Manganese Biomining from Manganese-Bearing Industrial Wastes of Georgia

Abstract

In Georgia, the amount of manganese-bearing industrial wastes is estimated at 15 million tons, of which over 10 million tons are mine wastes of Chiatura deposit. The resource potential of these technogenic formations makes 1.5 million tons of pure manganese. Every year the volume of these wastes increases by one mln t on average. An economic loss from non-utilization of this valuable manganese stock is great. Also great is an environmental damage. Analysis of a possibility of recycling manganese-bearing waste indicates the prospects of using environmentally safe and profitable biotechnological processes of utilizing this technogenic raw material. For intensifying the known methods of manganese biomining, the authors have developed a new technological leaching scheme, which, at the first stage, for processing the stock provides for its desilicalization by silicate bacteria B.mucilaginosus. The result of this stage is an increase in the content of manganese in the raw material by 25–30%, with an increase in the cumulative response surface for applying bacteria A.ferrooxidans at the next stage. One of the main distinctive features of the proposed scheme is also integration of the manganese leaching process with the copper and zinc recovery process. The advantage of this combined process consists in the application of the afterproduct of leaching of these nonferrous metals—a ferrous (II) sulfate compound for speeding up the manganese extraction, and, vice versa, in the application of ferric (III) sulfate produced upon manganese leaching to activate copper and zinc extraction. The advantage of the use of the bicultural solution A.ferrooxidans-R.phaseoli in manganese leaching instead of the monoculture one (A.ferrooxidans) is also substantiated. As a result of practical realization of the proposed technical novelties, the manganese extracting degree can be increased to 98–99%, while the length of leaching can be reduced to 14–21 days. The commercial exploitation of the proposed combined technological scheme of manganese biomining will increase the resource base of Georgian manganese, for it will create a new possibility for recycling environmentally harmful wastes and cut-off grade ores of Chiatura deposit.