Characterization of Hydrocarbons Contaminated Platinum Group Metals Mine Sludge from the Bushveld Complex

- Mechanized mining methods adopted in platinum-group elements (PGE) industry leads to mobile machinery leakages which result in mine sludge contamination by hydrocarbons. This paper aims at investigating the mineralogical characteristics of the contaminated mine sludge in comparison to the pristine ore. Two types of samples were used in the study were pristine PGE ore and contaminated PGE mine sludge. The samples were analysed using FTIR, XRF, XRD, SEM-EDS, Fire assaying, ICP-OES and Malvern PSD analyser for elemental composition, mineral composition, particle size distribution and the presence of hydrocarbon functional groups. FTIR results indicated the presence of a single C-H bonds in the contaminated mine sludge, which is the hydrocarbons functional group and pristine PGE ore was found to be free from an indication of such contaminants. The fire assaying results revealed that the mine sludge contained a total of 9.32g/t 4E (5.68 ppm Pt, 2.95ppm Pd, 0.6ppm Rh and 0.09ppm Au) and the pristine ore 4.74g/t 4E (2.64ppm Pt, 1.63ppm Pd, 0.42ppm Rh and 0.05ppm Au). SEM-EDS further confirmed that the sludge is indeed richer in PGE than pristine PGE ore. Mineral phases identified by XRD included millerite, chalcocite, aluminium oxide, chalcopyrite, pyrite, pyrrhotite, pentlandite, anorthite, enstatite and magnesium chromite and they were common to both samples. Particle size analysis revealed that the hydrocarbon contaminated mine sludge and the pristine ore had a P80 of 169 and 252µm respectively. Both samples had approximately 4% of fines (<10 µm). Remedial of hydrocarbon contaminants would lead to high grade PGE recovery.