Effect of Cu2+ ions on bioleaching of marmatite
(Key Laboratory of Biometallurgy of Ministry of Education,
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
Abstract: The effect of Cu2+ ions on bioleaching of marmatite was investigated through shake leaching experiments. The bacteria inoculated are a mixed culture of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Lepthospirillum ferrooxidans. The results show that zinc is selectively leached, and the addition of appropriate content of Cu2+ ions has positive effect on the bioleaching of marmatite. SEM and EDX analyses of the leaching residue reveal that a product layer composed of iron sulfide, elemental sulfur and jarosite forms on the mineral surface. The biooxidation of elemental sulfur is catalyzed by the Cu2+ ions, which eliminate the barrier to bioleaching of marmatite and keep low pH value. With the addition of 0.5 g/L Cu2+ ions, the maximum zinc extraction rate reaches 73% after 23 d at the temperature of 30 ℃ with the pulp density of 10%, while that of iron is only about 10%.
Key words: Cu2+ ions; marmatite; bioleaching; zinc