Abstract
In the mineral processing industry, Ni-Cu-Fe-S converter matte is leached to remove base metals from a concentrate containing platinum group metals (PGMs). We investigated the atmospheric leaching process to develop a better understanding of the leaching behaviour of the base metals (Cu, Fe, and Ni) and the PGMs, in particular Ru, Ir, and Rh with respect to key process variables, acid concentration, and Cu concentration under oxidative and non-oxidative conditions. With oxidative leaching, a higher initial acid concentration resulted in higher Cu, Ni, and Fe extractions, as well as faster leaching reaction rates. A higher initial acid concentration also resulted in faster precipitation of Cu, Ru, and Ir under oxidizing conditions. Under non-oxidative conditions, Ni and Fe extraction was much slower, and the effect of initial acid concentration on Cu precipitation was less pronounced. The initial Cu concentration had a slightly smaller effect on the leaching behaviour of Fe and Ni, as well as precipitation of Ru, Ir and Rh. Moreover, a higher initial Cu concentration suppressed both Ni and Fe leaching and had a slight inhibiting effect on the precipitation behaviour of Cu, Ru, and Ir.
Highlights
The largest platinum group metal (PGM) deposit in the world, located in the Bushveld Complex in South Africa, holds half of the world’s platinum group elements (PGEs) and chromium
We investigated the atmospheric leaching process to develop a better understanding of the leaching behaviour of the base metals (Cu, Fe, and Ni) and the PGMs, in particular Ru, Ir, and Rh with respect to key process variables, acid concentration, and Cu concentration under oxidative and non-oxidative conditions
The PGMs present in the matte, along with the Cu, report to the leach residue. In this project we investigated the first stage atmospheric leaching process of the converter matte, using base metal refinery (BMR) spent electrolyte from Sibanye-Stillwater, in order to develop a better understanding of the effect of the initial acid and Cu concentrations on the leaching behaviour of the base metals, in particular Fe and Ni, as well as Rh, Ir, and Ru, under oxidative and non-oxidative conditions
Summary
The largest platinum group metal (PGM) deposit in the world, located in the Bushveld Complex in South Africa, holds half of the world’s platinum group elements (PGEs) and chromium. Smelting and processing of the PGM concentrates in this region is carried out by four major companies, namely Anglo American Platinum, Impala Platinum, Sibanye-Stillwater, and Northam Platinum (Jones, 2005) Due to their unique physical and chemical properties such as good corrosion and oxidation resistance, high melting temperatures, good conductivity, and electronic and catalytic properties, the PGMs are used for their superior performance in certain industries and markets. These applications include (i) platinum or rhodium as autocatalysts to reduce greenhouse gas emissions produced by the combustion of fossil fuels, (ii) platinum and palladium jewellery, (iii) catalysts in the chemical sector, (iv) electrical equipment and electronic devices, (v) platinum used in the manufacturing of glass, and the (vi) production of drugs in the medical sector (Creamer, 2006). Due to very little insight into the mechanisms of the atmospheric leaching process, studies conducted by Hofirek and Kerfoot (1992), Lamya and Lorenzen (2006), van Schalkwyk et al (2011) and Snyders et al (2018) were aimed at investigating the chemistry and mechanism of the process, as well as determining the effects of Fe endpoints, initial acid and Cu concentrations of the spent electrolyte solutions, and oxidative/non-oxidative conditions on the leaching behaviour of Ni-Cu-Fe-S converter mattes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Journal of the Southern African Institute of Mining and Metallurgy
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
