New Dimensions of Microbial Technique: Coal Processing and Desulfurization, Separation of Metals and Environment Protection

Abstract

Microbiological methods are now being exploited in many non-conventional areas, including mineral processing, leaching/separation of metals, coal desulfurization and for environmental protection. Generally, the prevalent methods for extraction of metals from mine refuse and low-grade ores are not only costly but also not environment-friendly. However, microbial techniques can be gainfully exploited on a large scale to obtain metals and non-metals from the poor quality ores/minerals and mine refuse, as they are much cheaper compared to the conventional chemical methods. Some examples are: extraction of copper metal from sulphur-containing copper minerals and isolation of manganese from manganese ore by means of bioleaching. Of late, microbiological methods are finding wide applications in the desulfurization of high sulfur coals, as these methods are found to be quite effective and eco- friendly. A number of valuable substances can also be produced from coal exploiting the effectiveness of various microorganisms, e.g. , microbial conversion of lignite to humic acid ; production of methane, methanol , ethanol by microbial processing of coal, etc. Besides, microbes also play very important role and are being effectively used for the conversion of unavailable forms of several nutrients such as phosphorus, sulfur, copper, iron, in available form in the soil , such that microbial techniques are now being well targeted to convert unproductive lands into fertile ones. Environmental safety is being ensured by effectively purifying and detoxifying the organic and inorganic hazardous wastes from medicine industry, for which D.R.C.C. bacteria of <i>Cocobacilli </i>family, isolated from soil, have been found to be very efficient and efficacious.<br><br> In the paper, diverse and multi - facetd applications of microbial techniques in different areas such as mineral processing, metal extraction, coal beneficiation (desulphurization and demine ralization), environmental protection are highlighted.