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News Article | November 14, 2016
Site: www.eurekalert.org

Copper and other non-ferrous metals cannot be fully broken down in mines, and residues of the valuable metals remain even after the metallurgical processes that follow. Residues are stored on tailings. The new German-Polish research project NOMECOR has two aims, namely to reclaim the metals as well as to make the mineral components of the tailings usable for cement production. The Federal Ministry for Research and Education is funding the research project for three years with approximately 500,000 euros. This is coordinated by the Helmholtz Institute Freiberg for Resource Technology (HIF) at the Helmholtz-Zentrum Dresden-Rossendorf as well as the Polish Institute for Non-ferrous Metallurgy (IMN). "The project intends to improve access to copper, a socio-economically important bulk metal," says project coordinator Dr Stefan Dirlich from the Freiberg Helmholtz Institute. Copper is expensive and in great demand, as it is used for electric wiring and machines, as well as for alloys such as brass or bronze. However, mining it is becoming increasingly difficult as the metal content in the ores is very low nowadays. The project is targeting several aims simultaneously as far as sustainability is concerned: greater resource efficiency by recycling the metals from tailings, and regaining natural areas by reducing tailings. The Karlsruhe Institute of Technology, the G.E.O.S. Ingenieurgesellschaft mbH and the Polish enterprise Hydrogeometal PK are also involved in the project. Bio-technicians working at the Helmholtz Institute want to use microorganisms to remove copper and other valuable metals from tailings. The research partners at IMN and GEOS intend to test the chemical methods for this. Furthermore, they will investigate how pure metals separate from dissolved copper ores and how further residues can be minimised. In this project, scientists from the Karlsruhe Institute of Technology want to investigate whether mineral tailing deposits are suitable for the production of cement. With this project, the Helmholtz Institute in Freiberg is enhancing its research into recycling reusable materials from mining waste sites. Apart from natural mineral deposits, these may become important secondary sources of raw materials in future, especially as there are tailings everywhere in the world where mining was or is carried out. The project partners want to work with sample materials from a flotation tank which is currently being developed in a Polish mine. All residues which result during the enrichment (flotation) of copper and other valuable metals to a metal concentrate are deposited in such pools. The residues eventually pile up in tailings; their volumes are many times greater than the amount of metal extracted. About 2.4 million tons of copper still remain in tailings of non-ferrous mines in Poland, which also includes copper. Only coal mines have a greater number of tailings. The kick-off for the NOMECOR research project recently took place in the Polish town of Poznan as part of the status seminar on STAIR - the programme for German-Polish research on sustainability. All funded programmes to date were introduced at this event. NOMECOR is part of the second round of funding and the only research project in the field of resource efficiency. The Helmholtz-Zentrum Dresden-Rossendorf (HZDR) conducts research in the sectors energy, health, and matter. The HZDR has been a member of the Helmholtz Association, Germany's largest research organization, since 2011. It has four locations (Dresden, Leipzig, Freiberg, Grenoble) and employs about 1,100 people - approximately 500 of whom are scientists, including 150 doctoral candidates. The Helmholtz Institute Freiberg for Resource Technology (HIF) pursues the objective of developing innovative technologies for the economy so that mineral and metalliferous raw materials can be made available and used more efficiently and recycled in an environmentally friendly manner. The HIF was founded in 2011, belongs to Helmholtz-Zentrum Dresden-Rossendorf and is cooperating closely with TU Bergakademie Freiberg.

Smith A.J.B.,University of Johannesburg | Beukes N.J.,University of Johannesburg | Gutzmer J.,University of Johannesburg | Gutzmer J.,Helmholtz Institute Freiberg for Resource Technology
Economic Geology | Year: 2013

This paper documents the sedimentological setting, mineralogy, and geochemistry of several iron formation units interbedded with siliciclastic strata of the Mesoarchean Witwatersrand Supergroup, well known for its world-class conglomerate-hosted Au-U deposits. Four major iron formation beds, with associated magnetic mudstones, are present in two distinctly different lithostratigraphic associations, namely shale- and diamictite-associated iron formation. The shale association is represented by the Water Tower and Contorted Bed iron formations in the Parktown Formation of the Hospital Hill Subgroup in the lower part of the succession and the diamictite association by the Promise and Silverfield iron formations in the overlying Government Subgroup. The iron formation units have been subjected to lower greenschist facies metamorphism. Oxide (magnetite and limited hematite), carbonate, and silicate facies iron formations are recognized. The iron formations typically overlie major transgressive flooding surfaces in the succession and, in turn, form the base of progradational coarsening-upward increments of sedimentation comprising magnetic mudstone, nonmagnetic shale, and interbedded siltstone-quartzite. The upward transition from iron formation into magnetic mudstone is accompanied by a change in mineralogical composition from hematite-magnetite iron formation at the base in the most distal setting through magnetite-siderite- and siderite-facies iron formation in the transition zone to magnetic mudstone. The siderite with associated ankerite displays highly depleted δ13C values, suggesting crystallization via iron respiration in presence of organic carbon. The iron formations display positive post-Archean Australian shale-normalized Eu and Y anomalies with depletion in light rare-earth elements relative to heavy rare-earth elements, indicating precipitation from marine water with a high-temperature hydrothermal component. Integration of sedimentological, petrographic, and geochemical results indicates that the shale-associated iron formation was deposited during the peak of transgression, when reduced iron-rich hydrothermal waters entered the Witwatersrand Basin over a limited vertical extent due to neutral buoyancy, with the top of the plume occurring below the photic zone. It is suggested that chemolithoautotrophic iron-oxidizing bacteria, which would have been able to exploit the difference in chemistry between the iron-enriched plume water and ambient ocean water to fuel metabolic activity in the presence of limited free molecular oxygen, were responsible for precipitation of initial ferric iron oxyhydroxides. The vertical facies associations in the iron formations most likely developed in response to the limited vertical extent of the hydrothermal plume, with (from distal to proximal) hematite preserved where the base of the plume was not in contact with the basin floor, magnetite where the plume water was in contact with bottom sediment, iron-rich carbonates where organic carbon input was high, iron-rich alumosilicates where siliciclastic input became significant in more proximal settings, and iron-poor sediment above the top of the plume. Diamictite-associated iron formations in the Witwatersrand are inferred to have been deposited in a fashion similar to the shale-associated iron formations, with the exception that major transgressions and hydrothermal plume invasion were preceded by glacial ice cover. The climate warming and increased volcanic activity required could have been related to increased tectonic activity inferred for the Witwatersrand Supergroup during deposition of the glacially associated iron formations. © 2013 Society of Economic Geologists, Inc.

Klossek P.,Helmholtz Institute Freiberg for Resource Technology | Van Den Boogaart K.G.,Helmholtz Institute Freiberg for Resource Technology
International Journal of Mining and Mineral Engineering | Year: 2015

When the rare earth prices skyrocketed in 2011, over 400 exploration projects appeared in the rest of the world (ROW). Before an exploration project comes into production, it has to pass through various stages of project development and face multiple challenges at each of these stages. According to Cooper's stage-gate system, a decision about whether to move on to the next project stage should be based on the evaluation of certain criteria. The case of rare earth elements (REEs), however, differs from other metals in terms of mineralogy, market, technology, environmental issues and strategic importance. Therefore, the decision criteria might also partly differ. To find these criteria for the case of rare earths, interviews with decision-makers from several rare earths projects at different stages of development were conducted. In this paper, obtained criteria are listed, explained and analysed for each stage/gate. Suggestions about their application to project management are made. Copyright © 2015 Inderscience Enterprises Ltd.

Rudolph M.,Helmholtz Institute Freiberg for Resource Technology | Peuker U.A.,Institute of Mechanical Process Engineering and Minerals Processing
Chemie-Ingenieur-Technik | Year: 2014

The mineral separation process flotation is fundamentally relying on hydrophobic interactions, which are still not entirely understood and heavily discussed in literature. Here, various possibilities to determine hydrophobic properties of mineral surfaces in water using the concept of colloidal probe atomic force microscopy are introduced. The method is based on the accepted theories of the hydrophobic effect of hydrophobic surfaces in water. Additionally, the hydrophobic parameters are correlated with microflotation experiments for magnetite and quartz surfaces. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Reuter M.A.,Helmholtz Institute Freiberg for Resource Technology
Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science | Year: 2016

Metallurgy is a key enabler of a circular economy (CE), its digitalization is the metallurgical Internet of Things (m-IoT). In short: Metallurgy is at the heart of a CE, as metals all have strong intrinsic recycling potentials. Process metallurgy, as a key enabler for a CE, will help much to deliver its goals. The first-principles models of process engineering help quantify the resource efficiency (RE) of the CE system, connecting all stakeholders via digitalization. This provides well-argued and first-principles environmental information to empower a tax paying consumer society, policy, legislators, and environmentalists. It provides the details of capital expenditure and operational expenditure estimates. Through this path, the opportunities and limits of a CE, recycling, and its technology can be estimated. The true boundaries of sustainability can be determined in addition to the techno-economic evaluation of RE. The integration of metallurgical reactor technology and systems digitally, not only on one site but linking different sites globally via hardware, is the basis for describing CE systems as dynamic feedback control loops, i.e., the m-IoT. It is the linkage of the global carrier metallurgical processing system infrastructure that maximizes the recovery of all minor and technology elements in its associated refining metallurgical infrastructure. This will be illustrated through the following: (1) System optimization models for multimetal metallurgical processing. These map large-scale m-IoT systems linked to computer-aided design tools of the original equipment manufacturers and then establish a recycling index through the quantification of RE. (2) Reactor optimization and industrial system solutions to realize the “CE (within a) Corporation—CEC,” realizing the CE of society. (3) Real-time measurement of ore and scrap properties in intelligent plant structures, linked to the modeling, simulation, and optimization of industrial extractive process metallurgical reactors and plants for both primary and secondary materials processing. (4) Big-data analysis and process control of industrial metallurgical systems, processes, and reactors by the application of, among others, artificial intelligence techniques and computer-aided engineering. (5) Minerals processing and process metallurgical theory, technology, simulation, and analytical tools, which are all key enablers of the CE. (6) Visualizing the results of all the tools used for estimating the RE of the CE system in a form that the consumer and general public can understand. (7) The smart integration of tools and methods that quantify RE and deliver sustainable solutions, named in this article as circular economy engineering. In view of space limitations, this message will be colored in by various publications also with students and colleagues, referring to (often commercial) software that acts as a conduit to capture and formalize the research of the large body of work in the literature by distinguished metallurgical engineers and researchers and realized in innovative industrial solutions. The author stands humbly on the shoulders of these developments and their distinguished developers. This award lecture article implicitly also refers to work done while working for Ausmelt (Australia), Outotec (Finland and Australia), Mintek (South Africa), and Anglo American Corporation (South Africa), honoring the many colleagues the author has worked with over the years. © 2016 The Minerals, Metals & Materials Society and ASM International

Frenzel M.,Helmholtz Institute Freiberg for Resource Technology | Woodcock N.H.,University of Cambridge
Journal of Structural Geology | Year: 2014

Cockade breccias are fault fills in which individual clasts are completely surrounded by concentric layers of cement. They occur particularly in low-temperature near-surface hydrothermal veins. At least six mechanisms have been proposed for the formation of cockade breccia-like textures, but only two - repeated rotation-accretion, and partial metasomatic replacement of clast minerals - have been supported by detailed evidence. A typical example of cockade breccia from the Gower Peninsula (South Wales) shows clear evidence for the rotation-accretion mechanism: in particular, overgrown breakage points in cement layers - where cockades were previously touching each other - and rotated geopetal infills of haematitic sediment. Based on the available evidence, it is proposed that cockade textures result from low rates of cement growth compared to high rates of dilational fault slip. Seven criteria are given for the correct identification of cockade breccias. © 2014 Elsevier Ltd.

Mockel R.,TU Bergakademie Freiberg | Mockel R.,Helmholtz Institute Freiberg for Resource Technology | Reuther C.,TU Bergakademie Freiberg | Gotze J.,TU Bergakademie Freiberg
Journal of Crystal Growth | Year: 2013

Rare earth element calcium oxoborates (REECOB, REECa4O[BO 3]3) represent a group of materials for non-linear optics and with useful piezoelectric properties under high-pressure and high-temperature conditions making it applicable as sensor materials in extreme environments. High-quality crystals with appropriate size are generally grown from a melt by the Czochralski method. This paper presents a compilation and comparison of crystal growth parameters and properties of members of the REECOB group from the literature with those of own growth experiments. Recent studies provided new data concerning the melting temperature of REECOB members, such as ca. 1475 °C for SmCa4O(BO3)3 (SmCOB). © 2013 Elsevier B.V. All rights reserved.

Rudolph M.,Helmholtz Institute Freiberg for Resource Technology
IMPC 2014 - 27th International Mineral Processing Congress | Year: 2014

Flotation is without a doubt one of the major processes for the separation of fine minerals and it has been applied for more than a century. A key task of a successful flotation separation is to find the proper chemical treatment to selectively hydrophobize and thus float a certain mineral phase using molecules or ions referred to as collectors, depressants, regulators and frothers. Commonly floatability is determined by microflotation tests using the Hallimond tube with pure mineral phases. This method however requires the pure mineral phase which is very often not even taken from the same deposit which is going to be processed. In this paper we present a new approach to in-situ determine and even map the floatability of finely disseminated mineral phases within crosssections of an ore. It is based on measuring hydrophobic effects using colloidal probe atomic force microscopy with a hydrophobic polystyrene probe based on force spectroscopy with a lateral resolution of only a few nanometers. Coupled confocal Raman spectroscopy on the same locality enables the identification of the mineral phase. We present the working principles of the method and show which signals in the force spectra characteristic for hydrophobic interactions can be used to define floatability and which can then be mapped as single quantities, e.g. jump-into-contact events due to nanobubble occurrence or parameters of the long range interaction curves most probably due to capillary effects. A finely grained silicate ore containing the valuable rare earth mineral eudialyte from southern Sweden as well as pure samples of magnetite are presented as substrates to demonstrate the capability of this new approach. This method will not only help to find the proper flotation chemistry but it can furthermore help in researching and unravelling problems of floatability within similar mineral phases.

Tolosana-Delgado R.,Helmholtz Institute Freiberg for Resource Technology | van den Boogaart K.G.,Helmholtz Institute Freiberg for Resource Technology | van den Boogaart K.G.,TU Bergakademie Freiberg
Mathematical Geosciences | Year: 2013

Geochemical surveys often contain several tens of components, obtained from different horizons and with different analytical techniques. These are used either to obtain elemental concentration maps or to explore links between the variables. The first task involves interpolation, the second task principal component analysis (PCA) or a related technique. Interpolation of all geochemical variables (in wt% or ppm) should guarantee consistent results: At any location, all variables must be positive and sum up to 100 %. This is not ensured by any conventional geostatistical technique. Moreover, the maps should ideally preserve any link present in the data. PCA also presents some problems, derived from the spatial dependence between the observations, and the compositional nature of the data. Log-ratio geostatistical techniques offer a consistent solution to all these problems. Variation-variograms are introduced to capture the spatial dependence structure: These are direct variograms of all possible log ratios of two components. They can be modeled with a function analogous to the linear model of coregionalization (LMC), where for each spatial structure there is an associated variation matrix describing the links between the components. Eigenvalue decompositions of these matrices provide a PCA of that particular spatial scale. The whole data set can then be interpolated by cokriging. Factorial cokriging can also be used to map a certain spatial structure, eventually projected onto those principal components (PCs) of that structure with relevant contribution to the spatial variability. If only one PC is used for a certain structure, the maps obtained represent the spatial variability of a geochemical link between the variables. These procedures and their advantages are illustrated with the horizon C Kola data set, with 25 components and 605 samples covering most of the Kola peninsula (Finland, Norway, Russia). © 2013 International Association for Mathematical Geosciences.

Rudolph M.,Helmholtz Institute Freiberg for Resource Technology | Rudolph M.,TU Bergakademie Freiberg | Peuker U.A.,TU Bergakademie Freiberg
Journal of Nanoparticle Research | Year: 2012

A study is presented, where agglomerated magnetite nanoparticles with a crystallite size of 15 nm are transferred from water to an immiscible organic phase and tend to deagglomerate under certain conditions using different types of chemically adsorbing fatty acid. It is shown that the longer fatty acids lead to more stable dispersions and for the longest fatty acids, the functionality of the molecules defines stability with best results for ricinoleic acid. The disjoining force as a function of the brush layer thickness and adsorption density is calculated with a physical model applying the well-established Alexander de Gennes theory. We further investigate the colloidal stability of the transferred and stabilized magnetite nanocrystals in polymer solutions of destabilizing PMMA and stabilizing PVB. A DLVO-like theory presents the governing attractive and repulsive interactions for the case of destabilizing non-adsorbing polymers. The theory can be used to explain the influencing parameters in a mixture of sterically stabilized nanoparticles in an organic solvent based solution of polymer coils. Finally, by spray drying, we produce polymer-nanoparticle composite microparticles. Based on BET, laser diffraction and backscatter electron SEM measurements, we draw conclusions on the nanoparticle distribution within the composite in correlation with the stability investigations. © 2012 Springer Science+Business Media B.V.

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