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Applications of SEM Automated Mineralogy: From Ore Deposits over Processing...
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Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: closed (15 February 2020) | Viewed by 78562

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Prof. Dr. Bernhard Schulz

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Guest Editor
Department of Economic Geology and Petrology, Technische Universität Bergakademie Freiberg, D-09599 Freiberg, Germany
Interests: metamorphic geology (metapelites, metabasites); monazite dating by EPMA; geothermobarometry; Paleozoic and Proterozoic orogens; application of SEM-based automated mineralogical methods (Mineral Liberation Analysis/MLA); mineral resources; analytical methods with SEM and EPMA

Special Issue Information

Dear Colleagues,

During the last decade, software developments in Scanning Electron Microscopy (SEM) provoked a notable increase of applications to the study of solid matter. The mineral liberation analysis (MLA) of processed metal ores was an important drive for innovations that led to QEMSCAN, MLA and other software platforms. These combine the assessment of the backscattered electron (BSE) image to the directed steering of the electron beam for energy dispersive spectroscopy (EDS) to automated mineralogy. However, despite a wide distribution of SEM instruments in material research and industry, the potential of SEM automated mineralogy is still under-utilised. The characterisation of primary ores, and the optimisation of comminution, flotation, mineral concentration and metallurgical processes in the mining industry by generating quantified data, is still the major application field of SEM automated mineralogy. However, there is interesting potential beyond these classical fields of geometallurgy and metal ore fingerprinting. Slags, pottery and artefacts can be studied in an archeological context for the recognition of provenance and trade pathways; soil, and solid particles of all kinds, are objects in forensic science. SEM automated mineralogy allows new insight in the fields of process chemistry and recycling technology.

We request articles dealing with the applications of SEM automated mineralogy to solid matter, material and particle analysis, in geosciences, process mineralogy, chemical technology, recycling, environmental sciences, forensic science and archeometry, and in combination with other analytical methods.

Prof. Dr. Bernhard Schulz
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Minerals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Scanning electron microscope (SEM)
  • Process mineralogy
  • Mineral liberation analysis
  • Geometallurgy
  • Geosciences
  • Mineral deposits
  • Resource technology

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Published Papers (11 papers)

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Editorial

Jump to: Research, Review

5 pages, 204 KiB  
Editorial
Editorial for Special Issue “Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization”
by Bernhard Schulz
Minerals 2020, 10(12), 1103; https://doi.org/10.3390/min10121103 - 9 Dec 2020
Cited by 2 | Viewed by 2010
Abstract
Matter is particulate [...] Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)

Research

Jump to: Editorial, Review

12 pages, 4862 KiB  
Article
An Improved Evaluation Strategy for Ash Analysis Using Scanning Electron Microscope Automated Mineralogy
by Andrea C. Guhl, Valentin-G. Greb, Bernhard Schulz and Martin Bertau
Minerals 2020, 10(5), 484; https://doi.org/10.3390/min10050484 - 25 May 2020
Cited by 7 | Viewed by 3453
Abstract
Sewage slush ashes are materials composed of polyphase particles. Ashes are fine-grained with many amorphous components, and analytical techniques such as X-ray diffractometry cannot recover all the properties. For sewage sludge ash, treatment often focuses on phosphate recovery. Automated mineralogy techniques were applied [...] Read more.
Sewage slush ashes are materials composed of polyphase particles. Ashes are fine-grained with many amorphous components, and analytical techniques such as X-ray diffractometry cannot recover all the properties. For sewage sludge ash, treatment often focuses on phosphate recovery. Automated mineralogy techniques were applied in order to study phosphate associations and their behavior towards chemical processes. This work shows the distribution of phosphate content in sewage sludge ash and identifies the main recovered phosphate phases in acid leaching. Data interpretation was focused on the target material, phosphate. The approach documents spectra labelling with respect to one target component, phosphorus. This is a tool for assessing sewage sludge ashes towards their phosphate recovery potential and highlights issues processing needs to address. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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33 pages, 4781 KiB  
Article
Exploration Potential of Fine-Fraction Heavy Mineral Concentrates from Till Using Automated Mineralogy: A Case Study from the Izok Lake Cu–Zn–Pb–Ag VMS Deposit, Nunavut, Canada
by H. Donald Lougheed, M. Beth McClenaghan, Dan Layton-Matthews and Matthew Leybourne
Minerals 2020, 10(4), 310; https://doi.org/10.3390/min10040310 - 30 Mar 2020
Cited by 18 | Viewed by 5531
Abstract
Exploration under thick glacial sediment cover is an important facet of modern mineral exploration in Canada and northern Europe. Till heavy mineral concentrate (HMC) indicator mineral methods are well established in exploration for diamonds, gold, and base metals in glaciated terrain. Traditional methods [...] Read more.
Exploration under thick glacial sediment cover is an important facet of modern mineral exploration in Canada and northern Europe. Till heavy mineral concentrate (HMC) indicator mineral methods are well established in exploration for diamonds, gold, and base metals in glaciated terrain. Traditional methods rely on visual examination of >250 µm HMC material, however this study applies modern automated mineralogical methods (mineral liberation analysis (MLA)) to investigate the finer (<250 µm) fraction of till HMC. Automated mineralogy of finer material allows for rapid collection of precise compositional and morphological data from a large number (10,000–100,000) of heavy mineral grains in a single sample. The Izok Lake volcanogenic massive sulfide (VMS) deposit, one of the largest undeveloped Zn–Cu resources in North America, has a well-documented fan-shaped indicator mineral dispersal train and was used as a test site for this study. Axinite, a VMS indicator mineral difficult to identify optically in HMC, is identified in till samples up to 8 km down ice. Epidote and Fe-oxide minerals are identified, with concentrations peaking proximal to mineralization. Corundum and gahnite are intergrown in till samples immediately down ice of mineralization. Till samples also contain chalcopyrite and galena up to 8 km down ice of mineralization, an increase from 1.3 km for sulfide minerals in till previously reported for coarse HMC fractions. Some of these sulfide grains occur as inclusions within chemically and physically robust mineral grains and would not be identified visually in the coarse HMC visual counts. Best practices for epoxy mineral grain mounting and abundance reporting are presented along with the automated mineralogy of till samples down ice of the deposit. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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19 pages, 11496 KiB  
Article
Evaluation of Recyclability of a WEEE Slag by Means of Integrative X-Ray Computer Tomography and SEM-Based Image Analysis
by Markus Buchmann, Nikolaus Borowski, Thomas Leißner, Thomas Heinig, Markus A. Reuter, Bernd Friedrich and Urs A. Peuker
Minerals 2020, 10(4), 309; https://doi.org/10.3390/min10040309 - 30 Mar 2020
Cited by 16 | Viewed by 4462
Abstract
Waste of electrical and electronic equipment (WEEE) is one of the fastest growing waste streams globally. Therefore, recycling of the valuable metals of this stream plays a vital role in establishing a circular economy. The smelting process of WEEE leads to significant amounts [...] Read more.
Waste of electrical and electronic equipment (WEEE) is one of the fastest growing waste streams globally. Therefore, recycling of the valuable metals of this stream plays a vital role in establishing a circular economy. The smelting process of WEEE leads to significant amounts of valuable metals and rare earth elements (REEs) trapped in the slag phase. The effective manipulation of this phase transfer process necessitates detailed understanding and effective treatment to minimize these contents. Furthermore, an adequate process control to bring these metal contents into structures that make recycling economically applicable is required. Within the present study, a typical slag from a WEEE melting process is analyzed in detail. Therefore, the material is investigated with the help of X-ray computed tomography (XCT) and scanning electron microscopy (SEM)-based mineralogical analysis (MLA) to understand the typical structures and its implications for recycling. The influencing factors are discussed, and further processing opportunities are illustrated. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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29 pages, 11604 KiB  
Article
Automated Quantitative Mineralogy Applied to Metamorphic Rocks
by Nynke Keulen, Sebastian Næsby Malkki and Shaun Graham
Minerals 2020, 10(1), 47; https://doi.org/10.3390/min10010047 - 3 Jan 2020
Cited by 20 | Viewed by 6273
Abstract
The ability to apply automated quantitative mineralogy (AQM) on metamorphic rocks was investigated on samples from the Fiskenæsset complex, Greenland. AQM provides the possibility to visualize and quantify microstructures, minerals, as well as the morphology and chemistry of the investigated samples. Here, we [...] Read more.
The ability to apply automated quantitative mineralogy (AQM) on metamorphic rocks was investigated on samples from the Fiskenæsset complex, Greenland. AQM provides the possibility to visualize and quantify microstructures, minerals, as well as the morphology and chemistry of the investigated samples. Here, we applied the ZEISS Mineralogic software platform as an AQM tool, which has integrated matrix corrections and full quantification of energy dispersive spectrometry data, and therefore is able to give detailed chemical information on each pixel in the AQM mineral maps. This has been applied to create mineral maps, element concentration maps, element ratio maps, mineral association maps, as well as to morphochemically classify individual minerals for their grain shape, size, and orientation. The visualization of metamorphic textures, while at the same time quantifying their textures, is the great strength of AQM and is an ideal tool to lift microscopy from the qualitative to the quantitative level. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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12 pages, 4531 KiB  
Article
Nanoscale Automated Quantitative Mineralogy: A 200-nm Quantitative Mineralogy Assessment of Fault Gouge Using Mineralogic
by Shaun Graham and Nynke Keulen
Minerals 2019, 9(11), 665; https://doi.org/10.3390/min9110665 - 29 Oct 2019
Cited by 14 | Viewed by 3970
Abstract
Effective energy-dispersive X-ray spectroscopy analysis (EDX) with a scanning electron microscope of fine-grained materials (submicrometer scale) is hampered by the interaction volume of the primary electron beam, whose diameter usually is larger than the size of the grains to be analyzed. Therefore, mixed [...] Read more.
Effective energy-dispersive X-ray spectroscopy analysis (EDX) with a scanning electron microscope of fine-grained materials (submicrometer scale) is hampered by the interaction volume of the primary electron beam, whose diameter usually is larger than the size of the grains to be analyzed. Therefore, mixed signals of the chemistry of individual grains are expected, and EDX is commonly not applied to such fine-grained material. However, by applying a low primary beam acceleration voltage, combined with a large aperture, and a dedicated mineral classification in the mineral library employed by the Zeiss Mineralogic software platform, mixed signals could be deconvoluted down to a size of 200 nm. In this way, EDX and automated quantitative mineralogy can be applied to investigations of submicrometer-sized grains. It is shown here that reliable quantitative mineralogy and grain size distribution assessment can be made based on an example of fault gouge with a heterogenous mineralogy collected from Ikkattup nunaa Island, southern West Greenland. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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14 pages, 2846 KiB  
Article
Mineralogical Imaging for Characterization of the Per Geijer Apatite Iron Ores in the Kiruna District, Northern Sweden: A Comparative Study of Mineral Liberation Analysis and Raman Imaging
by Patrick Krolop, Anne Jantschke, Sabine Gilbricht, Kari Niiranen and Thomas Seifert
Minerals 2019, 9(9), 544; https://doi.org/10.3390/min9090544 - 10 Sep 2019
Cited by 17 | Viewed by 7987
Abstract
The Per Geijer iron oxide apatite deposits are important potential future resources for Luossavaara-Kiirunavaara Aktiebolag (LKAB) which has been continuously mining magnetite/hematite ores in northern Sweden for over 125 years. Reliable and quantitative characterization of the mineralization is required as these ores inherit [...] Read more.
The Per Geijer iron oxide apatite deposits are important potential future resources for Luossavaara-Kiirunavaara Aktiebolag (LKAB) which has been continuously mining magnetite/hematite ores in northern Sweden for over 125 years. Reliable and quantitative characterization of the mineralization is required as these ores inherit complex mineralogical and textural features. Scanning electron microscopy-based analyses software, such as mineral liberation analyzer (MLA) provide significant, time-efficient analyses. Similar elemental compositions of Fe-oxides and, therefore, almost identical backscattered electron (BSE) intensities complicate their discrimination. In this study, MLA and Raman imaging are compared to acquire mineralogical data for better characterization of magnetite and hematite-bearing ores. The different approaches demonstrate advantages and disadvantages in classification, imaging, discrimination of iron oxides, and time consumption of measurement and processing. The obtained precise mineralogical information improves the characterization of ore types and will benefit future processing strategies for this complex mineralization. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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18 pages, 5676 KiB  
Article
Automated SEM Mineral Liberation Analysis (MLA) with Generically Labelled EDX Spectra in the Mineral Processing of Rare Earth Element Ores
by Bernhard Schulz, Gerhard Merker and Jens Gutzmer
Minerals 2019, 9(9), 527; https://doi.org/10.3390/min9090527 - 30 Aug 2019
Cited by 48 | Viewed by 11242
Abstract
Many rare earth element (REE) deposits have experienced multistage geological enrichment processes resulting in REE bearing mineral assemblages of considerable complexity and variability. Automated scanning electron microscopy (SEM) mineral liberation analysis of such REE ores is confronted by the difficult assignment of energy-dispersive [...] Read more.
Many rare earth element (REE) deposits have experienced multistage geological enrichment processes resulting in REE bearing mineral assemblages of considerable complexity and variability. Automated scanning electron microscopy (SEM) mineral liberation analysis of such REE ores is confronted by the difficult assignment of energy-dispersive X-ray (EDX) spectra to REE mineral names. To overcome and bypass this problem, a generic and reliable labelling of EDX reference spectra obtained from REE-bearing minerals based on their contents of Si, Ca, F and P in a bulk normalised analysis is proposed. The labelled spectra are then combined into groups of REE-P (~monazite), REE-Ca-Si-P (~britholite), REE-Ca-F (~synchysite) and REE-F (~bastnaesite, parisite, fluocerite). Mixed spectra with low counts for REE from minute REE mineral grains are combined into a separate group. This classification scheme is applied to automated SEM mineral liberation analysis (MLA) data from beneficiation products by comminution and multistage flotation of REE carbonatite ores. Mineral modes, mineral grain size distribution, mineral liberation, mineral locking and mineral grade versus recovery curves based on the analysis of >200,000 particles in a sample can be recognised and interpreted in virtual grain size fractions. The approach as proposed here will allow future process mineralogical studies of REE deposits to be robust and comparable. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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19 pages, 10099 KiB  
Article
Automated Quantitative Mineralogy Optimized for Simultaneous Detection of (Precious/Critical) Rare Metals and Base Metals in A Production-Focused Environment
by Mathis Warlo, Christina Wanhainen, Glenn Bark, Alan R. Butcher, Iris McElroy, Dominique Brising and Gavyn K. Rollinson
Minerals 2019, 9(7), 440; https://doi.org/10.3390/min9070440 - 18 Jul 2019
Cited by 15 | Viewed by 7983
Abstract
Automated Scanning Electron Microscopy (ASEM) systems are applied in the mining industry to quantify the mineralogy of the ore feed and products. With society pushing towards sustainable mining, this quantification should be comprehensive and include trace minerals since they are often either deleterious [...] Read more.
Automated Scanning Electron Microscopy (ASEM) systems are applied in the mining industry to quantify the mineralogy of the ore feed and products. With society pushing towards sustainable mining, this quantification should be comprehensive and include trace minerals since they are often either deleterious or potential by-products. Systems like QEMSCAN® offer a mode for trace mineral analysis (TMS mode); However, it is unsuitable when all phases require analysis. Here, we investigate the potential of detecting micron-sized trace minerals in fieldscan mode using the QEMSCAN® system with analytical settings in line with the mining industry. For quality comparison, analysis was performed at a mining company and a research institution. This novel approach was done in full collaboration with both parties. Results show that the resolution of trace minerals at or below the scan resolution is difficult and not always reliable due to mixed X-ray signals. However, by modification of the species identification protocol (SIP), quantification is achievable, although verification by SEM-EDS is recommended. As an add-on to routine quantitative analysis focused on major ore minerals, this method can produce quantitative data and information on mineral association for trace minerals of precious and critical metals which may be potential by-products in a mining operation. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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23 pages, 8106 KiB  
Article
Mineralogical and Chemical Characterization of Zr-REE-Nb Ores from Khalzan Buregtei (Mongolia)—Approaches to More Efficient Extraction of Rare Metals from Alkaline Granitoids
by Lars Hans Gronen, Sven Sindern, Janet Lucja Katzmarzyk, Udo Bormann, André Hellmann, Hermann Wotruba and F. Michael Meyer
Minerals 2019, 9(4), 217; https://doi.org/10.3390/min9040217 - 5 Apr 2019
Cited by 12 | Viewed by 6495
Abstract
Alkaline rocks are worldwide observed as hosts for rare metal (Zr-REE-Nb) minerals. The classification of the ore bearing rock type is challenging due to the fact that textures and mineral assemblage are obscured by post-magmatic alteration. In addition, the alteration causes fine and [...] Read more.
Alkaline rocks are worldwide observed as hosts for rare metal (Zr-REE-Nb) minerals. The classification of the ore bearing rock type is challenging due to the fact that textures and mineral assemblage are obscured by post-magmatic alteration. In addition, the alteration causes fine and intricate intergrowth of the ore minerals with associated gangue. Hence, intensive comminution is necessary to liberate the ore minerals, which is one parameter hampering the economical use of this deposit type. This study provides a quantitative mineralogical investigation of the ore bearing rock suite at Khalzan Buregtei as an example of rare metal deposits. R1-R2 multication parameters are shown to be highly appropriate as quantitative mineralogical indicators based on readily available major element datasets to visualize and quantify alteration types of the ore bearing rock suite. The ore minerals were found to be associated with a cluster-forming assemblage of post-magmatic phases. Automated mineralogy was applied to quantify the textural properties of the ore mineral clusters. This finding permits efficient pre-concentration of rare metal ore at coarser particle size fraction, requiring less energy consuming comminution. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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Review

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24 pages, 8639 KiB  
Review
SEM-Based Automated Mineralogy and Its Application in Geo- and Material Sciences
by Bernhard Schulz, Dirk Sandmann and Sabine Gilbricht
Minerals 2020, 10(11), 1004; https://doi.org/10.3390/min10111004 - 11 Nov 2020
Cited by 90 | Viewed by 16145
Abstract
Scanning electron microscopy based automated mineralogy (SEM-AM) is a combined analytical tool initially designed for the characterisation of ores and mineral processing products. Measurements begin with the collection of backscattered electron (BSE) images and their handling with image analysis software routines. Subsequently, energy [...] Read more.
Scanning electron microscopy based automated mineralogy (SEM-AM) is a combined analytical tool initially designed for the characterisation of ores and mineral processing products. Measurements begin with the collection of backscattered electron (BSE) images and their handling with image analysis software routines. Subsequently, energy dispersive X-ray spectra (EDS) are gained at selected points according to the BSE image adjustments. Classification of the sample EDS spectra against a list of approved reference EDS spectra completes the measurement. Different classification algorithms and four principal SEM-AM measurement routines for point counting modal analysis, particle analysis, sparse phase search and EDS spectral mapping are offered by the relevant software providers. Application of SEM-AM requires a high-quality preparation of samples. Suitable non-evaporating and electron-beam stable epoxy resin mixtures and polishing of relief-free surfaces in particles and materials with very different hardness are the main challenges. As demonstrated by case examples in this contribution, the EDS spectral mapping methods appear to have the most promising potential for novel applications in metamorphic, igneous and sedimentary petrology, ore fingerprinting, ash particle analysis, characterisation of slags, forensic sciences, archaeometry and investigations of stoneware and ceramics. SEM-AM allows the quantification of the sizes, geometries and liberation of particles with different chemical compositions within a bulk sample and without previous phase separations. In addition, a virtual filtering of bulk particle samples by application of numerous filter criteria is possible. For a complete mineral phase identification, X-ray diffraction data should accompany the EDS chemical analysis. Many of the materials which potentially could be characterised by SEM-AM consist of amorphous and glassy phases. In such cases, the generic labelling of reference EDS spectra and their subsequent target component grouping allow SEM-AM for interesting and novel studies on many kinds of solid and particulate matter which are not feasible by other analytical methods. Full article
(This article belongs to the Special Issue Applications of SEM Automated Mineralogy: From Ore Deposits over Processing to Secondary Resource Characterization)
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