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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 intergranular fracture based on 2-dimensional analysis of surface exposure of minerals. The approach uses the unbiased surface information like of phase specific surface area (PSSA), phase specific free surface (PSFS) and phase specific locked surface (PSLS) of minerals and their change with comminution. The parameters are discussed related to the normalized grain size, which is the ratio of mineral grain size in the product to mineral grain size in the unbroken material. Finally, the amount of transgranular and intergranular fracture on surface exposure can be calculated using the phase specific surface parameters. A sedimentary rock (apatite ore), an igneous rock (nepheline-syenite) and an artificial material (copper slags) were ground to different fineness. Based on the mineral liberation analysis (MLA) of feed and products, the extent of phase boundary fracture on the surface exposure of the minerals is studied.

SEM-based image analysis (aka Automated Mineralogy) has become a standard method not only in mineral processing but also for petrological studies, e.g., for the determination of modal mineralogy, search for rare phases, or for fabric parameters such as grain size and mineral association. A very small aliquot (the surface of a polished epoxy block prepared from a few grams of ground material or the surface of a polished thin section) are used during analysis. All caution is needed to assure that this small aliquot is representative of the sample material to be examined – and that it yields the information of particular interest, e.g., the abundance and microfabric relations of rare phases such as PGEs or Au. SEM-based image analysis is performed on surfaces, i.e. observations are obtained on two-dimensional surfaces, whereas the relevant attributes all related to the properties of three dimensional mineral grains/particles/rock volumes. For grain mounts, the appearance of a grain on the analyzed surface is controlled by the behavior of the grain during sample preparation and depends on grain size, shape and density of phases. Cutting effects usually cause an underestimation of grain size for isotropic grains, whereas phases forming grains with a shape preferred orientation (e.g. mica) may be over- or underestimated depending on the plane chosen for analysis. This causes also bias in modal mineralogy, grain size and shape or mineral association and liberation. At best, measurements can be precise but not accurate with reference to the entire sample. To evaluate these effects, a systematic study was performed on grain mounts of a mineralogically rather simple greisen from the Erzgebirge (Germany), mainly constituted by zinnwaldite mica, topaz and quartz, i.e minerals with different density, mineral grain size and shape. Eight values of the ratio solid load/resin and analyses of two cutting planes (xy and xz) were performed, having 16 MLA measurements. Apparent modal mineralogy compositions were statistically compared, using bootstrapping techniques to estimate their uncertainty. Results showed a significant and constant difference of the topaz proportion between xy and xz measurements, as well as a significant systematic reduction in the ratio zinnwaldite/quartz with increasing solid load/resin ratio on xy measurements, a bias absent from xz measurements. In conclusion, sample preparation biases can be reduced by measuring on transverse planes (xz) or reducing the amount of resin added to the sample. For a first time the error in analyzing modal mineralogy was quantified. Other biases remain, like e.g. stereological distortion in estimating 3D quantities from 2D measurements. Such challenges are left for further research.

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, alternative approaches for metal recovery, such as bioleaching, are becoming an attractive alternative to flotation. The focus of this study was a detailed monitoring of mineralogical changes through time during bioleaching of sandstone-hosted Cu-mineralization from two Polish Cu-mines. The change of modal mineralogy, mineral associations, microbial activity and copper recovery of a copper bearing sandstone during bioleaching with Acidithiobacillus ferrooxidans DSM 14882 was investigated. A series of 18 batch cultures and 18 abiotic controls in shaking flasks with a solid content of 6 wt.% was prepared and sampled every 3 to 4 days over a period of 18 days. Mineralogical analysis of leaching residues was done by mineral liberation analysis (MLA) and X-Ray powder diffraction (XRD), while chemical analysis of dissolved copper and ferric/ferrous iron was carried out with ion chromatography (IC). The investigated sandstone ore contained 2.5 wt.% copper, mainly bound to the copper minerals chalcocite (Cu2S, 1.3 wt.%), covellite (CuS, 1.0 wt.%) and bornite (Cu5FeS4, 0.9 wt.%). After 18 days the copper extraction was 84% for biotic samples and therefore significantly higher compared to abiotic controls (52%). MLA data showed that biotic dissolution was faster for all three copper ore minerals. The results of detailed mineralogical analysis indicate a passivation by jarosite during the leaching process, especially caused by ammoniojarosite. It was possible to trace progressive changes of each copper sulphide over the entire bioleaching process and calculate dissolution/formation rates by means of MLA data.

An acute anteroseptal infarction was diagnosed in a 51-year-old man whose ECG showed ST elevations in leads V1-V4 after acute retrosternal pain for about 20 min. Angiography revealed proximal occlusion of the right coronary artery, while the dominant left coronary artery was fully patent. After successful recanalization of the right coronary artery with intracoronary infusion of urokinase, the ST elevations quickly disappeared and impending right-heart infarction was avoided. Isolated right-heart infarction can imitate the ECG pattern of anteroseptal infarct and should be considered if the height of ST elevations diminishes from V1 to V4.

Echocardiography on a 29-year-old woman with exercise-unrelated tightness in the left chest for some months demonstrated an echo-dense space-occupying lesion in the outflow tract of the right ventricle (RV). Nuclear magnetic imaging revealed an ovular, fat-containing tumour, 3 x 2 x 2 cm in size. Because of threatened obstruction of the RV outflow tract removal of the tumour under cardiopulmonary bypass was undertaken. But complete removal was possible only by resecting a 2 x 3 cm area of the anterior wall of the RV, the resulting defect being covered with a Goretex patch. Histological examination identified the tumour as a rhabdomyolipoma. The patient was free of symptoms 1 year postoperatively.

Polymetallic Cu-Ag ores of the Central European Kupferschiefer deposits are one of the most important sources of Cu in Europe. Because the ores are typically complex and often exceptionally fine-grained the development of efficient alternatives to conventional beneficiation strategies are an important target of current research. Biomining – the use of biological components for metal extraction - may offer solutions that are both efficient and environmentally benign. As conventional bioleaching with acidophilic microorganisms is impeded by the high carbonate content of the Kupferschiefer ores, heterotrophic microorganisms and glutamic acid are investigated as a possible alternative in the present study. The focus of this investigation is solely on the recovery of copper from the Kupferschiefer sensu strictu. Bioleaching experiments were carried out using such material from the Polkowice Mine in Poland. This material is marked by high grade (3.8 wt% Cu), complex ore mineralogy (chalcocite, bornite, chalcopyrite and covellite in significant quantity) and a gangue mineralogy that is rich in carbonate, organic carbon and clay minerals that together form a very fine-grained matrix. (Bio)-leaching experiments yield best results when glutamic acid alone is used – reaching Cu recoveries up to 44 %. Recoveries are consistently lower in experiments in which glutamic acids and microbiological metabolites are both present. The leaching of chalcocite renders the greatest contribution to the Cu recovered to the leach solution in all experiments. It can be concluded that glutamic acid solubilise copper efficiently from Kupferschiefer, mainly from chalcocite.

Anhand des Beispiels von Indium wird gezeigt wie geometallurgische Denkweisen und Methoden auf typische Beiprodukte angewendet werden können. Besonders für Elemente wie Gallium, Germanium, Selen und Tellur fehlen bisher leider ähnliche Arbeiten völlig. Es wäre daher wünschenswert, dass solche an ausgewählten Lagerstätten durchgeführt werden. Auch für typische Strafelemente wie Cadmium oder Arsen könnte dies sinnvoll sein. Allerdings würde der Fokus bei letzteren eher auf der Vermeidung ihrer Anreicherung in den Konzentraten liegen. Die hier vorgestellte Arbeit könnte für solche Studien als Muster dienen.

The Areachap Terrane represents the medium- to high-grade metamorphic and deformed remnants of a Mesoproterozoic (ca. 1.24–1.30 Ga) volcanic arc bound to the margin of the Archean Kaapvaal Craton in the east, and the polydeformed and metamorphosed Proterozoic Namaqua Province in the west. There has been protracted debate as to the exact nature, origin, age and tectonic evolution of this terrane, adjacent to an important Mesoproterozoic crustal suture between the Archean Kaapvaal Craton and the Namaqua Province, which developed during the ~1200-1000 Ma Namaquan Orogeny. The Areachap Terrane comprises highly deformed bimodal volcanic and volcano sedimentary successions that host a number of massive sulphide base metal orebodies. Samples from three of these orebodies at different locations were analysed to determine the age and P-T conditions of metamorphism along the Areachap Terrane. Metamorphic ages were determined by electron microprobe chemical dating of monazite. Garnet- and amphibole-bearing mineral assemblages were used for geothermobarometry. At the Areachap Mine, located in the northern sector of the Areachap Terrane, monazite geochronology yields evidence for two populations of Th-U-Pb-ages at 1432±30 Ma – a possible protolith age – and a metamorphic age of 1153±21 Ma. Kantienpan and Copperton, representing the central and southern sector of the Areachap Terrane respectively, yield monazite ages for a younger metamorphic event with U-Th-Pb-ages of 1108±19 Ma and 1104±17 Ma, respectively. Geothermobarometric data give a differentiated view on the metamorphic evolution of the Areachap Terrane. An arc consistent clockwise P-T evolution path and upper amphibolite-facies peak metamorphic conditions are consistent at the three locations. The Areachap site shows a short prograde development with 9.0 kbar maximum pressure at circa 700°C maximum temperature and a subsequent retrograde metamorphism. At Kantienpan, on the other hand, maximum metamorphic conditions of 6.5 kbar at 600 - 650°C are obtained, whereas at Copperton retrograde metamorphism is most distinct with maximum pressures around 8 kbar at circa 650°C. These locally differentiated metamorphic and geochronological evolution paths in the Areachap Terrane are closely related to the Mesoproterozoic events in the adjacent Namaqua Province.

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) rendering the reliable assessment of their concentration by traditional methods (point-counting) difficult at best. Their low abundance also means that reference materials for many of the relevant minerals are not readily available. This contribution presents a general method developed to overcome these problems with SEM-based automated mineralogy. Using five carefully selected ore samples from the Neves-Corvo deposit it is shown that this approach not only allows for the reliable identification of trace indium minerals (roquesite) present within the ores, but it also enables the quantification of their respective concentrations and thus their contribution to the overall indium budget. Furthermore, additional information on other geologically and/or technologically relevant parameters like mineral association, grain shape and grain size are readily available.

Identification and accurate characterisation of platinum group minerals (PGM) is a very cumbersome procedure due to their grain sizes that are mostly below 10 µm and a light microscopic appearance that is rather inconspicuous. A novel strategy for finding PGM and quantifying their composition was applied by combining a mineral liberation analyser (MLA), a point logging system and an electron probe microanalyser (EPMA). As a first step the PGM are identified, using the MLA. Grains identified as PGM are then marked and coordinates recorded and transferred to the EPMA. Case studies illustrate that the combination of MLA, point logger and EPMA results in the identification of several times more PGMs than by careful reflected light microscopy. Wavelength dispersive spectrometer analyses of PGM by EPMA require considerable caution due to overlaps of X-rays on both peak and background of almost all PGE and associated elements. X-ray lines suitable for quantitative analyses need to be carefully selected. As peak overlaps cannot be avoided completely, an offline overlap correction based on weight percent proportions has been developed and explained in detail. Results obtained with the procedure proposed in this study attain acceptable totals and atomic proportions, concluding that the applied corrections are appropriate.

In the last 20 years the development of new analytical methods and devices provided the possibility of high-resolution data in almost every field of science. Information is much easier to retrieve and in a depth never known before. But often these methods are expensive and a lot of time is needed for proper data acquisition and analysis. For example, in geosciences the Mineral Liberation Analyser (MLA) provides quantitative mineralogical microstructural information. This is a scanning electron microscope with automated software for high resolution images of rock specimen and sample compounds from mineral processing. The information can be used for evaluating the effect of mineral processing on a given ore sample in order to find the optimal processing parameters of each step and predict the overall recovery and grade the requested value minerals. For example, the magnetic susceptibility of a mineral phase determines its behaviour during magnetic separation. It can be modelled as a linear combination of the susceptibilities of each occurring mineral phase with respect to its mass fraction: \begin{equation} \label{equ} \overline{\chi_s} = \sum_{i=1}^{n} \frac{m_i}{m_s}\chi_i. \end{equation} (chi_s: susceptibility of the whole sample, chi_i: susceptibility of the i-th mineral phase, m_s: mass of the whole sample, m_i mass of the i-th mineral phase) Unfortunately, quite often only the susceptibility of the composition can be measured in an experiment due to several reasons, e.g. if the composition consists of too many distinct components and the contained mineral particles consist of several mineral phases. During the separation the sample is split into several classes. The susceptibility can only be measured for such a class. But we would like to infer the susceptibility for every single mineral phase. The common approach is a linear model, which fails if we have more mineral phases than susceptibility classes found in the experiment. Our approach uses bootstrapping for constructing new subsamples out of the measured ones. Since every particle has the given mean property, taking such subsamples is like repeating the experiment. This provides a broader base with subsamples having a much higher variability of phase compositions. We repeat this procedure for every susceptibility class. Furthermore we often do not only have one single value for each class found in the experiment, but a set of them within a certain bounded range. Instead of using the average we arbitrarily assign one of them to each new sample. This additionally prevents us from too many linear dependent equations using (\ref{equ}). We end up in an over-determined system of linear equations. For the solution we use the Moore-Penrose inverse, giving us the possibility to compute an estimation error for every mineral phase relying on the corresponding eigenvalue. We will discuss simulation results and apply the method to actual experimental data.

The identification and accurate characterisation of platinum-group minerals (PGMs) is usually a very cumbersome procedure due to their small grain size (typically below 10 µm) and inconspicuous appearance under reflected light. A novel strategy for finding PGMs and quantifying their composition was developed. It combines SEM-based automated mineralogy, in this study mineral liberation analyser (MLA) Quanta 650F by FEI, a point logging system (JEOL) and a FE-EPMA (JEOL JXA-8530F). Thin sections from a layered intrusion (UG2) in the Bushveld Complex and from two Uralian-Alaskan-type complexes in the Ural Mountains, Russia, were investigated as case studies. As a first step, the PGMs are identified using the MLA. Grains identified as PGMs are then marked and coordinates recorded and transferred to the EPMA. Case studies illustrate that by introducing MLA for the efficient and largely automated identification of PGM grains in polished thin sections, up to 20 times more PGM grains were identified, whilst shortening time needed and avoiding the effects of human error invariably associated with reflected light microscopy. This is mainly due to the facts that (a) PGM with grain sizes < 5µm are reliably identified and (b) PGM and closely associated base metal sulfides and sulfosalts are well differentiated with the MLA. The analysis of PGMs by EPMA requires considerable effort due to the often significant overlaps between the X-ray spectra of almost all platinum-group and associated elements (e.g. OsMβ on IrMα and AuMβ on HgMα). X-ray lines suitable for quantitative analysis need to be carefully selected. As peak overlaps cannot be avoided completely, an offline overlap correction based on weight proportions has been developed. Considerable variations in the repeatedly determined overlap factors illustrate the need for a re-determination of the overlap factors with each calibration. Results obtained with the procedure proposed in this study attain acceptable totals and atomic proportions, indicating that the applied corrections are appropriate.

Secondary raw materials are becoming increasingly more important in ensuring the stability of critical metal supply. Ashes, slags, dusts and other industrial residues are produced in large quantities. Precise and accurate chemical and mineralogical data, knowledge of distribution of valuable and deleterious elements in the single phases as well as information about homogeneity and grain size distribution of the minerals are crucial for the development of new extraction technologies. Gaining these essential information can be achieved by using SEM-based automated mineralogical analysis. However, the large particle size range, the dominance of very small grain sizes (< 5 µm) and the diversity of phases are challenging for the analysis. Furthermore, in contrast to natural materials the analysis of secondary materials faces the challenge of developing new methods for non-natural extreme combinations of elements and phases. Initial results of ash and slag samples will be presented and evaluated.

The identification and accurate characterisation of platinum-group minerals (PGMs) is usually a very cumbersome procedure due to their small grain size (typically below 10 µm) and inconspicuous appearance under reflected light. A novel strategy for finding and quantifying PGMs by combining mineral liberation analysis (MLA), a point logging system and electron probe microanalysis (EPMA) was thus developed. As a first step, the PGMs are identified using the MLA. Grains identified as PGMs are then marked and coordinates recorded with the point logger are then transferred to the EPMA. Case studies e.g. from the platiniferous reefs (Merensky Reef and UG2) of the Bushveld Complex (South Africa) illustrate that the combination of MLA, point logger and EPMA results in the identification of a significantly (up to 20 times) higher number of PGM grains than by careful reflected light microscopy. The analysis of PGEs as major elements in PGMs or as trace elements in e.g. base metal sulfides by EPMA requires considerable effort. Due to the often significant overlaps between the X-ray spectra of almost all platinum-group and associated elements, X-ray lines suitable for quantitative analysis need to be carefully selected. As peak overlaps cannot be avoided completely, an offline overlap correction based on weight proportions has been developed. A reliable overlap correction is of particular importance e.g. in Ru-sulfides as laurite if the overlapped element is a trace element (Rh) and the overlapping element is a major constituent (Ru). Results obtained with the procedure attain acceptable totals and atomic proportions, indicating that the applied corrections are appropriate.

Secondary raw materials (SRM) are becoming increasingly more important in ensuring the stability of critical metal supply. Like for natural raw materials, processing and metallurgical treatment demands a detailed and meticulous geometallurgical characterisation. Unlike municipal solid waste and Waste Electrical and Electronic Equipment (WEEE), ashes, slags, dusts and other industrial residues are "produced" centrally in large quantities. In light of these circumstances, the logistics of supply is simpler. This makes these types of SRM ideal candidates for the extraction of critical metals. Precise and accurate chemical and mineralogical data, knowledge of distribution of valuable and deleterious elements in the single phases as well as information about homogeneity and grain size distribution of the minerals are crucial for the development of new extraction technologies. Gaining these essential information can be achieved by using SEM-based automated mineralogical analysis. However, the large particle size range, the dominance of very small grain sizes (< 5 µm) and the diversity of phases are challenging for the analysis. Furthermore, in contrast to natural materials the analysis of secondary materials faces the challenge of developing new methods for non-natural extreme combinations of elements and phases. To overcome these challenges we used complementary analytical methods, like XRD and optical microscopy. Two of them, High-Speed PIXE and the “MEGA” instrument are still in the stage of development. Both instruments deliver additional information about trace element distribution. Nevertheless, in contrast to natural materials the analysis of secondary materials faces the challenge of developing new methods for non-natural extreme combinations of elements and phases. We present initial results of ash and slag samples, like residues of pyrometallurgical recycling of spent lead batteries.

Neves-Corvo is a world-class volcanic-hosted massive sulphide (VHMS) deposit located in the Iberian Pyrite Belt (IPB). It is both one of the largest and richest deposits in the IPB. Besides its size, other notable features include its high tin content and the unusual ore types within which most of this tin was originally hosted. High indium concentrations (30 - 50 ppm in whole ore) also make it an attractive source of this rare metal. However, the mine does not currently profit from this potential. It was the aim of this study to generate the data required for a detailed quantitative evaluation of different valorisation options for indium at Neves-Corvo. In addition to data on the spatial distribution of the element, this also requires a detailed understanding of its mineralogical deportment. While previous studies had reported elevated indium concentrations in a number of different minerals (e.g. stannite, sphalerite, cassiterite, tetrahedrite-tennantite, chalcopyrite) as well as the occurrence of two discrete indium minerals (roquesite, CuInS2, and sakuraiite, (Cu, Zn, Fe)3(In,Sn)S4), modal mineralogy and consequently the deportment of indium in the studied samples were never quantified. In the present work, a combination of whole ore geochemistry, automated scanning electron microscope (SEM)-based image analysis and electron probe microanalysis (EPMA) was used to study the mineralogical deportment of indium in a representative set of more than 70 ore and process samples. It was found that, depending on ore type, sphalerite and/or chalcopyrite are the most important host minerals while stannite, roquesite and sakuraiite are not important due to their generally low abundance. Indium concentrations in sphalerite are highly variable, but are usually 2 - 3 times higher than in coexisting chalcopyrite. The exact concentrations depend on the total concentration of indium in the ore in relation to the abundance of these two minerals. This apparent equilibrium partitioning behaviour is thought to be mostly a consequence of the extensive syntectonic recrystallisation of the ore minerals. The clear dominance of sphalerite and chalcopyrite as indium carriers has obvious consequences for valorisation options at the mine. First, the indium contained in the ores should be recoverable from the ores with the zinc and copper concentrates. Second, the production of separate concentrates enriched to the minimum concentrations required by smelters will only be possible by the separate processing of indium-rich ores. To the best knowledge of the authors, this is the first detailed deportment study for indium ever conducted. The results have obvious implications not only for indium valorisation at Neves-Corvo, but also in other massive sulphide deposits affected by extensive tectonically induced recrystallisation. They should therefore be of interest to the wider geometallurgical and economic geology communities. This is a contribution to the ZHINC project (PTDC/CTE-GIX/114208/2009). Thanks are due to the authors' host institutions for the provision of the funding and infrastructure necessary to conduct this work.

The Central European Kupferschiefer constitutes one of the most important natural copper sources in Europe (Borg et al. 2012). The Kupferschiefer sensu strictu challenges conventional exploitation due to its organic load, complex mineralogy and fine dispersion of ores. Thus alternative beneficiation strategies are investigated. Bioleaching – the use of microorganisms or microbial metabolites for metal solubilisation from ore material – may serve as an efficient and environmentally benign approach. Among others leaching with microbially produced organic acids provided good results (Anjum et al 2010). In previous studies (Kostudis et al. 2015) leaching of copper from Kupferschiefer sensu strictu (Polkowice Mine, Lubin, Poland) using glutamic acid was examined. It was shown that copper is primarily released from chalcocite (Cu2S) being the main copper mineral in the shale sample. However, decrease in chalcopyrite (CuFeS2) and bornite (Cu5FeS4) content by 40 % and 37 %, respectively, has also been reported as well as formation of secondary minerals such as covellite (CuS). As the Kupferschiefer sensu strictu is constituted very complexly investigation of the single main copper minerals without the matrix is worthwhile. Thus the current study addresses the influence of organic acids on chalcocite, bornite and chalcopyrite. Experiments were performed using strewn slides prepared as thick sections. Ore samples of chalcopyrite, bornite and chalcocite were provided from Ashio/Japan; Butte/Montana/USA and Henderson Mine/Namaqualand/South Africa, respectively. The samples (fig. A) were analysed prior to and after leaching with citric and glutamic acid using mineral liberation analysis (MLA) consisting of combined SEM and ED X-ray spectrometry and a specific software for automated data acquisition (fig. B), micro-Raman spectroscopy (fig. C), and atomic force microscopy (fig. D). The presentation shows results of comprehensive mineralogical analysis of both pristine and processed copper ores.

The Central European Kupferschiefer deposit bearing copper up to five percent is the most important natural copper resource in Europe, and thus raised again interest of both industry and science. Due to the complex composition of the shale including copper and sulfide rich ores, carbonates and organic compounds there is no efficient biotechnological approach applied yet. Although promising approaches using acidophilic micoorganisms were presented [1] issues such as acid pretreatment and resulting gypsum waste remain. Thus leaching at neutral and alkalic pH ranges has been investigated using both foreign and indigenous species including yeasts [2-4]. Especially usage of microbially produced organic acids [5] has shown good results regarding copper recovery. In previous studies [4] the impact of glutamic (see figure) and citric acid on copper minerals in Kupferschiefer ore has been examined using bulk chemicals. The presentation compares those results to copper leaching with citric acid as biotechnologically produced product in fermentation broth produced by the yeast Yarrowia lipolytica.

Die Kupferschiefervorkommen Mitteleuropas stellen eine anspruchsvolle lokale Ressource von Basismetallen wie Kupfer, aber auch strategischen Elementen wie Gallium oder Molybdän dar. Um diese Wertstoffe aus dem Kupferschiefer umweltfreundlich und effizient zu gewinnen, werden biotechnologische Laugungsverfahren untersucht. Die klassische Biolaugung, die säureliebende Mikroorganismen verwendet, stößt beim Kupferschiefer aufgrund hoher Karbonatgehalte von bis zu 18 % (Material aus Polkowice, Polen)an ihre Grenzen, da der optimale mikrobielle pH-Bereich um pH 2 überschritten wird. Daher werden alternative Verfahren getestet; so beispielsweise die Produktion organischer Säuren wie Glutamin- oder Zitronensäure durch Mikroorganismen. Hier wurden mithilfe von Schimmelpilzen bereits gute Kupferausbeuten aus Material des Kupferschiefertyps erzielt. Allerdings konnte in eigenen Arbeiten gezeigt werden, dass bei der Verwendung organischer Säuren die Laugungseffektivität im neutralen pH-Bereich höher ist als im schwach sauren Milieu. Daher stellt der Beitrag Ergebnisse zur Biolaugung von Kupfer aus Kupferschiefer im neutralen pH-Bereich vor. Dabei werden sowohl geochemische als auch mineralogische Daten präsentiert.

Die steigende Nachfrage an Basismetallen wie Kupfer, aber auch strategischen Elementen wie Gallium oder Molybdän, steht einer verringerten Qualität und erhöhter Komplexität vorhandener Erzressourcen gegenüber. Biotechnologische Ansätze wie die Biolaugung können auch mit diesem Ausgangsmaterial effiziente Abbauprozesse liefern. So konnten mithilfe von Schimmelpilzen und organischen Säuren vielversprechende Ergebnisse in der Kupferlaugung aus Kupferschiefer (Polkovice/Lubin, Polen) erzielt werden. Der europäische Kupferschiefer ist eine potente lokale Ressource und zeichnet sich durch hohe Anteile organischer Verbindungen und Carbonate, eine komplexe Matrix und maximalen Kupferkonzentrationen von ca. 5 % aus. Insbesondere der hohe Carbonatgehalt von ca. 18 % bringt die herkömmlichen Biolaugungsverfahren mit säureliebenden Bakterien an ihre Grenzen. Der Beitrag zeigt die Auswirkungen der Säureeinwirkung auf die Mineralogie des Kupferschiefers. Vornehmlich wird Chalkosin gelaugt, aber auch Kupfereisensulfide wie Bornit und Chalkopyrit. Die Gesamtkupferausbeute liegt bei durchschnittlich 44 % in einfachen Ansätzen in Schüttelkolben.

The Sn–W greisen deposits, located in the eastern part of the Variscan metallogenic Erzgebirge province (zinnwaldite Ar–Ar ages between 313 and 315 Ma), are emplaced in highly metamorphosed and/or igneous rocks and typically are associated with post-collisional Li–F-enriched small granitic intrusions. This metallogenic province traditionally belonged to the major source of economic Sn, Ag, U, W, Co and fluorite–barite deposits for central Europe. The Zinnwald/Cínovec Li–Sn greisen deposit is associated with a unique zinnwaldite–quartz–topaz mineralization hosted by an albitized stock-granite. Li contents and isotope compositions were measured in host albite granites (n=2), greisens (n=3), and a sample from a flat-dipping vein in the Zinnwald deposit, paralleled by individual mineral phases. All investigated bulk rocks have extreme Li contents reaching from 1,600–2,200 ppm in albite-granite, to 3,400–6,200 ppm in greisen-type rocks and to ~8,000 ppm in a vein-type sample, most likely carried by zinnwaldite (15,000–19,200 ppm) and muscovite (9,500–15,700 ppm) whereas albite and quartz, in particular, have significantly lower Li abundances (560–660 and 33–330 ppm, respectively). The high bulk Li contents are very unusual even for chemically evolved granitic systems with the exception of Li-rich pegmatites. Bulk 7Li values are restricted (–1.0 to 0.3 ‰), consistent with late orogenic granites from a larger area of the Erzgebirge Mts.. Zinnwaldite and muscovite carry isotopically heavy Li relative to the corresponding bulk rocks and, at the same time, muscovite always is slightly heavier than zinnwaldite. 7Li values of quartz become progressively heavier from granites through greisens to a vein sample. Zinnwaldite may represent a late-stage ingress of Li-rich fluids/melts rather than indigenous phase of these lithologies because from mass balance considerations and mineral modes, bulk [Li] and 7Li values cannot easily be reconstructed for either sample of the suite.