Bacterial dissolution of pyrite by Thiobacillus ferrooxidans |
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| Authors: | Y. Konishi S. Asai H. Katoh |
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| Affiliation: | (1) Department of Chemical Engineering, University of Osaka Prefecture, Sakai, 591 Osaka, Japan |
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| Abstract: | The kinetics of the dissolution of pure pyrite (FeS2) particles by Thiobacillus ferrooxidans were studied both theoretically and experimentally. Adsorption and dissolution experiments were carried out at 30 °C and pH=2, by using a batch reactor. The adsorption process of T. ferrooxidans to pyrite surface was rapid in comparison with the bacterial dissolution process. The experimental results for the adsorption equilibrium were well correlated by the Langmuir type isotherm. The growth rate of adsorbed bacteria was found to be proportional to the product of the number of adsorbed cells and the fraction of solid surface unoccupied by cells. A new kinetic model for the bacterial dissolution was presented, and shown to correlate well with the experimental data for the rate of bacterial dissolution and for the time variation in the number of cells in the liquid phase. The specific growth rate of adsorbed bacteria was also evaluated.List of Symbols f weight fraction of iron in pyrite - KA m3/cells equilibrium constant for cell adsorption - RA cells/d m3-mixture growth rate of bacteria adsorbed on solid surface - RL cells/d m3-mixture growth rate of free bacteria in the liquid phase - t d time - V m3 volume of solid-liquid mixture - W kg weight of pyrite - W0 kg initial weight of pyrite - XA cells/kg-solid number of adsorbed cells on solid surface - XAm cells/kg-solid maximum adsorption capacity - XL cells/m3-liquid number of free cells existing in the liquid phase - XT cells/m3-mixture total number of cells - XTO cells/m3 initial total number of cells - YA cells/kg-FeS2 growth yield of adsorbed bacteria - YL cells/kg-Fe2+ growth yield of free bacteria - [Fe]T kg/m3-liquid concentration of total iron in the liquid phase -  fraction of pyrite dissolved -  V fraction of adsorption sites unoccupied by cells -  A d–1 specific growth rate of adsorbed bacteria - L d–1 specific growth rate of free bacteria -  volume fraction of solid particles in solid-liquid mixture |
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