The effects of pH, anions, cations and ionic strength on tetrathionate oxidation by Acidithiobacillus caldus
Acidithiobacillus (At. ) caldus is a sulfur-oxidising acidophilic bacterium found in managed heaps of lowgrade ores. The heap habitat is heterogeneous and variable due to changing mineralogy, increasing concentrations of solutes in recycled liquors and climatic influences. The intent of this study was to examine the effects of water quality parameters relevant to heap leach systems on tetrathionate oxidation by At. caldus. It was found that At. caldus was sensitive to elevated pH as might be found at depth in heaps of acid-consuming ores, but nevertheless continued to oxidise tetrathionate slowly even at pH 7. 5 with concomitant production of new cells. Increased concentrations of selected inorganic salts in the range 0-40 g/L (ionic strength range 0. 02 - 0. 86 M) generally caused longer delays prior to tetrathionate oxidation by At. caldus. Specific growth rates during the period of rapid tetrathionate oxidation decreased with increased salt concentrations. Total increases in cell numbers generated during oxidation of the available tetrathionate varied considerably, even in the control tests without additive. In general, cell numbers decreased with increased salts concentrations, consistent with increased energy requirements for cell maintenance. Two results were unexpected; the strong inhibition of tetrathionate oxidation with potassium sulfate addition, and the acceleration of tetrathionate oxidation with ferric sulfate addition in the presence but not in the absence of At. caldus. The data generated in this study add to our knowledge of the responses of At. caldus to solution compositions that might be encountered in heap leaching systems. Through comparison with other studies, the data obtained also show that responses are sometimes species specific. Thus it may be concluded that, for a holistic understanding of microbial behaviour in heaps, similar studies should be undertaken for those microorganisms thought to play important roles in iron or sulfur oxidation.
Acidithiobacillus caldus tetrathionate water quality heap leaching
G. J.Zhang D. W.Shiers H. R. Watling
Institute of Process Engineering, Chinese Academy of Sciences, PO Box 353, 100190, Beijing, China A. A. J. Parker Cooperative Research Centre for Integrated Hydrometallurgy Solutions, CSIRO Minerals Do
国际会议
The 19th International Biohydrometallurgy Symposium(第19届国际生物湿法冶金大会 IBS2011)
长沙
英文
220-228
2011-09-18（万方平台首次上网日期，不代表论文的发表时间）