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A life-cycle-based review of sulfur dioxide abatement installations in the South African platinum group metal sector

Munyongani, V., von Blottnitz, H., Broadhurst, J. L.
Sustainability science 2017 v.12 no.5 pp. 769-784
acidification, byproducts, decision making, energy, environmental assessment, environmental impact, flue gas, furnaces, industry, interviews, life cycle assessment, minerals, platinum, pollution control, sulfur dioxide, sulfuric acid, South Africa
In the late 2000s, several South African platinum producers retrofitted sulfur dioxide abatement technologies to smelters in the Rustenburg area. While such end-of-pipe technologies can reduce local environmental impacts, they may also increase impacts associated material and energy use. Two methodologies were fused to study how these retrofits have shifted environmental burdens, and whether such knowledge would have been useful to design decision-makers. A life cycle assessment was carried out to determine the environmental impacts associated with the key design choices of these smelter and furnace flue gas SO₂ abatement technologies, viz. technology choice and the fractional recovery of SO₂. The two technology options used by industries and investigated were i) concentrated dual-alkali srubbing and ii) a srubber feeding an acid plant. The results show that the concentrated dual-alkali process has, overall, higher environmental impacts than the scrubber with acid plant. Notably, for the former, all environmental impacts (except acidification) increase with increasing SO₂ recovery, whereas for the latter some impacts reduce with increasing recovery due to the by-product sulfuric acid that replaces acid otherwise produced. Subsequently, the results of the LCA were combined with insights from expert interviews to explore design decision-making in the minerals industry, and whether incorporating LCA in formal environmental assessment processes would be of any value to the minerals industry. Expert interviews revealed that incorporating LCA could enable the quantification of impacts for the different technology options, and help justify the chosen options. We argue that normalised results would enable more meaningful interpretation of LCA to further assist such decision-making processes.