Pre-treatment of a Hydrocarbon Contaminated Platinum group Minerals Mine Sludge using a Non-ionic Surfactant

In South Africa, the Merensky, Upper Group 2 (UG-2), and Platreef are the three primary platinum group mineral (PGM) reefs found in the Bushveld Igneous Complex (BIC). PGM output is now mostly sourced from Platreef and UG-2 reefs. Most of the PGM mines have become highly mechanised, leading to the production of mine sludge contaminated with hydrocarbons. This study investigated the removal of the hydrocarbons using a non-ionic surfactant in preparation for the flotation process. The contaminated mine sludge was characterised for hydrocarbon content, mineralogical and elemental composition. Response Surface Methodology-Box-Behnken (RSM-BBD) design of experiments was used to design the washing experimental runs. The results revealed that the sample contained 9.32g/t of total four elements (Pt, Pd, Rh and Au) with most of the PGMs found in the sulphide form. Chromite and quartz are the common gangue minerals that were found in the sample. Fourier transform infrared spectroscopy showed that there were hydrocarbons present in the sample. The washing experiments showed that Triston-100 (TX-100) can be used to remove hydrocarbons from the contaminated PGMs mine sludge. The optimum washing conditions with a hydrocarbon removal efficiency of 91.86% were found to be 12.25 g/kg surfactant concentration, 150 minutes of washing time and a pH of 12.