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Investigations on the Detectability of Rare-Earth Minerals Using Dual-Energy X-ray Transmission Sorting

  • Thematic Section: Green Rare Earth Elements—Innovations in Ore Processing, Hydrometallurgy, and Electrolysis
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Abstract

Mechanical processing of rare-earth ore types typically requires very high-energy consuming steps such as grinding to liberate valuable minerals. In addition, occasionally harmful reagents are used in processes such as flotation to separate the contained minerals. Sensor-based sorting (SBS), a technology used for coarse particle separation (ca. +10–20 mm), can play a key role in reducing mass flows and increase valuable contents at an early stage of the process chain, with positive effects on the following processes. One sensor-technology used in SBS is dual-energy X-ray transmission (DE-XRT) sorting. The principle is known from luggage safety inspections at airports and has already been adapted to the sorting of numerous commodities in the raw materials sector, such as coal, gold ore and tungsten ores. The technical applicability of DE-XRT sorting is limited to ore types for which differences in the valuable/metal contents are detectable, based on an interpretation of recorded X-ray images. Since variations in ore characteristics such as mineralogy, valuable content, and grain sizes of valuable minerals are typical, each ore has to be tested individually for the technical applicability of DE-XRT sorting. In a fundamental research project, influences of specific parameters on the detectability of rare-earth minerals were investigated based on practical test works with artificial samples of defined, simplified composition, followed by an interpretation of recorded X-ray images. Influences such as rare-earth concentrations, grain sizes and spatial distribution of valuable minerals on the average X-ray attenuation were investigated. Limits and potentials of this fundamental approach are presented. Besides the above, the ability to simulate X-ray absorption characteristics, based on a Monte Carlo simulation approach was tested. X-ray absorption features of defined particle compositions were calculated, and virtual X-ray images were produced. Results of both measurement approaches were compared to assess the general technical feasibility of the computer-based simulation.

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Notes

  1. The REO-contents of both minerals were measured by Lithium Metaborate Fusion ICP-MS analysis.

  2. A computer tomography analysis was conducted. Images showed agglomerations of bastnaesite in the 0–32-µm size class.

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Authors and Affiliations

  1. Unit of Mineral Processing, RWTH Aachen University, Lochnerstrasse 4-20, 52064, Aachen, Germany

    Kilian Neubert & Hermann Wotruba

Authors
  1. Kilian Neubert
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  2. Hermann Wotruba
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Correspondence to Kilian Neubert.

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The contributing editor for this article was Bernd Friedrich.

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Neubert, K., Wotruba, H. Investigations on the Detectability of Rare-Earth Minerals Using Dual-Energy X-ray Transmission Sorting. J. Sustain. Metall. 3, 3–12 (2017). https://doi.org/10.1007/s40831-016-0069-1

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  • DOI: https://doi.org/10.1007/s40831-016-0069-1

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