Abstract
This work investigated the effects of Fe3+, H+ and adsorbed leaching bacteria on the bioleaching of pentlandite. Collectively, an integrated model for the oxidation and decomposition of pentlandite was built to describe the behaviors of different components in a bioleaching system. Proton ions and ferric ions could promote the break and oxidation of Ni-S and Fe-S bonds. The iron-oxidizing microorganisms could regenerate ferric ions and maintain a high Eh value. The sulfur-oxidizing microorganisms showed significant importance in the oxidation of polysulfide and elemental sulfur. The atoms in pentlandite show different modification pathways during the bioleaching process: iron transformed through a (Ni,Fe)9S8 → Fe2+ → Fe3+ → KFe3(SO4)2(OH)6 pathway; nickel experienced a transformation of (Ni,Fe)9S8 → NiS → Ni2+; sulfur modified through the pathway of S2−/S22− → Sn2− → S0 → SO32− → SO42−. During bioleaching, a sulfur-rich layer and jarosite layer formed on the mineral surface, and the rise of pH value accelerated the process. However, no evidence for the inhibition of the layers was shown in the bioleaching of pentlandite at pH 3.00. This study provides a novel method for the extraction of nickel from pentlandite by bioleaching at elevated pH values.
Highlights
As an indispensable raw metal material, nickel plays an important role in industry production.The industrial-scale application of nickel metal began over a hundred years ago, supporting the social development
This study provides a novel method for the extraction of nickel from pentlandite by bioleaching at elevated pH values
This paper investigated the efforts of major components (Fe3+, H+, leaching bacteria) on the oxidation and decomposition of pentlandite
Summary
As an indispensable raw metal material, nickel plays an important role in industry production. The industrial-scale application of nickel metal began over a hundred years ago, supporting the social development. Economic nickel resource deposits are land-based, with about 40%. Sulfide ore used to be the major resource for nickel, with a mature recovery technology of flotation, smelting, and electrowinning. Hydrometallurgy has been employed in the treatment of nickel laterite to avoid carbon emission and air pollution. Application of bio-hydrometallurgy has been extended to the extraction of nickel from sulfide ore. Several operational practices [1] of bio-heap leaching suggested that bio-hydrometallurgy could be a feasible technology for the recovery of nickel from low-grade sulfide ores.
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