Papers by Author: James A. Brierley

Abstract: The importance of comprehensive laboratory evaluation for development of an ore body to commercial processing using biohydrometallurgy cannot be understated. Laboratory evaluation for a biohydrometallurgical process must include the microbiological component and definition of operating parameters for the engineers to design the commercial plant. Failure to meet commercial production at a mine site can be a consequence of incomplete understanding of biohydrometallurgical technologies for processing a specific ore. One example is the inability of a copper bioleach process to meet the design criteria in part because of lack of sufficient testing to demonstrate the ramifications of fluoride toxicity to the microbial component of the bioleach process. Laboratory research has demonstrated toxicity of low levels of fluoride to Acidithiobacillus species. However, laboratory determined toxicity values are not always relevant to field conditions at commercial bioleach operations. This is the case with fluoride toxicity where complexing reactions increase the amount of fluoride required for toxicity. Consequently, the toxic fluoride concentrations at field sites can be significantly higher than toxic levels reported in the laboratory, but still achieve concentration inhibitory for the microorganisms.

Abstract: My perceptions of the biohydrometallurgical field span four decades and stem from being a professional microbiologist conducting academic research and research for process development and applications. My experiences have given me an appreciation for knowledge gained through fundamental research and the transfer of this knowledge to development of commercial scale applications of microbial processes. The symposia series for international activities in biohydrometallurgy has been a major factor in advancing knowledge and applications for microbial bioleach systems. The first international biohydrometallurgy meeting was held in Braunschweig, Germany in 1977. This was the predecessor for the International Biohydrometallurgy Symposia. As evident from the Symposia, advances in development and applications of biohydrometallurgy technologies follow an evolutionary, rather than revolutionary progression from demonstration of knowledge at the laboratory scale to engineering commercial plants.