Environmental chemistry and mineralogy of particulate air matter around Selebi Phikwe nickel–copper plant, Botswana

This study aimed at chemically and mineralogically characterizing whole particulate air matter (PAM) occurring at the Selebi Phikwe nickel–copper (Ni–Cu) area in Botswana, and postulating its possible environmental implications. Heavy metals concentrations in PAM samples around the Selebi Phikwe Ni–Cu plant were determined by atomic absorption spectrometry and the mineral phases identified by X-ray powder diffraction technique. The particles consisted of quartz, pyrrhotite, chalcopyrite, albite and djurleite. Concentration levels of heavy metals contained in PAM samples could be related to mineral phases present. Quite significantly is the occurrence of djurleite, which has not been found in both the orebody and surrounding soils. Djurleite polymorphs formed from secondary mineralization of chalcocite and the gases H2S and SO2 released from concentration/smelting processes. Possible environmental chemistry of the whole PAM based on its mineralogy at Selebi Phikwe area is discussed.