Effect of Silver Ions on Bacterial Leaching of Flotation Concentrate of Conner-Nickel Sulfide Ores

Abstract

The bacterial leaching of flotation concentrate of copper-nickel sulfide ores (Jinchuan mine in China) containing chalcopyrite and pentlandite was studied using Thiobacillus ferrooxidans. About 75 percent of nickel in the concentrate was dissolved after 42 days of bacterial leaching, but the extraction of copper was only 14 percent.
In order to enhance copper extraction, effect of silver ions on the bacterial leaching of copper-nickel flotation concentrate was investigated. Silver ions accelerated the leaching of chalcopyrite by Thiobacillus ferrooxidans. The leaching rate of copper increased as initial silver concentration was increased up to 38mg/l. A 59 percent of copper in the concentrate was dissolved after 10 days of bacterial leaching at initial silver concentration of 38mg/l. However, the leaching rate of nickel decreased as initial silver concentration was increased. The reason is that silver ions hinder the leaching of pentlandite with ferric ions.