An investigation into the effect of solid particulate phase on the bioleaching performance of Sulfolobus metallicus

Master Thesis


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University of Cape Town

Gold-bearing refractory sulphidic ores require a pretreatment process before extraction of the valuable metal, may be carried out. Bioleaching of the mineral may be used as pretreatment. Further mineral bioleaching may be used to liberate base metals such as copper from refractory sulphidic ores. The microorganisms used in the high intensity tank-based commercial biohydrometallurgy processes are mainly mesophiles, although moderate thermophiles are currently used at Youanmi Mine in Australia (Brierley, 1997). Extreme thermophiles have been found to exhibit enhanced oxidation kinetics in terms of rate of reaction and extent of solubilisation (Duarte et al, 1993; Norris and Barr, 1988; Konishi et al., 1995). However, these thermophiles appear to be sensitive to hydrodynamic conditions (Clark and Norris, 1996) and the presence of solids (Le Roux and Wakerley, 1988; Nemati and Harrison, 2000). An understanding of this sensitivity would be useful in developing systems to utilise extreme thermophiles in commercial biohydrometallurgy processes. The main objective of this study was to determine the effect of the solid particulate phase on the bioleaching performance of the extreme thermophile Sulfolobus metallicus. The hypothesis of the thesis was as follows: Archae involved in bioleaching are susceptible to damage in agitated aerated vessels, especially with increasing pulp density.

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