Present and future commercial applications of biohydrometallurgy

Modern commercial application of biohydrometallurgy for processing ores bec ame reality in the 1950s with the advent of copper bioleaching by what was Kennecott Copper Corporation. Early application entailed dump leaching of l ow-grade, low-value, run-of-mine material. Dump bioleaching has evolved int o a commercially accepted option for copper bioheap leaching of higher-grad e, higher value ores. This commercial practice is exemplified at the Quebra da Blanca Mine operation and others. Paradoxically, application of biohydro metallurgy in the pretreatment of refractory gold ores began with processin g high value concentrates, using biooxidation-tank processes and was follow ed by extension to processing low-grade, lower value ores in heaps. Even wi th the current success of biohydrometallurgical applications in the mining industry, the real potential of biotechnology in mining remains to be reali zed. As confidence in commercial bioprocessing grows and experience extends the application's knowledge base, innovations and new commercial practices will emerge. Near term future commercial applications will likely remain f ocused on recoveries of copper and gold. Recent technical advances show tha t very refractory chalcopyrite can be successfully bioleached. Processes fo r copper recovery from this mineral will include both heap and stirred-tank reactor systems. Next generation technologies for pretreatment of refracto ry gold ores will be based on use of thermophilic bacteria for sulfide oxid ation. For biohydrometallurgy to commercially advance, the microbiologist m ust work cooperatively with the practitioners of the technology for mutual understanding of operational limitations and practical constraints affectin g the microbiological component.