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In heavy mineral concentrates of the Elbe, gold and platinum-group minerals (PGMs) are observed. Two fractions (> 63 and < 63 µm) of the concentrate are analyzed by reflected-light microscopy, scanning electron microscopy with automated mineralogy software and electron microprobe analysis (EPMA). Other heavy minerals are cassiterite, ferberite, monazite, uraninite, columbite–tantalite, magnetite, zircon and cinnabar. Scanning electron microscopy determined the modal abundance of PGMs, gold and the other heavy minerals. The PGMs are mainly Os–Ir–Ru–(Pt) alloys, Pt–Fe alloys, sperrylite and rustenburgite. Compositional variation of PGMs and gold was analyzed by EPMA. This showed that Pt–Fe alloys are (1) native platinum (> 80 atom %), (2) ferroan Pt (20 atom % to 50 atom % Fe), (3) isoferroplatinum (2.64 to 3.04 apfu of sum PGE, platinum-group element), (4) tetraferroplatinum group with Ni + Cu + Fe ≈ 50 atom %, and (5) γ(Pt,Fe) with sum PGE > 3.04 apfu. The Os–Ir–Ru–(Pt) alloys show large compositional variations. Platinum and Fe enrichment is typically observed for Ir-rich Os–Ir–Ru alloys. Gold particles often show compositional zoning of Ag-rich cores and Ag-poor rims due to selective leaching of Ag. Similarly, Hg-rich rims of gold particles are analyzed. These are interpreted as the results of in situ amalgamation due to mobilization of Hg from the associated cinnabar particles. The size and shape of the gold particles generally argue for short transportation distances. Similarly, almost euhedral sperrylite and Pt–Fe alloys suggest a source region close to the sampling site. However, roundish Os–Ir–Ru–(Pt) alloys presumably have experienced longer transportation in the river. Gabbroic dikes of the Lusatia block contain sperrylite and gold particles, which can be the source for these particles found in the concentrate. The composition of the Os–Ir–Ru–(Pt) alloys is similar to previous studies on the Vestřev placer in Czech Republic. Both locations are within the drainage area of the Elbe and can therefore be the source of the PGM and gold particles in the concentrate.

CEAS space journal (2022). doi:10.1007/s12567-022-00465-w, Published by Springer, Wien [u.a.]

Metals 8(2), 114 - (2018). doi:10.3390/met8020114, Published by MDPI, Basel

To gain better insight into the composition and recycling opportunities of commercial and industrial (C&I) waste, a sensor-based material flow characterization (SBMC) study was conducted at a C&I waste sorting facility. The 2D and 3D fractions from ballistic separation were monitored so that the material composition of both fractions could be determined. While previous studies and studies in the literature have mainly focus on the SBMC results, this paper will highlight the challenges encountered during the measurement that have a potential impact on the results. The focus in this regard will be on non-NIR related challenges, SBMC preparation challenges, and classification challenges.

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2020; Aachen 1 Online-Ressource (XVIII, 204, c Seiten) : Illustrationen, Diagramme, Karten (2020). = Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2020, Worldwide 120 deposits of critical metals (REE-Nb-Zr) are known which are hosted by alkaline igneous rocks. Some of these deposits were target for academic research and exploration campaigns since the last decades. The high diversity regarding lithologies and textures are two major features of this deposit type. This fact is well-founded by the also complex formation of the rocks which includes multiple stages of magmatic, othomagmatic and post-magmatic hydrothermal processes. As consequence, this complexity is also reflected by post-magmatic ore minerals like zircon, elpidite, bastnaesite and allanite which often features an intricate intergrowth with the gangue. Further, fine to very fine grain size can be observed among the ore minerals. These two typical properties hampering the economic use of this deposit type by a tremendous increase in expenditures regarding exploitation and beneficiation of the ore. In addition, the economical use is impeded by low ore grades (< 1 wt.%) and small total ore volumes. One big advantage of this deposit type, however, is the polymineralic character of the ore causes separation of HREE and LREE into different types of ore minerals which can be separated in mineral processing. Very often an increase in HREE/LREE ratios can be observe due to higher abundance of the more valuable HREE. This fact is often ignored by common deposit assessments using classic values as ore grade and tonnage for evaluation because REE content, for instance, is often reported only as the total sum of the REE. The geometallurgical assessment includes the evaluation of properties like elemental deportment, textures and liberation size of the individual ore minerals and thereby delivers more reliable data for the economic assessment. This study is focused on the Khalzan Buregtei alkali complex situated in western Mongolia as an example for the definition of geometallurgical attributes which can be used for the quantitative description of textural and mineralogical properties of alkaline rocks making them amenable to mineral processing. The outcropping part of the deposit and 3 drill cores were inspected and sampled in detail during two field campaigns. The samples were studies in detail using geochemical, petrographical and image analytical methods like SEM-bases QEMSCAN analysis. The detailed mineralogical investigations were able to identify the post-magmatic processes as key mechanisms for the formation of the ore mineral assemblage found today in the mineralized part of the studied complex. Diversification of mineralogical composition and rock textures observed ongoing to the ore formation were recorded quantitatively and were further evaluated for their use regarding the creation of optimized beneficiation schemes. It was figured out, that fine grained (< 45 µm) ore minerals were concentrated in close association to other secondary minerals like hematite, quartz and fluorite by the post-magmatic processes into pseudomorphic replacements of former magmatic minerals. This preserves magmatic textures as shape as well as the coarser grain size of the magmatic precurser (1000 µm). By this it is possible to distinguish this ore aggregates mineralogically and texturally from the barren rock. For example, separation of ore aggregates could be achieved using the magnetic properties assumed from the associated hematite on coarser grain size level. The quantitative records of these properties are used for forecasting the behaviour of individual ore minerals downstream the processing chain. By this, geometallurgical attributes like mineral association, texture of ore minerals and the elemental deportment are discussed and used for the creation of a beneficiation scheme optimized for the extraction of HFSE bearing ore minerals from alkali granitoid rocks. Further, geometallurgical domains are defined based on elemental deportment data to evaluate the entire deposit. The developed key parameters are finally discussed for their transferability for the geometallurgical assessment of other deposits of the same type. Therefore, fundamental properties of selected deposits were obtained from literature data., Published by Aachen

The global mining industry is facing the challenge of satisfying an increasing demand of primary raw materials, despite decreasing cut-off grades and deposits, which get more and more complex. Strategies for a sustainable and technology-based development of mining methods are demanded globally by societies and policy makers – Germany included. The development and implementation of innovative technologies and processes is an important building block for reaching those requirements. These technologies aim at improving the efficiency of extraction, the transportation, the quality management, the loading/dumping as well as the processing of materials. Regarding the aspects of efficiency improvement and resource optimization, future mining and processing will work increasingly on a (partly-)autonomous basis. The necessary growth of underground exploitation is accompanied by increasing risks and danger. Therefore, the use of innovative technologies shall improve the safety for staff and machinery by minimizing the employees’ exposition to dangerous areas. Due to the devolvement of mining methods and innovative technologies, challenges connected to the transportation and characterization of material flows become more and more important. Up-to-date data of material composition is an enabling technology for an autonomous distribution and a more efficient production. Just in case of this, an optimized processing in downstream plants or a quality dependent dumping is possible. An innovative characterization method of material flows based on the acoustic emission technology is presented within this thesis. With the help of this new technology, the continuous and indirect characterization of material flows becomes possible. This has not been achieved with known methods yet. Besides a description of the current state of research for characterizing mineral resources, the fundamentals of the acoustic emission technology and processes for evaluating material flow are presented. This thesis focusses on the evaluation of machine learning methods for material flow characterization. Feasibility studies were carried out at laboratory scale. These tests included artificial and idealised mass flows, as well as real-world samples. The developed algorithms proved their feasibility in field tests conducted at industrial sites. Based on the gained experience and the requirements collected from industry partners, a concept of a possible inline measurement system, which characterizes material flows in the mineral resources industry, is presented. The thesis finishes with a summary of relevant results and gives an outlook on future areas of application as well as possible aspects of optimization.

Rheinisch-Westfälische Technische Hochschule Aachen, Diss., 2017; 1 Online-Ressource (XII, 168 Seiten) : Illustrationen, Diagramme(2017). = Rheinisch-Westfälische Technische Hochschule Aachen, Diss., 2017, Rare earth elements (REE) are a range of important metals that are used in a variety of hightechnology applications, for instance hybrid cars, smartphones and permanent magnets(Hatch, 2011). They are typically and historically extracted from the conventional mineralsmonazite (REEPO4) and bastnasite (REECO3(F, OH)), which contain considerable amounts ofradioactive elements and have only relatively low concentrations of the more valuable andscarce Heavy Rare Earth Elements (HREE, Gadolinium – Lutetium). These are currentlyalmost exclusively supplied by the Ion Adsorption Clay (IAC) deposits of southern China (Chiand Tian, 2008). Chinas REE monopoly and recently lowered REE export quotas led to anextensive price increase at the market and high uncertainties within the high-tech industryworldwide (Bledsoe, 2012).This thesis deals with the mineralogical, geochemical and geo-hydrometallurgicalinvestigation of an Ion Adsorption Clay occurrence outside China and the development of adigital exploration model for the identification of further exploration targets worldwide. Thework was carried out under the framework of the Siemens research project (S-FB).IAC are formed by hydrolysis-driven lateritic weathering of parental rocks under humidtropical conditions (Kanazawa and Kamitani, 2006). The investigated lateritic samples fromMadagascar derived from alkaline- (foid diorite/gabbro, foid monzonite, foidmonzosyenitewith ~300 ppm REE) and highly REE enriched subalkaline rocks (~11000 ppm). REE bearingminerals in alkaline rocks are restricted to apatite (Ø0.8 wt.% Rare Earth Oxides (REO)) andzircon (Ø0.2 wt.% REO), whereas subalkaline rocks contain bastnäsite (Ø69.3 wt.% REO),monazite (Ø69.7 wt.% REO), fergusonite (Ø43.7 wt.% REO), pyrochlore (Ø17.8 wt.% REO)and zircon (Ø1.6 wt.% REO) as major REE bearing mineral phases. As a result of acidic soilconditions – indicated by a pH < 4 – alumosilicates of the parental rocks (mainly feldspar) arealtered to clay minerals. The IAC samples show a high weathering maturity, due to thealmost complete loss of K, Ca and Na, indicated by a Chemical Index of Alteration (CIA)between 85% and 98%, which is similar to reported values from Chinese IAC deposits (Wu etal., 1990). Consequentially, the samples are mainly consisting of clay minerals (on average>60 wt.%) plus quartz and Fe-oxyhydroxides. They have average REE concentrations of ~500ppm with a maximum of ~1200 ppm and a minimum of ~150 ppm. The material belongs tothe Light Rare Earth Element (LREE, Lanthanum - Europium) IAC type (LREE/HREE = 3.1 –10.1). Statistical calculations show that there is no considerable correlation between the CIAand the total REE (TREE) concentration within the IACs. This signifies that weathering, as aprocess does not lead to a substantial residual REE concentration by itself, but only complieswith the condition of clay mineral formation. On the contrary, the REE enrichment is highlydependent on the parental rocks. The larger the proportion of highly REE enriched parentalrocks, which are involved in weathering, the higher the REE concentration in the weatheringproduct or IAC respectively.Sequential extraction analyses show that the LREE, with Cerium (Ce) as an exception, arepreferentially adsorbed onto clay mineral and Fe-oxyhydroxide surfaces. With increasingatomic number, the REE are progressively in the residual fraction and therefore reside inweathering resistant silicates like zircon. Chinese hydrometallurgical extraction methodsonly recover REE of the exchangeable fraction. Therefore, an alternative leaching processwas developed in this study: By using combined leaching of a H2SO4 and (NH4)2SO4 mixture,REE from the exchangeable and oxide fraction could be extracted leading to an improvedmetal recovery of up to 15% per REE. The excess of impurities/matrix elements (Fe, Al, Si)can be limited by short leaching times.In order to identify potential IAC exploration targets worldwide, a digital exploration modelwas developed with GIS. Locations of especially laterites and soils are considered to indicatesuitable weathering conditions. If these have a spatial relationship, or have been formed inrelatively close proximity to (or from) REE enriched rocks, the weathered material may havea large potential to depict REE enriched IAC. In total, 63 potential IAC exploration targetswere identified worldwide, with promising locations especially in Brazil, contributing to theknowledge enhancement related to the geological availability of REE., Published by Aachen

Rheinisch-Westfälische Technische Hochschule Aachen, Diss., 2017; 187 pp. (2017). = Rheinisch-Westfälische Technische Hochschule Aachen, Diss., 2017, The future availability of Rare Earth Elements (REE) is a very important issue in the 21st century due to a rapid growth in demand Moreover, inequality between supply and demand has led to monopolistic supply conditions controlled by China. This resulted in severe challenges for REE consuming companies and competing REE producers outside China. These circumstances had boosted exploration activities for REE prospects worldwide over the past years. Currently, there are several information sources on REE prospects scattered in scientific literature, company reports, and feasibility studies. However, there is no source accessible which contains all relevant data on REE occurrences and deposits. REE are progressively gaining an essential part within new technologies, such as clean energy, military, and consumer electronics sectors. With each of these sectors incessantly expanding, industrial demand for the constituent REE is rising rapidly, hence their inclusion in the group of strategic elements. An acute problem for strategic elements is the concentration of the world's largest producers in a small number of countries. However, the supply problems are partly based on complex ores, separation issues, and the safe handling of hazardous elements. Further, it depends on the high market volatility and increasing demand. Therefore, the evaluation of REE deposits has become very crucial for sustaining the security of future supply. To analyse future supply options, it is important to point out the difference between producing deposits, a prospective deposit and a simple occurrence.This dissertation analyses current REE prospects concerning geological, mineralogical, economical, mining and environment-technical attributes by creating a DBMS. Another part of this dissertation is the analysis of Critical REE (CREE) and its market structure. These features are essential for analysing the REE sector and its prospects. Moreover, they also help to validate the necessity for developing the DBMS.The main part of developing the DBMS is based on information databases, which contain collective information on 1190 prospects with known REE enrichment. The data are, however, of differing accuracy and reliability, depending on the degree of exploration undertaken to date. Grade and tonnage information is available for about 250 deposits, while more detailed geologic and economic parameters such as material grade, defined resources (TREO tonnage) and reserves, CREE and Basket Price are known for 79 sites. In addition, the database also contains entries pertaining to the abundances of toxic elements such as thorium and uranium. The system includes an economic dataset of REE producing companies and potential producing companies. The evaluation systems implemented in the DBMS are Rating, Clustering, Ranking and Use-Value Analysis. However, all systems evaluate the existing producing deposits as well as the potential deposits for possible future production. Further, the DBMS provides the opportunity to analyse the complete dataset of all prospects by using the implemented rating system. This system includes all occurrences and deposits worldwide and rates them according to attributes of market and statuary mining codes. These attributes, are of high relevance with regard to the assessment of the REE sector. Thus, the evaluation system of Rating is a useful tool to analyse the complete REE sector concerning producing and potential prospects The evaluation system of Clustering is used to subdivide the REE sector by the ore-containing raw mineral, which is relevant for industrial separation and use. Thus, within the evaluation system Clustering, it is possible to constitute different Clustering Groups, namely Eudialyte, Bastnasite and Monazite.The third evaluation system is Ranking, which functions as a pre-evaluation system to the Use-Value Analysis. It is a calculation tool that computes TREO values combined with material grade values of single elements. As a result, it ranks the regarded prospects in TREO per oxide. In this dissertation, three different ranking systems are analysed. Most oxides are weighted equally. However, lanthanum, cerium and samarium are weighted regressively. This is a consequence of the high abundance and thus, lower prices for these oxides. The Use-Value Analysis is the main evaluation system in the DBMS. It evaluates deposits according to selected parameters of the categories Material Grade, Economy and Mining. These parameters include mineral contents, presence of toxic elements, TREO tonnage, Basket Price and production volume. Within the Use-Value Analysis, different case studies according to different views on the REE sector are presented within this dissertation. These case studies evaluate the REE sector concerning its economy, and environmental as well as mineralogical issues., Published by Aachen

In der Erzindustrie findet ein Umdenken statt. Der Einsatz der bewährten aber energieineffizienten Sturzmühlen zur Mittel- und Feinzerkleinerung wird hinterfragt. In der Zementindustrie hat bereits ein vergleichbarer Technologiewandel stattgefunden. In diesem Bereich haben sich vor allem Wälzmühlen auf Grund ihrer Vorteile durchgesetzt. Diese Maschinen stellen auch für die Mahlung von Erzen eine Alternative zu konventionellen Sturzmühlen dar. In der Dissertation werden die Ergebnisse von systematisch durchgeführten Mahlversuchen mit einer Wälzmühle im Pilotmaßstab vorgestellt. Ziel der Untersuchungen mit drei verschiedenen Erzen war es den Einfluss ausgewählter konstruktiver und betrieblicher Parameter auf wichtige Zielgrößen wie Produktfeinheit, Energiebedarf und Verschleiß mit Hilfe von Regressionsmodellen zu quantifizieren und damit die Grundlage für eine Optimierung der Mahlanlage für den neuen Anwendungsbereich zu schaffen.