STUDIES IN THE BACTERIAL LEACHING OF NICKEL ORES

Abstract

The applicability of bacterial leach technique in the extraction of nickel from naturally occurring nickel minerals and from sulfide and silicate nickel ores has been investigated. The nickel minerals gerstorffite, niccolite, and pentlandite could be leached with Thiobacillus thiooxidans whereas silicate nickel ores seemed to be inefficient to leaching with Thiobacillus. Within 100 days less than 1 % of the nickel was extracted from silicate ores. Sulfide nickel ores have been leached with Th. ferrooxidans and Th. thiooxidans. In air-lift-percolators within 100 days 17 % of the nickel were extracted using pure cultures of Th. thiooxidans, but only 5.6 % were recovered after leaching with Th. ferrooxidans. Within 30 days 38 %, 66 %,and 70 % of the nickel were extracted from ground material (Harzburger Gabbro) by submerged fermentation in shaking Erlenmeyer flasks adding pure cultures of Th. thiooxidans, Th. ferrooxidans and a mixed culture of both strains, respectively, to the culture medium.