Review Manganese biomining: A review A.P. Das a , L.B. Sukla b,⇑ , N. Pradhan b , S. Nayak a a Centre of Biotechnology, Siksha O Anusandhan University, Bhubaneswar, India b Institute of Minerals and Materials Technology (CSIR), Bhubaneswar 751 013, India article info Article history: Received 22 March 2011 Received in revised form 6 May 2011 Accepted 8 May 2011 Available online 14 May 2011 Keywords: Manganese biomining Bioleaching Microorganisms abstract Biomining comprises of processing and extraction of metal from their ores and concentrates using micro- bial techniques. Currently this is used by the mining industry to extract copper, uranium and gold from low grade ores but not for low grade manganese ore in industrial scale. The study of microbial genomes, metabolites and regulatory pathways provide novel insights to the metabolism of bioleaching microor- ganisms and their synergistic action during bioleaching operations. This will promote understanding of the universal regulatory responses that the biomining microbial community uses to adapt to their chang- ing environment leading to high metal recovery. Possibility exists of findings ways to imitate the entire process during industrial manganese biomining endeavor. This paper reviews the current status of man- ganese biomining research operations around the world, identifies factors that drive the selection of bio- mining as a processing technology, describes challenges in exploiting these innovations, and concludes with a discussion of Mn biomining’s future. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction In present scenario, the advancement of biomining technology focuses on achieving effective recovery of precious metals by improving the efficiency of bioleaching microorganisms (Xia et al., 2011). This is related to manganese solubilizing activities of manganese-oxidizing microbes and the speciation of intermedi- ate compounds formed during bioleaching processes (Zhou et al., 2009). The demand for manganese ore has increased greater than before considerably due to increase in the manufacture of steel over the years and the growing scarcity of natural resources (Xin et al., 2009, 2011). Beside an efficient manganese production world-wide, a shortage of high grade manganese ore in interna- tional markets still exists for carbon steels. This has led to price gains for both manganese ores and alloys (Doshi, 2007). In order to achieve the projected demand of ferro alloys, there will be huge requirement of manganese for steel making. World’s rapidly grow- ing demand for manganese has made it progressively more impor- tant to develop processes for economical recovery of manganese from low grade manganese ores (Acharya et al., 2003). Recovery of metals from low-grade ores using current pyrometallurgical and hydrometallurgical technologies is prohibitively expensive due to high energy and capital costs. The extensive mining, metal- lurgical and other anthropogenic activities has resulted in the gen- eration of huge amounts of solid mine wastes and mine effluents. The improper management of the metallic effluents has resulted in the mobilization of heavy metals to the surrounding environ- ment, soil contamination, groundwater pollution, and lots of seri- ous environmental problems (Liu et al., 2008). The unprocessed liberation of metals results in a immense loss of precious element like manganese, due to high metal content in it which may be about 4% (w/w) in general or as high as 15% in some cases (Ge et al., 2004). The world yearly utilization of manganese is above 1,500,000 ton and it is intended to rise (Zhang, 2007). According to International Manganese Institute, the resources of manganese dioxide minerals in the European Union (EU) are limited. World- wide reserves of high-grade manganese ores are diminishing at an alarming rate due to the rapid increase in the demand for met- als. The major resource of manganese exists in Russia, Australia, Gabon, Brazil, South Africa, and India. In India high grade manga- nese ore reserves are very limited and mining is being done in Madhya Pradesh, Orissa, Maharashtra and Karnataka states. Man- ganese ore India limited (MOIL) reported that, the projected steel production is expected to touch 60–70 million ton in 2009–2010 and 110 million tons by 2020 according to National Steel Policy. Typically, manganese ore is classified into three grades based on the manganese content of the ore. High grade ores contain more than 44–48% Mn while medium grade and low grade contain 35– 44% and 25–35% Mn respectively (Acharya et al., 2004). Approxi- mately 95% of total production of Mn ore is consumed in steelmak- ing to form ferro-manganese-alloys since no quality steel can be produced without the addition of small amount of manganese (Acharya et al., 2003). In steel it is used for improving the quality 0960-8524/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2011.05.018 ⇑ Corresponding author. Tel.: +91 674 2581635x528; fax: +91 674 2581637. E-mail addresses: suklalb@yahoo.co.in, lbsukla@immt.res.in, lbsukla@rrlbhu.r- es.in (L.B. Sukla). Bioresource Technology 102 (2011) 7381–7387 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech