Biomining

Biomining is an approach to the extraction of desired minerals from ores. Microorganisms are used to leach out the minerals, rather than the traditional methods of extreme heat or toxic chemicals, which have a deleterious effect on the environment.

The development of industrial mineral processing has been established now in several countries including South Africa, Brazil and Australia. Iron-and sulfur-oxidizing microorganisms are used to release occluded copper, gold and uranium from mineral sulfides. Most industrial plants for biooxidation of gold-bearing concentrates have been operated at 40 °C with mixed cultures of mesophilic bacteria of the genera Acidithiobacillus or Leptospirillum ferrooxidans. In subsequent studies the dissimulatory iron-reducing archaea Pyrococcus furiosus and Pyrobaculum islandicum were shown to reduce gold chloride to insoluble gold.

Using Bacteria such as Acidithiobacillus ferrooxidans to leach copper from mine tailings has improved recovery rates and reduced operating costs. Moreover, it permits extraction from low grade ores - an important consideration in the face of the depletion of high grade ores.

The potential applications of biotechnology to mining and processing are countless. Some examples of past projects in biotechnology include a biologically assisted in situ mining program, biodegradation methods, passive bioremediation of acid rock drainage, and bioleaching of ores and concentrates. This research often results in technology implementation for greater efficiency and productivity or novel solutions to complex problems. Additional capabilities include the bioleaching of metals from sulfide materials, phosphate ore bioprocessing, and the bioconcentration of metals from solutions. One project recently under investigation is the use of biological methods for the reduction of sulfur in coal-cleaning applications. From in situ mining to mineral processing and treatment technology, biotechnology provides innovative and cost-effective industry solutions.

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