Abstract
The aim of this study is to investigate the potential of newly isolated strain Leptospirillum (L.) ferriphilum CC for bioleaching of pyrite and chalcopyrite in pure or mixed culture with other iron- and/or sulfur-oxidizing bacteria. In this paper, kinetics of ferrous iron (Fe2+) oxidation by newly isolated strain Leptospirillum (L.) ferriphilum CC was studied. The effect of initial Fe2+ in the concentration range of 50–400 mM on bacterial growth and iron oxidation was studied. It was shown that microbial Fe2+ oxidation was competitively inhibited by Fe3+. The influence of copper, zinc, nickel and cobalt ions on the oxidation of Fe2+ by L. ferriphilum CC was also studied. Minimal inhibitory concentrations (MIC) for each metal ion were determined. The toxicity of the ions was found to be as follows: Co > Zn > Ni > Cu. The comparison of iron oxidation kinetic parameters of L. ferriphilum CC with other strains of L. ferriphilum indicates the high potential of strain L. ferriphilum CC for biogenic regeneration of concentrated ferric iron (Fe3+) in bioleaching processes of ores and ore concentrates. Bioleaching tests indicated that the newly isolated L. ferriphilum CC can be a prospective strain for the bioleaching of sulfide minerals in pure culture or in association with other iron- and/or sulfur-oxidizing bacteria.
Highlights
Bioleaching is an environmentally friendly technology that is increasingly applied worldwide for processing of mineral raw materials and for recovery of copper, uranium and gold from low-grade ores and waste materials [1]
Metal sulfide is oxidized by Fe3+ and the role of microorganisms refers to the oxidation of Fe2+ and regeneration of Fe3+
L. ferriphilum CC is deposited at the Microbial Depository Center (MDC) of the SPC “Armbiotechnology” of National
Summary
Bioleaching is an environmentally friendly technology that is increasingly applied worldwide for processing of mineral raw materials and for recovery of copper, uranium and gold from low-grade ores and waste materials [1]. Bioleaching technology converts an insoluble valuable metal sulfide into a soluble form by means of microorganisms or destroys the lattice of the sulfide minerals to make the gold available for further extraction by cyanidation [2,3]. (mainly Leptospirillum ferriphilum) are the dominant iron-oxidizing bacteria in gold-bearing arsenopyrite (FeAsS). It is considered that the main mechanism of microbial attack on the metal sulfides is an indirect contact mechanism. Metal sulfide is oxidized by Fe3+ and the role of microorganisms refers to the oxidation of Fe2+ and regeneration of Fe3+.
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