| Summary: | Thesis (MTech: Chemical Engineering))--Cape Peninsula University of Technology, 2012 === The microbial ferrous-iron oxidation process plays a significant role in bioleaching, providing
ferric-iron (Fe3+) − a strong oxidising agent for the dissolution of most sulphide minerals. An
extensive literature review has shown that several studies have been carried out on microbial
ferrous-iron oxidation, mostly in stirred tank reactors and in conditions close to optimum.
However, limited studies have been carried out on this subject in the context of heap
bioleach situation. Despite the fact a packed column system may be used to represent heap
bioleaching, most of the studies on microbial ferrous-iron oxidation in such systems were
carried out under flooded/fluidised conditions which do not adequately represent solution flow
dynamics in a heap system.
The microbial ferrous-iron oxidation kinetics of Leptospirillum ferriphilum were studied at
substrate loading rates of 0.17 – 0.5 g.L-1h
-1 (dilution rates 0.033 – 0.1 h-1). The study was
conducted in a packed column with a view to investigating the kinetics in a system which
simulates the solution flow dynamics of a typical heap bioleach operation. Glass marbles, 15
mm in diameter, were used as reactor packing. The microbial oxidation kinetics were
investigated in a continuous mode at the desired loading rates. The pH of the bioreactor was
maintained at pH 1.45 ± 0.05 and the aeration at 15 mL.s-1. Both Monod and Hansford
models were used to describe the biooxidation kinetics.
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