Andreas Kamradt's research while affiliated with Martin Luther University Halle-Wittenberg and other places

Publications (15)

Article
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Mining and mineral processing industry are under pressure from political and social stakeholders to deliver products more sustainably with a much smaller environmental impact. Technical innovations to achieve these goals include reduction in energy consumption, waterless mineral processing, coarse particle liberation, and safe dry stacking of taili...
Book
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The Storkwitz-Carbonatite is a Late Cretaceous intrusive complex, which is well-explored by a relatively large number of exploration bore holes both from the 1970ies, 1980ies and from one more recent bore hole, SES-1/2012. The carbonatite complex hosts a (cur-rently) marginally economic mineralisation of rare earth elements (REE) and niobium, which...
Conference Paper
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Advanced tropical weathering of alkaline-carbonatite rock led to the accumulation of increased amounts of economically important minerals and elements-such as apatite, anatase, and rare earth elements within the supergene profile from the Catalão Region, Brazil. Whole rock geochemical analyses reveal a vertical zonation of the phosphate ore, trendi...
Conference Paper
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The Carnon River Mining District, part of the Cornubian Ore Field in SW-England, hosts polymetallic and multi-phase tin and base metal vein mineralisation in the cupolae of Variscian granites. Geologically, the study area is composed of Devonian clastic metasedimentary rocks with intercalations of amphibolite, intruded by Late Variscian granites. M...
Conference Paper
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The Hashim Abad magnetite-skarn occurrence is situated in the Urumieh-Dokthar-Magmatic-Arc, Central Iran. It is located in a transition zone of cretaceous, dolomitic limestone and a miocene, dioritic intrusion along a NW-SE striking fault. A contact metamorphic influence of the wall rock is marked by the formation of green amphiboles in the magmati...
Poster
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The Hashim Abad magnetite-skarn occurrence is situated in the Urumieh-Dokthar-Magmatic -Arc, Central Iran. It is located in a transition zone of cretaceous, dolomitic limestone and a miocene, dioritic intrusion along a NW-SE striking fault. A contact metamorphic influence of the wall rock is marked by the formation of green amphiboles in the magmat...
Article
The extraction of copper from black shales associated with fine-grained and complex base metal ore mineralization traditionally using pyrometallurgy becomes increasingly uneconomic, because one of the most significant cost factors is the high energy consumption. Thus, energy-saving alternative mineral processing methods are to be considered to impr...
Article
In this study, two black shale copper ores from different Mid-European Kupferschiefer-type deposits and their flotation concentrates were used for bioleaching tests. All samples were subjected to stirred tank bioleaching using an acidophilic, moderately thermophilic microbial consortium. The distribution of sulfides and gangue minerals in the ores,...
Article
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The comminution of commodity particles such as ore minerals in mining and metals from recycling of slags, armored concrete, and incinerator slags by crushing, grinding, and milling makes up the biggest single cost factor in mineral processing. The comminution of graphite in various innovative applications is a particular challenge to the mineral pr...
Chapter
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The comminution of commodity particles such as ore minerals in mining and metals from recycling of slags, armoured concrete, and incinerator slags by crushing, grinding, and milling makes up the biggest single cost factor in mineral processing. In spite of a marked lack in the development of new and significantly more efficient comminution equipmen...
Article
Full-text available
The new VeRo Liberator® has been recently developed by PMS, Hamburg, Germany, and represents a highly efficient impact crushing system for dry comminution of ore, slag, armoured concrete, and aggregate in the 100 t per hour throughput class. The VeRo Liberator® operates with a vertical axle-in-axle system, which is equipped with a total of up to 14...
Article
Full-text available
Dumps in the Central German Mansfeld mining district have been investigated by a multi-disciplinary research team to develop a holistic concept for the recovery of base and trace metals from low-grade Kupferschiefer ore. Geochemical and mineralogical data from representative sampling indicate that the low-grade Kupferschiefer dumps contain signific...

Citations

... Some of these elements occur in obscure valences, such as Sb and Tl (Wei et al., 2018). Other elements such as Sn, As, Pb and Bi often exist in sphalerite in the form of small mineral inclusions (Ye et al., 2011;Meyer et al., 2019;Xu et al., 2020;Xing et al., 2021). ...
... It was reported that when copper sulfide ores (containing bornite, chalcopyrite and pyrite) are bioleached with A. ferrooxidans, pyrite and chalcopyrite were more recalcitrant to acid leaching and bacterial oxidation compared with bornite (Bevilaqua et al., 2010). Another example was that after bioleaching of a flotation concentrate which contained bornite (20.6%), chalcopyrite (10.7%), galena (8.6%), sphalerite (3.2%), chalcocite (1.7%), and pyrite (7.9%), bornite and chalcocite barely remained in the residues, while chalcopyrite and pyrite were hardly dissolved (Kamradt et al., 2018). Though the rest potential of the sulfides is an important factor in their dissolution behaviors in most cases, it should be noticed that the kinetics of anodic dissolution of each sulfide and the reduction of ferric ion on each sulfide need to be taken into consideration when two sulfide minerals in contact are leached by an oxidant (such as ferric iron). ...
... However, the machine works not only in a dry process but is additionally capable of actively warming/heating and thus drying the comminuted material by converting the impact energy into thermal energy. Another effect of the high velocity of the impacts is the embrittlement of viscous ("ductile") particles, such as spherical metallic copper droplets in smelter slags that remain spherical and are not flattened as in conventional comminution systems ( Fig. 13 in [4]). Technically, the equipment is easy to maintain since the housing can be lifted hydraulically for single-tool replacement or the entire drive shaft and tool unit can be pulled from the main frame. ...
... This, however, comes at great energy expense, since particles have to be ground to sizes below 100 µm to achieve meaningful liberation. Unfortunately, the larger amount of energy applied to the comminution process does not contribute to particle breakage, but is rather wasted on processes such as driving the mechanical parts of the equipment, heat, and sound energy [1]. Comminution comprises crushing and grinding, but the former has been proven to be 10 to 20 times more energyefficient than the later [2]. ...
... The operational ore breakage dynamics in AG/SAG mill during milling at a given mill speed is predominant by impact alongside abrasion, attrition, and nipping (Lynch, 2015;Takalimane, 2014). Among the upstream and downstream extraction processes, comminution circuit including AG/SAG mill is known to be the most energy-intensive operation (Ballantyne, Powell and Tiang, 2012;Borg, Scharfe and Kamradt, 2016). The mill performance efficiency is significantly affected by multiple processing parameters such a mill speed, feed variability, ball loading, pulp density, water flow rate, mill lifter heights and profile/configuration (Das et al, 2011;Nayak et al, 2020;Royston, 2007;Uys, 2018). ...
... Accompanying scientific research on the characterisation of feeds and products continued but was extended to research, trying to understand the functional principle of the VeRo Liberator® that delivers such innovative and drastically more efficient unintended comminution results. The university research team was enlarged by including the rock mechanics group, to test the initially proposed comminution mechanism (Borg et al. 2015a) and to refine it to our current understanding (Borg et al. 2015b(Borg et al. , 2015c(Borg et al. , 2016. Market entry has been achieved in late 2016, when Anglo American, after a series of comminution tests on different ores, ordered a bespoke VeRo Liberator®, specially designed to be used in a large-scale pilot test at one of their operations. ...
... As sources of information, scientific papers, various reports by private companies, and geological exploration reports as well as patents have been reviewed for current work. When reviewing black-shaleassociated sulfide ores such as Kupferschiefer, we have paid attention to the true black shale fraction (major mineralization occurs in sandstones and other rocks) or tailings that are being increasingly considered as potential raw materials (Chmielewski et al., 2009;Kamradt et al., 2012). Process flowsheets were drawn with HSC Chemistry -Sim 10 software (Roine, 2021). ...
... So far, the focus of Life Cycle Assessment (LCA) studies has been mainly on smelting and refining (Segura-Salazar et al. 2019). However, nowadays, as far as the demand is increasing and the supply is moving to lower grade deposits (Kutschke et al. 2015), the role of mining and beneficiation (the latter also known as mineral processing or ore dressing) is expected to become more and more relevant in terms of energy demand and environmental issues (Mudd and Jowitt 2018). Some studies have shown that mining and beneficiation can account for a significant contribution to the environmental impacts of the life cycle of metals (Davidson et al. 2016;Nuss and Eckelman 2014). ...