1995 Volume 111 Issue 13 Pages 943-948
The effect of surfactant addition on bacterial leaching of chalcopyrite by Thiobacillus ferrooxidans was investigated with polyoxyethylene sorbitan monolaurate (Tween20) as a surfactant. Bacterial leaching experiments were carried out without nutrient mineral salts such as ammonium sulfate to avoid the complication of leaching behavior with cell growth. Without the surfactant, most cells adhered to the mineral surface and soluble iron was dominantly present in ferrous form. The surfactant depressed the cell adhesion to the mineral surface and the number of cells in the liquid phase increased with increasing addition. When adding 20 to 50g/m3 of the surfactant, the cells in the liquid phase rapidly oxidized ferrous ions to form ferric ions and chalcopyrite was chemically oxidized by the ferric ions, as a result the amount of extracted copper increased markedly. However, the excessive addition depressed the bacterial ferrous oxidation and the chemical leaching of chalcopyrite with ferric ions, and decreased copper extraction.
