Biohydrometallurgy

Biohydrometallurgy is a subfield of hydrometallurgy and biotechnology.

Definitions

1. Interdisciplinary field involving processes that:
   1. are driven by microbes - bio.
   2. mainly take place in aqueous environment - hydro
   3. deals with metal production and treatment of metal containing materials and solutions - metallurgy
2. “Biohydrometallurgy may be defined, in very general terms, as that branch of biotechnology dealing with the study and application of the economic potential of the interactions between the microbial world and the mineral kingdom. It concerns, thus, all those engaged, directly or indirectly, in the exploitation of mineral resources and in environmental protection: geologists, economic geologists, mining engineers, metallurgists, hydrometallurgists, chemists and chemical engineers. In addition to these specialists, there are the microbiologists whose work is indispensable in the design, implementation and running of biohydrometallurgical processes.” (Rossi, 1990)^[1]
3. Biohydrometallurgy can be defined as the field of applications resulting from the control of natural (biochemical) processes of interactions between microbes and minerals to recover valuable metals.

Background

Metal-bearing materials are conventionally processed by abiotic physical and chemical treatments. But biohydrometallurgy makes use of the fact that microbes are affecting mineral transformations. Interactions between microbes and minerals may amplify chemical transformations and transport phenomena. Microbes regulating biologically-amplified transformations are identified and investigated. Biological phenomena may be adapted to become new methods to bioprocess minerals.

All metals are potentially relevant to biohydrometallurgical techniques. Copper and gold are the metals that are industrially produced from ores at significant rates by bioleaching and biooxidation. Metals are also recovered from metal rich effluents, mainly in order to get clean water, usually with the help from sulfate reducing bacteria

Historically, biohydrometallurgy was passively used for centuries or more to recover copper without much knowledge of the exact nature of the phenomenological processes. As a practice on an industrial scale, it has seen constant development in the last 40 years. The biochemical processes have been subject to investigations for the last 20 years.

Biohydrometallurgy deals with bioleaching (and biooxidation) as well as with bioimmobilization.

Biohydrometallurgy and supporting technologies

• Processing of minerals in aqueous solutions. For example:
  • Biomining - metal recovery in large-scale operations. In commercial use.
  • Biobeneficiation. Not in commercial use.
  • Wastewater treatment for removal of metals and sulfate. In commercial use.
  • Coal desulfurisation by removal of sulfide minerals from coal to reduce emissions of sulfur dioxide. Not in commercial use.
• Bio-sensoring - to use microbes to transform solubilized metals so the metals can be detected.