Kinetic studies on the biological leaching of a zinc sulphide concentrate in two stage continuous stirred tank reactors
A novel reactor configuration was designed and its suitability tested for small scale leaching of concentrates. The salient features of the apparatus were a level controller suitable for agitated and aerated slurries and a sequential timer capable of controlling "the automatic operation of the...
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| Language: | English |
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2010
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| Online Access: | http://hdl.handle.net/2429/22974 |
| Summary: | A novel reactor configuration was designed and its suitability tested for small scale leaching of concentrates. The salient features of the apparatus were a level controller suitable for agitated and aerated slurries and a sequential timer capable of controlling "the automatic operation of the apparatus. Continuous microbiological leaching of a zinc sulphide concentrate in the two stage reactor was conducted in straight through and recycle modes and steady-states were achieved. Kinetic models were developed for straight through and recycle mode operations. The maximum specific growth rate of bacteria attached to the concentrate was found to be 0.019 h⁻¹ giving a generation time of about 52.2 hours. The surface area occupied by the attached bacteria was found to be 0.345 m²/mg or 100 % of the surface area of the residue in tank at steady state. The organism T.ferrooxidans used in this study was shown to exhibit the ability to fix atmospheric nitrogen when ammonium ion concentration in the medium was depleted. It was shown that the amount of leaching could generally be predicted by the application of the shrinking core model of Levenspiel (1972). A design procedure based on this model is given. === Applied Science, Faculty of === Chemical and Biological Engineering, Department of === Graduate |
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