Kai Bachmann

Kai Bachmann
Helmholtz-Zentrum Dresden-Rossendorf | HZDR · Institute Freiberg for Resource Technology

Geologist/Mineralogist/Geometallurgist, PhD

About

62
Publications
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771
Citations

Publications

Publications (62)
Conference Paper
The current increase in production of lithium-ion batteries claims for the development of technologies for their later recycling. Flotation has been successfully used for recovering spherodized graphite from the black mass of spent batteries. Forecasting flotation outcome from such a complex particle system remains a challenge. Automated mineralogy...
Article
Full-text available
Tailings generated during ore processing may host significant residual contents of valuable commodities, including critical metals. The particle properties of the tailings, such as mineralogy, particle size, and the surface liberation of ore minerals, strongly control processing behaviour. This study explores a novel combination of methods for inco...
Article
Full-text available
Froth flotation predominantly separates particles according to their differences in wettability. However, other particle properties such as size, shape or density significantly influence the separation outcome as well. Froth flotation is most efficient for particles within a size range of about 20-200 µm, but challenges arise for very fine or coars...
Article
Full-text available
Distributional data have recently become increasingly important for understanding processes in the geosciences, thanks to the establishment of cost-efficient analytical instruments capable of measuring properties over large numbers of particles, grains or crystals in a sample. Functional data analysis allows the direct application of multivariate m...
Article
Full-text available
With the increasing demand for metalliferous and mineral raw materials and the consequent depletion of the global natural resource base, the possible utilization of secondary raw material sources is receiving more and more attention. In the present study, we present results from a detailed vanadium deportment study of three basic oxygen furnace sla...
Article
Full-text available
Practically all particle separation processes depend on more than one particulate property. In the case of the industrially important froth flotation separation, these properties concern wettability, composition, size and shape. Therefore, it is useful to analyze different particle descriptors when studying the influence of particle wettability and...
Article
Full-text available
Discordant iron-rich ultramafic pegmatites (IRUPs) intersect the UG2 chromitite at many places in the Bushveld Complex. The effects of IRUP interactions on the UG2 ore mineralogy and PGE grade are assessed at the Thaba mine, north-west Bushveld, based on a borehole profile through the UG2 layer and detailed analysis of mineral textures and composit...
Article
Full-text available
In this study, synthetic pure cassiterite and cassiterite doped with two different Fe contents were successfully recrystallized by means of sintering. Their crystal structure and chemical compositions were characterized by X-ray powder diffraction (XRD) as well as scanning electron microscopy (SEM) combined with energy-dispersive X-ray (EDX) analys...
Preprint
Full-text available
Computed tomography (CT) can capture volumes large enough to measure a statistically meaningful number of micron-sized particles with a sufficiently good resolution to allow for the analysis of individual particles. However, the development of methods to efficiently investigate such image data and interpretably model the observed particle features...
Article
Full-text available
Recycling is a potential solution to narrow the gap between the supply and demand of raw materials for lithium-ion batteries (LIBs). However, the efficient separation of the active components and their recovery from battery waste remains a challenge. This paper evaluates the influence of three potential routes for the liberation of LIB components (...
Presentation
Full-text available
Recycling symposium This talk presents how we can separate the fine active particles (lithium metal oxides and graphite) from the black mass by using froth flotation. This research demonstrates that graphite can be recovered from spent lithium ion batteries and recycled into new anodes
Article
The exploitation of mine waste materials as secondary resources requires in-depth mineralogical analyses, with metal deportment being of particular relevance for metal recovery. Using a combination of the Scanning Electron Microscope (SEM)-based Mineral Liberation Analyser (MLA) and Electron Probe Micro-Analyser (EPMA) methods, the deportment of le...
Article
Full-text available
We use mineral liberation analysis (MLA) to quantify the spatial association of 15,118 grains of accessory apatite, monazite, xenotime, and zircon with essential biotite, and clustered with themselves, in a peraluminous biotite granodiorite from the South Mountain Batholith in Nova Scotia (Canada). A random distribution of accessory minerals demand...
Article
Full-text available
Mechanical recycling processes aim to separate particles based on their physical properties, such as size, shape and density, and physico-chemical surface properties, such as wettability. Secondary materials, including electronic waste, are highly complex and heterogeneous, which complicates recycling processes. In order to improve recycling effici...
Article
Full-text available
The second law of thermodynamics, through exergy analysis, is commonly applied to quantify process inefficiencies in metallurgical reactors, however, it has not yet been used to understand physical processes and changes in particle-based systems. Correlating the state of mixing of particle texture and homogeneous liquid mixtures is of importance. T...
Thesis
Full-text available
The modern mining industry faces a number of important technical challenges, such as declining ore grades, complex mineral associations, fine-grain size and increasing geological variability. To meet these challenges geometallurgical models are constructed to quantita-tively predict how ores will behave during extraction and beneficiation. Current...
Article
Through a series of in-house routines of R, an open-source programming language for statistical computing, statistical analysis is applied to automated process mineralogy data to describe the performance of an industrial scheelite rougher flotation bank. These routines allow 1) freeing the user from the limitations of the menu-driven built-in proce...
Article
Full-text available
Many by-product metals are classified as critical. However, they are only of marginal interest to many mining companies and are rarely part of detailed resource statements or geometallurgical assessments. As a result, there is a general lack of reliable quantitative data on the mineralogy and spatial distribution of these metals in ore deposits – h...
Conference Paper
Full-text available
All major sources of economically important platinum-group elements (PGE) are associated with sulfides and chromite in mafic-ultramafic rocks. The Bushveld Complex in South Africa is the largest PGE deposit worldwide. Chromitites of the Lower Group (LG) and Middle Group (MG) of the Bushveld Complex hold PGE contents of a few ppm. However, these chr...
Article
Full-text available
In this paper, prediction models are proposed which allow the mineralogical characterization of particle systems observed by X-ray micro tomography (XMT). The models are calibrated using 2D image data obtained by a combination of scanning electron microscopy and energy dispersive X-ray spectroscopy in a planar cross-section of the XMT data. To reli...
Article
The Lower and Middle Group chromitites of the Bushveld Igneous Complex in South Africa are the source of a very large portion of the global chrome supply. The recovery of platinum group elements and base metals (Ni, Cu) as by-products has the potential to add value to these chrome resources. Yet, the effectiveness of chromite and platinum-group ele...
Article
The Bushveld Complex, the largest layered mafic-ultramafic intrusion worldwide, is host of numerous, laterally continuous and chemically similar chromitite layers. Based on their stratigraphic position the layers are subdivided into a lower, middle and upper group (LG, MG and UG). Within these groups the layers are numbered successively – from the...
Article
Full-text available
The Lower Group chromitites of the Bushveld Igneous Complex are mined for chromite as a primary product. The recovery of platinum group elements and base metals (Ni, Cu) as by-products has the potential to add value to the chromite resources. This study focuses on the LG-6 and LG-6A chromitite seams at the Thaba mine located on the western limb of...
Article
In this paper, three-dimensional (3D) image data of ore particle systems is investigated. By combining X-ray microtomography with scanning electron microscope (SEM)-based image analysis, additional information about the mineralogical composition from certain planar sections can be gained. For the analysis of tomographic images of particle systems t...
Article
The tennantite-tetrahedrite solid-solution series [called fahlore; (Cu,Ag)6Cu4(Fe,Zn,Cu,Hg,Cd)2(Sb,As,Bi,Te)4(S,Se)13] is widespread in many geological environments. Since it incorporates heavy metals and toxic elements, a better understanding of its weathering behaviour and details of its weathering process is important to evaluate environmental r...
Presentation
Full-text available
This contribution introduces a 3D geometallurgical model that has been developed to assess the resource potential of PGE (+Ni and Cu) recovery at the Thaba chromite mine, South Africa. The Thaba Mine is located on the northwestern limb of the Bushveld Complex and is operated by Cronimet SA. The geometallurgical model is based on a structural model...
Preprint
In this paper, 3D image data of ore particle systems is investigated. By combining X-ray micro tomography (XMT) with scanning electron microscope (SEM) based image analysis additional information about the mineralogical composition from certain planar sections can be gained. For the analysis of tomographic images of particle systems the extraction...
Article
The identification and accurate characterization of discrete grains of rare minerals in sulfide base-metal ores is usually a cumbersome procedure due to the small grain sizes (typically <10 μm) and complex mineral assemblages in the material. In this article, a new strategy for finding and identifying indium minerals, and quantifying their composit...
Article
Full-text available
The polymetallic Cu–Zn ore of the Rockliden massive sulphide deposit in the Skellefte District in north-central Sweden contains a number of deleterious elements in relevant concentrations. Of particular concern is the amount of antimony (Sb) reporting to the Cu–Pb concentrate. The aim of this study was to compare different model options to simulate...
Conference Paper
Full-text available
Minerals can be liberated by random fracture of particles into smaller fragments or by detachment along phase boundaries. These two mechanisms represent borderline cases. When ores get comminuted the liberation of minerals is achieved to some extent by both mechanisms. This article describes a method to determine the extent of transgranular and int...
Article
Minerals can be liberated by random fracture of particles into smaller fragments or by detachment along phase boundaries. These two mechanisms represent borderline cases. When ores get comminuted the liberation of minerals is achieved to some extent by both mechanisms. This article describes a method to determine the extent of transgranular and int...
Conference Paper
Full-text available
The Kupferschiefer is one of the most important sources of copper and silver in Europe, with resources located mainly in Poland and Germany. Mineralization is stratabound and hosted by sedimentary rocks comprising of sandstone, black shale, and carbonate rocks. Because Kupferschiefer-type ores are typically complex and very fine-grained, alternativ...
Conference Paper
The Kupferschiefer is one of the most important sources of copper and silver in Europe, with resources located mainly in Poland and Germany. Mineralization is stratabound and hosted by sedimentary rocks comprising of sandstone, black shale, and carbonate rocks. Because Kupferschiefer-type ores are typically complex and very fine-grained, alternativ...
Conference Paper
Full-text available
The article describes a method for the evaluation of the upgradeability of a material based on the mineralogical limiting curve (liberation) and the performance of the separator used for concentration (separation). The characteristic curves of both process steps are plotted together in a FUERSTENAU upgrading diagram evaluating the recovery of valua...
Article
Full-text available
The European Kupferschiefer deposits offer potential for regional resources of base metals such as copper. Because of its chemical and mineralogical complexity the Kupferschiefer ore is still investigated regarding sustainable exploiting strategies such as (bio)leaching with organic acids. The current study examines different processing parameters...
Conference Paper
Full-text available
The world-class volcanogenic massive sulphide deposit of Neves-Corvo, Portugal, is one of the largest and richest in the Iberian Pyrite Belt (IPB) [1]. Besides its size, other notable features include its high tin and indium content [2]. Mean concentrations of 30 – 50 ppm indium in whole ore make it an attractive source of this rare high-tech metal...
Conference Paper
Full-text available
Automated mineralogy has become a standard method to quantify rock properties such as modal mineralogy and grain liberation in mining industry. As this method uses only little amounts of sample material, it is crucial that sample preparation guarantees representativity. The presented study evaluates this representativity for the last step of sample...
Conference Paper
Full-text available
Studies of the mineralogical deportment of indium generally focus on the measurement of trace concentrations in major ore minerals. The importance of actual In-minerals such as indite, roquesite and sakuraiite is not usually assessed. This is due to their low abundance and optical similarity to other, more common, sulphide minerals (e.g. sphalerite...
Article
Identification and accurate characterization of platinum-group minerals (PGMs) is usually a very cumbersome procedure due to their small grain size (typically below 10 µ m) and inconspicuous appearance under reflected light. A novel strategy for finding PGMs and quantifying their composition was developed. It combines a mineral liberation analyzer...
Article
Full-text available
The Rockliden massive sulphide Zn–Cu deposit contains minor amounts of Sb minerals. The Sb mineralogy is complex in terms of composition, micro textures and mineral associations. The main Sb minerals comprise tetrahedrite, bournonite, gudmundite and Sb–Pb sulphides such as meneghinite. The presence of these minerals is especially critical to the qu...
Article
Full-text available
A method is presented for the evaluation of mineral processing by liberation and upgrading. The method bases on the plot of recovery of valuables versus the recovery of gangue (Fuerstenau upgrading curve). The locking curve of a feed material was plotted together with the upgrading curve in a Fuerstenau diagram. The assessment of liberation and upg...
Conference Paper
Full-text available
Kristineberg is the largest mine and VHMS deposit in the Palaeoproterozoic Skellefte District, Sweden. The deposit was discovered in 1918, and it has been mined since 1941. Besides the Kristineberg deposit, several other VHMS deposits have been mined in the Kristineberg area. Despite the long history of mining, significant advances are still being...

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