An Overview: Application of Microorganisms in Bio-Mining of Metals (Review Article)

Abstract

Biomining of copper from ores was started during ancient era without even knowing the role of microorganisms in the process. The ever-increasing demand of metals, declination of natural resources, huge reserves of low-grade metallic ores and generation of massive amount of metallic wastes from mining and beneficiation process has led to the evolution and commercial scale adoption of biomining. The ability of microorganisms to bioamine metals depends on redox reactions, organic or inorganic acid formation and the release of complexing agents. Redox reaction is the key step of biomining process which is based either on direct or indirect bioleaching. The main difference between the two mechanisms is the direct contact between the microorganisms and the reduced minerals. Apart from the economic benefits, biomining also reduces the problem of acid mine drainage (AMD). Biomining is successfully utilized in metal recovery from low grade ores, mine tailings, mine wastes, municipal solid waste dump sites, legacy wastes, incinerator ash, E-wastes and, shales and tars etc. In this way, biomining inhibits the release of heavy metals from various types of wastes to the environment and release of toxic gases from the municipal solid waste dump sites and legacy wastes.