectono-metamorphic processes that have affected the deposit. Three sphalerite types and four pyrite types were identified based on their distinct mineral chemistry, trace element signatures, texture, and host rock associations.Based on the geological characteristics of the Lappberget deposit, ten geological domains were established to provide a framework for understanding the variability in flotation performance within the deposit. Batch flotation tests were conducted for samples from each geological domain. Quantified mineralogical characterization of the flotation products from the batch flotation tests was undertaken using automated mineralogy complemented by electron microprobe analysis. Results from the deportment study of the silver-rich ore type revealed a variety of complexly intergrown silver-bearing minerals: mainly native silver, allargentum, and freibergite. A strong association between silver and antimony was also observed. The results of the sphalerite deportment study indicate that in terms of ore mineral characteristics, physical factors, such as grain size and liberation, have a more significant effect on sphalerite flotation than the presence of elevated iron and manganese in the sphalerite crystal structure. The high variability in the feed grade of the different ore types identified in the Lappberget deposit reflects the heterogeneity of the ore and, consequently, the variable flotation performance.
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| 7. |
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| 8. |
- Tiu, Glacialle, et al.
(författare)
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Ore mineral characteristics as rate-limiting factors in sphalerite flotation: Comparison of the mineral chemistry (iron and manganese content), grain size, and liberation
- 2022
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 185
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Tidskriftsartikel (refereegranskat)abstract
- A sphalerite deportment study using QEMSCAN® was conducted to understand the distribution of the sphalerite grains with varying iron and manganese content during a multi-stage Zn-Pb-Cu flotation of a complex ore. In addition, the study aims to understand the effect of sphalerite chemistry in relation to grain size and liberation. Mineral chemistry, grain size, and degree of liberation were extracted for 497,704 sphalerite grains, composed of approximately 31 million energy-dispersive spectrometer (EDS) analysis points. Bulk chemical assay and electron probe microanalysis (EPMA) were used to validate the extracted sphalerite chemistry data from QEMSCAN®. Sphalerite recovery in the final zinc concentrate improved with increasing iron and manganese content for sphalerite grains containing up to 9% Fe and 2% Mn. At higher iron and manganese content, sphalerite recovery decreased or plateaued. Conversely, an opposite trend was observed for losses to the copper-lead concentrate. The obtained results indicated that considering the ore mineral characteristics, physical factors such as grain size and liberation have a more significant effect on sphalerite flotation than the presence of iron and manganese.
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| 9. |
- Tiu, Glacialle, et al.
(författare)
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Ore mineralogy and trace element (re)distribution at the metamorphosed Lappberget Zn-Pb-Ag-(Cu-Au) deposit, Garpenberg, Sweden
- 2021
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Ingår i: Ore Geology Reviews. - : Elsevier. - 0169-1368 .- 1872-7360. ; 135
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Tidskriftsartikel (refereegranskat)abstract
- Qualitative and quantitative mineralogical and textural investigations were undertaken for the different sulfide minerals in the 1.89 Ga Lappberget deposit, with a focus on sphalerite and pyrite. Three sphalerite types were identified and associated with: (1) main massive sulfide mineralization, (2) Fe-Mn skarn ore, and (3) Ag-rich fissure veins. Sphalerite-1 contained a relatively higher amount of trace elements (Fe, Co, Ge, Cu, Sn, and Au) but is lower in Mn/Fe, Ga, and Hg compared to sphalerite-2. Evidence of tectono-metamorphic modification of sulfides is observed throughout the deposit, such as the formation of growth twins and deformation twins in sulfides, the development of high-angled triple-point junctions in recrystallized pyrite and sphalerite, and the formation of ‘ball ore’ or ‘durchbewegung’ textures within mineralized shear zones. The recrystallization of pyrite and galena may have led to the re-distribution of fluid-mobile elements (As, Cu, Zn, Pb, Ag, and Au), some of which were deposited in discordant Ag-rich fissure veins peripheral to the main massive sulfide lenses. Trace element signatures of sulfides in Lappberget are compatible with the other metamorphosed and deformed, subseafloor volcanogenic carbonate replacement (SVALS)-type deposits in the Bergslagen mining district.
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| 10. |
- Tiu, Glacialle, et al.
(författare)
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Quantifying the variability of a complex ore using geometallurgical domains
- 2023
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Ingår i: Minerals Engineering. - : Elsevier. - 0892-6875 .- 1872-9444. ; 203
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Tidskriftsartikel (refereegranskat)abstract
- This comprehensive study focuses on the geometallurgical characterization of the complex Lappberget polymetallic Zn-Pb-Ag-(Cu-Au) sulfide deposit at the Garpenberg mine, one of Sweden’s largest and most significant sources of zinc, lead, and silver. The research explores the intricate mineralogy and texture of the ore, investigating its impact on the variability of flotation performance for different ore types. QEMSCAN® analysis and element-to-mineral conversion (EMC) were employed to quantitatively characterize the ore in terms of mineral distribution and occurrence. The study revealed significant variability in Cu-Pb flotation compared to Zn flotation due to the targeted mineral varieties. While zinc primarily occurred in sphalerite grains, Cu-Pb flotation aimed to recover multiple Pb-, Cu-, Ag- and Au-bearing minerals that were finely grained and intricately intergrown with other sulfides. Grain size and the degree of liberation emerged as primary rate-limiting factors, especially in the Zn flotation circuit. Seven geometallurgical domains were defined based on the concentration efficiencies (i.e., selectivity and recovery) for sphalerite, galena, chalcopyrite, and Ag-bearing phases. The proposed geometallurgical characterization approach aims to transform geologically defined classes into geometallurgical domains by relating the deposit's key mineralogical and textural characteristics to metallurgical performance.
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