Bioleaching of copper from metal concentrates of waste printed circuit boards by a newly isolated Acidithiobacillus ferrooxidans strain Z1

The goal of this study is to determine the potential of Acidithiobacillus ferrooxidans strain Z1 in bioleaching of metal concentrates of waste printed circuit boards (PCBs). The influences of initial pH, initial Fe(II) concentration, metal concentrates dosage, inoculation quantity and particle size on the bioleaching process were investigated and optimum conditions were determined. The results showed that 92.57 % copper leaching efficiency was achieved within 78 h in a two-step process, and 85.24 % aluminum and 95.18 % zinc were leached out after 183 h under the optimum conditions of initial pH 2.25, initial Fe(II) 9 g/L, metal concentrates dosage 12 g/L, inoculation quantity 10 % and particle size 0.178-0.250 mm. It demonstrated that metals could be efficiently leached from metal concentrates by Acidithiobacillus ferrooxidans Z1 and the bioleaching period was reduced 81-78 h. Therefore, the strain Acidithiobacillus ferrooxidans Z1 could be suggested as a potential strain to bioleach metals from metal concentrates of waste PCBs.