Investigation of the potential for mineral carbonation of PGM tailings in South Africa

Increasing atmospheric CO2 concentration is currently of considerable concern in terms of global warming. A possible technology that can contribute to the reduction of CO2 emissions is its sequestration by mineral carbonation. In this study, tailings from several different platinum mines in South Africa will be mineralogically characterised and their potential for mineral carbonation reviewed. Mg and Ca-rich minerals (plagioclase, olivine, orthopyroxene, clinopyroxene) present in the tailings are good candidates for mineral carbonation, which mimics natural weathering processes in which these minerals react with gaseous CO2 to form Ca or Mg carbonates. Since the reaction is influenced by particle surface area, the ultra fine grained nature of the PGM tailings provides another reason for the promise of PGM tailings for mineral carbonation. A preliminary ranking of the tailings samples and their efficacy for mineral carbonation has been developed according to whether the samples showed harzburgtic (e.g. Northam Platinum mine), pyroxenetic (e.g. BRPM) or noritic mineral assemblages. This information and understanding will assist in identifying opportunities and guiding the development of engineered facilities for the sequestration of CO2 by means of mineral carbonation.

► Established a ranking scheme for carbonation of tailings from PGM operations.
► Determined the theoretical carbonation capacity of wastes from the SA PGM industry.
► Provided a foundation for further studies on mineral carbonation of PGM tailings.