Jens Gutzmer

Electron Probe Microanalysis of REE in Eudialyte Group Minerals: Challenges and Solutions

Accurate quantification of the chemical composition of eudialyte group minerals (EGM) with the electron probe microanalyzer is complicated by both mineralogical and X-ray-specific challenges. These include structural and chemical variability, mutual interferences of X-ray lines, in particular of the rare earth elements, diffusive volatility of light anions and cations, and instability of EGM under the electron beam. A novel analytical approach has been developed to overcome these analytical challenges. The effect of diffusive volatility and beam damage is shown to be minimal when a square of 20×20 µm is scanned with a beam diameter of 6 µm at the fastest possible speed, while measuring elements critical to electron beam exposure early in the measurement sequence. Appropriate reference materials are selected for calibration considering their volatile content and composition, and supplementary offline overlap correction is performed using individual calibration factors. Preliminary results indicate good agreement with data from laser ablation inductively coupled plasma mass spectrometry demonstrating that a quantitative mineral chemical analysis of EGM by electron probe microanalysis is possible once all the parameters mentioned above are accounted for.

Current Status of Natural Resources—An Overview

Two scenarios must be distinguished in an assessment of the supply of natural resources: the supply from domestic sources and the supply from foreign sources.

The Raw Material Requirements for Energy Systems

The new energy systems will be significantly more diverse as compared to the traditional energy technologies. Increasingly distinctive and mostly decentralized technologies will be added to the traditional generating technologies, such as coal and natural gas power stations, that dominate today’s energy systems.

Supply of Raw Materials and Effects of the Global Economy

The availability of raw materials is influenced by the supply- and demand-sides. Furthermore, the supply of raw materials—in general and including those for the new energy systems of the future—is dependent on developments in the global mining business and global economy. Political guidance can play an important role in this situation.

The inherent link between ore formation and geometallurgy as documented by complex tin mineralization at the Hämmerlein deposit (Erzgebirge, Germany)

A comprehensive quantitative mineralogical study on the Hämmerlein tin deposit in the Erzgebirge, Germany, not only yields insights into the genesis of Sn mineralization but also provides also important clues for beneficiation. The lithological units of the skarn and greisen deposit show significant differences in modal mineralogy and Sn deportment. These systematic differences are attributed to several stages of ore formation. Of greatest significance is a paragenetically late cassiterite-chlorite-fluorite-sulfide assemblage. This assemblage replaces pre-existing skarn lithologies and also forms stockwork mineralization in greisen-type ores developed at the expense of mica schist that surrounds the skarn. The co-genetic formation of the cassiterite-chlorite-fluorite-sulfide assemblage is captured by the mineral association parameter—a parameter that can be easily quantified from data acquired during automated mineralogy studies. To document the preferred mineral association, a ratio is introduced that illustrates how closely cassiterite—the only Sn mineral of economic relevance—is associated with chlorite, fluorite, and sulfides. This so-called MAMA ratio illustrates the strongly preferred association between cassiterite and chlorite. The results also illustrate that the abundance of rock-forming chlorite may be used as a proxy for the abundance of the much less common cassiterite. This proxy is well-suited to sort ore from poorly mineralized/unmineralized rock fragments early during the beneficiation process. Such separation may well be achieved by using a short wave infrared detector that is already deployed in commercially available sorting equipment. The case study illustrates the inherent link between the processes responsible for ore genesis, the definition of geometallurgical domains, and the selection of suitable beneficiation strategies.

Major and trace element geochemistry of the European Kupferschiefer – an evaluation of analytical techniques

Simple and rapid techniques are needed for routine quantitative chemical bulk-rock analyses of Kupferschiefer, a black shale containing variable amounts of silicates, base metal sulphides, carbonates and an organic content of up to 30 weight percent. In this study, WD-XRF, TXRF, and ICP-OES of acid- as well as peroxide-digested samples were tested as potential techniques based on their availability and adaptability to analyse major (Si, Ti, Al, Mg, Ca, Fe, K, but also Cu, Zn, Pb) and selected trace (Ag, As, Ba, Co, Mo, Ni, V) element concentrations. Because of the absence of a suitable reference material, a comparative study was undertaken using instrumental neutron activation analysis to ascertain the accuracy of different approaches. Our results suggest that data from ICP-OES were much higher in accuracy compared to INAA than those from WD-XRF and TXRF, independent of the digestion procedure. The choice of digestion procedure is reflected in low detection limits but an underestimation of Cu, Ag, Co, and V concentrations reported by ICP-OES relative to those obtained by INAA in the case of acid digestion and increased detection limits coupled with a loss of over 25% Ag relative to INAA for peroxide digestion. Supplementary material: Geochemical data, list of irradiation times and measured isotopes can be found at https://doi.org/10.6084/m9.figshare.c.4015507

Particle-based Sb distribution model for Cu–Pb flotation as part of geometallurgical modelling at the polymetallic Rockliden deposit, north-central Sweden

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 the distribution of Sb minerals in a laboratory flotation test based on different degrees of details in the mineralogical information of the flotation feed. Experimental data obtained from four composites were used for the modelling and simulation. The following different simulation levels were run (sorted from least to highest level of detail of their mineralogical information): chemical assays, unsized bulk mineralogy, sized bulk mineralogy and particle information. It was shown that recoveries simulated based on bulk mineralogy are mostly within the error margin acceptable in the exploration stage of the Rockliden deposit. Unexpected high deviation in the simulation using particle information from the original recovery has been partly attributed to the fact that recovery of non-liberated particles cannot be modelled appropriately in the present version of the modelling and simulation software. It is expected that the implementation of full particle information in simulation will improve the Sb distribution model for the mineralogically complex Rockliden deposit.