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Aufbereitungstechnik : AT 42(5), 243-250(2001)., Published by Bauverl. BV, Gütersloh

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.

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.

Die Analyse des wissenschaftlich-technischen Standes zeigt, dass die gegenwärtige mineralogisch-petrographische Gesteinscharakterisierung in vielen Fällen nur eine verbale Gefügebeschreibung erlaubt. In der Aufbereitungstechnik ist diese Verfahrensweise jedoch nicht ausreichend. Hier ist eine quantitative Charakterisierung der Gesteine erforderlich. Deshalb bestand die Aufgabe darin, eine neue mathematisch-petrographische Methode zur Charakterisierung der unterschiedlichen Gesteinseigenschaften zu entwickeln. Im Ergebnis der neuen mathematisch-petrographischen Methode wurde festgestellt, dass die verbale Beschreibung der Gesteinsstruktur und -textur durch quantitative Gesteinskennwerte ersetzt werden kann. Mit Hilfe der quantitativen Gesteinskennwerte kann eine Prognostizierung relevanter Produkt- bzw. Systemkenngrößen ohne zerkleinerungstechnische Untersuchungen vorgenommen werden. Die Gesteinskenngrößen erlauben eine Einschätzung des Gesteins hinsichtlich Brechbarkeit und Produktkornform einerseits sowie Verschleiß und erforderlichem Energieaufwand andererseits und stellen somit eine wichtige Grundlage für die Auswahl und den Betrieb der Maschinen und Anlagen der Naturstein-Industrie dar.