This Small Business Innovation Research Phase I project will advance a novel anaerobic bioprocess for liberating precious metals from metal-sulfide ores. As near-surface, oxidized ore reserves are depleted, gold producers are increasingly faced with the challenge of extracting gold and other metal values from sulfidic ores that are refractory to conventional processing techniques. This often puts mining concerns at odds with forest and agricultural interests. At present, when the demand is high for more cost effective and environmentally-friendly ore processing options, bioprocessing as currently implemented is considered impractical for large-scale applications for three reasons: (1) slurry cooling requirements on the order of megawatts, (2) difficulties in delivering oxygen into slurries at very high rates, and (3) excessive neutralization of reagent costs and sludge production. This research will employ the tools of the bioprocess engineering discipline to overcome these issues. It will encourage widespread adoption of a bioprocess that is more energy efficient and environmentally acceptable than the alternatives, roasting and autoclaving, which sign)ficantly impact air and water resources. Based on the thermodynamics and microbiology of each step in the bioprocess, kinetic and stoichiometric models will be developed. An experimental apparatus will be constructed and proof-of-concept experiments will be conducted.Applications:International gold producers spend over $10 billion annually to process gold ores. While the industry has traditionally been slow to apply new technologies such as bioprocessing, recent interest to biotechnologies has been sparked by a sign)ficant change in the mineralogy of the ores being processed and severe cost and environmental pressures. This innovative anaerobic bioprocess for liberating gold and silver from sulfidic ores will sign)ficantly reduce the costs and the environmental risks of conventional big-oxidation, making it an appealing alternative to the mining industry.
