Pyrometallurgical upgrading of PGM-rich leach residues from the Western Platinum Base Metals Refinery through roasting

Show simple item record Bezuidenhout, Gert Adrian Eksteen, J.J. Akdogan, G. Bradshaw, S.M. De Villiers, J.P.R. (Johan) 2014-02-28T11:45:41Z 2014-02-28T11:45:41Z 2013-11
dc.description.abstract The production of Platinum Group Metals (PGMs) normally entails the smelting of PGM flotation concentrates, converting of the furnace matte and removal of the bulk of the Ni, Cu, Co, S and Fe through atmospheric and pressure leaching in a base metals refinery to produce a PGM-rich concentrate. A number of impurities, mostly Se, Te, As, Bi, Os and Pb, are not removed significantly during the oxidising leach process in sulphuric acid media. In addition slag inclusions in matte leads to contamination of the PGM residues with silica, fayalite, magnetite and trevorite phases. Furthermore some Cu, Ni, Fe and S also remain. For this reason a typical Precious Metal Refinery (PMR) feed material contains less than 65% PGMs. The PMR is based on a chloride process and requires contaminants to be within narrow specification limits to prevent the formation of PGM residues that must be reprocessed or tolled, leading to poor first pass metal efficiencies and extending the duration of the production pipeline for efficient recovery. A process has been developed to significantly upgrade the BMR leach residues through pyrometallurgical processing, which include a multistep process of roasting under oxidising atmospheres, a two-step smelting process of the roasted calcine (with engineered slag chemistry and slag-refractory interactions) and subsequent atomisation of the molten alloy which can be fed as a slurry into the HCl/Cl2 dissolution reactors in the precious metals refinery. These pyrometallurgical steps upgrade the BMR residue from a 45–50% grade up to an alloy grade of ca. 90% PGMs, whilst removing the most deleterious elements with major process impacts on the PMR. This paper will focus primarily on the roasting step and it will investigate the thermochemical and mineralogical changes occurring during roasting. These changes were evaluated through a combination of thermochemical modelling and experimental investigation. The roasting step needs to be in an oxidative environment in order to achieve the vapourisation of Se, Te, As, Os and S. The speciation of PGMs and their vapourisation behaviour are presented, as well as the sensitivity of precious metals deportment to changes in roast conditions. en
dc.description.librarian hb2014 en
dc.description.librarian ai2014
dc.description.uri en
dc.identifier.citation Bezuidenhout, GA, Eksteen, JJ, Akdogan, G, Bradshaw, SM & De Villiers, JPR 2013, 'Pyrometallurgical upgrading of PGM-rich leach residues from the Western Platinum Base Metals Refinery through roasting', Minerals Engineering, vol. 53, pp. 228-240. en
dc.identifier.issn 0892-6875 (print)
dc.identifier.issn 1872-9444 (online)
dc.identifier.other 10.1016/j.mineng.2013.04.002
dc.language.iso en en
dc.publisher Elsevier en
dc.rights © 2013 Elsevier Ltd.. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Minerals Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Minerals Engineering, vol. 53, pp. 228-240, 2013. doi : 10.1016/j.mineng.2013.04.002 en
dc.subject PGM concentrate en
dc.subject Leach residue en
dc.subject Volatiles en
dc.subject PGM oxidation en
dc.subject Platinum Group Metals (PGMs) en
dc.subject.lcsh Platinum group -- Metallurgy en
dc.subject.lcsh Platinum group -- South Africa -- Metallurgy en
dc.subject.lcsh Platinum mines and mining -- South Africa en
dc.subject.lcsh Roasting (Metallurgy) en
dc.subject.lcsh Pyrometallurgy en
dc.subject.lcsh Metals -- Inclusions en
dc.title Pyrometallurgical upgrading of PGM-rich leach residues from the Western Platinum Base Metals Refinery through roasting en
dc.type Postprint Article en

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