Product Carbon Footprinting and Life Cycle Assessment
MSc Project title A feasibility study of the mineral carbonation of PGM Tailings
(Duration: Jan 2014 to Dec 2015)
Mineral carbonation is a carbon sequestration technology that entails the reaction of CO2 with oxides or silicates of magnesium, calcium or iron to produce stable carbonate compounds. Magnesium-rich tailings from the platinum industry in South Africa have been identified as a potentially viable and attractive feedstock for CO2 sequestration through mineral carbonation.
Preliminary studies have, however, indicated that the inert nature of pyroxene, which is the major magnesium-bearing mineral, is a major limiting factor in terms of the mineral carbonation capacity of these tailings in aqueous systems. Many of the strategies proposed to enhance the dissolution kinetics of silicate minerals, such as the use of elevated temperatures and pressures and chemical additives, as well as pre-treatment through mechanical and thermal activation, are energy intensive and will thus reduce the net CO2 sequestration capacity of the overall mineral carbonation process system. There is growing recognition of the need to develop integrated mineral carbonation processes that reduce input requirements in terms of energy and reagents. However, to date, research and development has focused mainly on the optimisation of extraction and/or carbonation efficiencies, with specific emphasis on the relatively reactive silicate minerals, such as olivine and serpentine.
This project seeks to investigate the viability of using pyroxene-rich PGM tailings for the sequestration of CO2. This involves identifying and evaluating potentially feasible mineral carbonation process systems, with specific emphasis on net carbon neutrality. Furthermore, the effect of leach parameters and pretreatment techniques on the rates and extents of sequesterable cations extraction is investigated.
Ncongwane, M., Broadhurst, J.L., Petersen, J., Bradshaw, S. and Franzidis, J.-P. 2014 A feasibility study of the mineral carbonation of PGM tailings. Poster presented at the at the 32nd annual SAIMM Mineral Processing Conference, 7-8 August, Cape Town.