Chapter 12 - Mixed culture bioleaching: an insight into manganese biomining process and efficacy

Abstract

Mixed culture bioleaching is the process of metal recovery from low-grade ores with the help of a microbial consortium. Bacterial and fungal groups that are involved in the mixed culture get adapted to the extreme column environment; in some cases, they release extracellular polymeric substances. With the increasing demand for manganese by industry new methods for manganese recovery have been under development by researchers. Conventional leaching methods involve strong acids and are quite hazardous to the environment. Recovery of metals by biomining with the help of microbes is considered to be one of the superior and greener options than the current pyrometallurgical techniques. Bioleaching is the extraction process which is promoted for the oxidation of sulfur with high sulfate concentration and which consists of much better oxidation–reduction ability. Bioleaching efficiencies during manganese extraction were found to be 75%–90%. Thiobacilli is one of the most significant groups of microorganisms associated with the bioleaching process. During bioleaching microbial colony succession also takes place which leads to a change in their abundance. A mixed culture is more efficient and rapid than a pure culture. Manganese bioleaching has the main goal of recovering metal from low-grade ore with the help of microbes by undergoing a mixed culture process. Manganese value bearing less than 40% of manganese ore is retrieved from the earth and a smaller amount is being processed whole over worldwide... Reserves of manganese are shrinking at an alarming rate and recovery of metals from untreated mining wastes through bioleaching turned out to be a greener initiative than other pyro metallurgical techniques. This technology seems to be beneficial in terms of the growing challenge of metal extraction from low-grade ores.