An investigation into electrochemical interactions between platinum group minerals and xanthate: Voltammetric study

In the flotation of platinum group minerals (PGMs) containing significant amounts of tellurides and arsenides it is generally assumed that these minerals will respond in the same way as sulphides to collectors such as xanthates which are typically used in sulphide flotation. This paper presents the results of a fundamental study which has been conducted to provide a greater insight into the comparative interactions between synthetic moncheite (PtTe2) and cooperite (PtS) with sodium ethyl xanthate (SEX). Cyclic voltammetry has been used to investigate these interactions in the absence and presence of sodium ethyl xanthate (SEX) in aerated and de-aerated solutions. Reduction potentials of the SEX/dixanthogen couple have been measured and compared to published data. Reduction potentials of possible reactions of the minerals have been predicted from thermodynamic calculations and used to attempt to interpret the potentials measured in the cyclic voltammetry investigations. Results have shown differences in the oxidation behaviour of the minerals as well as in the SEX interaction with the minerals. The effect of pH was investigated in the case of the Pt minerals and fractional surface coverages were calculated with a view to ultimately correlate these results with flotation behaviour. Proposals are made with respect to the various reactions occurring under the conditions studied

An investigation into the electrochemical interactions between platinum group minerals and sodium ethyl xanthate and sodium diethyl dithiophosphate collectors: Mixed potential study

In the flotation of platinum group minerals (PGMs) occurring in the Platreef ore body, it is often assumed that the interactions between thiol collectors and tellurides of Pt and Pd are similar to those occurring with the equivalent sulphides. In order to gain a greater insight into this assumption a rest(mixed) potential study was conducted to investigate the interactions occurring between two thiol collectors, viz. sodium ethyl xanthate (SEX) and sodium diethyl dithiophosphate (SEDTP), and selected PGMs, viz. moncheite (PtTe2), merenskyite (PdTe2), cooperite (PtS) and vysotskite (PdS) as well as pure platinum and palladium. The results have shown that all these minerals reacted with the collectors in question but that the rest potential of the Pt minerals are more anodic than those of the Pd minerals. Moreover when SEX was used, dixanthogen is more likely to form on PtS than PtTe2 but the reverse is the case for PdTe2 and PdS. In the case of SEDTP it was found that the dithiolate (SEDTP2) did not form on any of the mineral surfaces. The results were compared to those already reported in a previous investigation of the same systems using cyclic voltammetry. The information obtained in these two investigations complement each other and may provide a more fundamental understanding of the role of these collectors in recovering the respective minerals