The recovery of platinum group metals from low-grade concentrates to an iron alloy using silicon carbide as reductant
Date
2015
Journal Title
Journal ISSN
Volume Title
Publisher
The Southern African Institute of Mining and Metallurgy
Abstract
The purpose of the study was to investigate the feasibility of SiC reduction of low-grade concentrates from Lonmin’s Rowland and Easterns operations with respect to metal fall and PGM recovery. These concentrates are rich in SiO2 and MgO with low concentrations of chalcopyrite and Cr2O3. Pd is the most abundant of the PGMs. SiC reduction of samples was conducted at 1600℃ with 2.5–3.5 kg SiC per 100 kg concentrate. PGM recoveries for Easterns concentrate were better than for Rowland. More than 85% of the Ir and Pd and almost 60% of the Pt were recovered with 3.5 kg SiC per 100 kg concentrate. SEM of slag samples showed little entrainment of metallic prills compared to Rowland samples. This was attributed to the relatively higher melt viscosities of the Rowland concentrate. In order to decrease slag viscosity and to enhance PGM recovery, the FeO content of the Easterns concentrate was increased with the addition of 10 kg converter slag per 100 kg concentrate. Ir and Pd
recoveries were increased to about 95%, while Pt recovery was around 70%. On the basis of these results an optimum feed ratio between Easterns and Rowland concentrates and converter slag is proposed. Carbothermic reduction of the optimum charge was also compared to SiC reduction. Carbothermic reduction yielded a marginally higher metal fall; however, the calculated gas emissions and energy requirements were higher than for SiC reduction.
Description
CITATION: Malan, W., et al. 2015. The recovery of platinum group metals from low-grade concentrates to an iron alloy using silicon carbide as reductant. Journal of the Southern African Institute of Mining and Metallurgy, 115(5): 375-383.
The original publication is available at http://www.saimm.co.za
The original publication is available at http://www.saimm.co.za
Keywords
Platinum group metals, Iron alloys, Silicon carbide
Citation
Malan, W., et al. 2015. The recovery of platinum group metals from low-grade concentrates to an iron alloy using silicon carbide as reductant. Journal of the Southern African Institute of Mining and Metallurgy, 115(5): 375-383