direct and indirect bio-leaching of co and ni from an iron-rich laterite ore using delftia acidovorans and acidithiobacillus ferrooxidans

In this research work, the bio-leaching of co and ni from an iron-rich laterite ore is assessed using the acidophilic heterotrophic (delftia acidovorans) and autotrophic (acidithiobacillus ferrooxidans) bacteria. the metabolic products of the acidophilic bacteria play an important role in bio-leaching. the results obtained from the indirect bio-leaching indicate the highest nickel recoveries of up to 83.65% and 80.18%, respectively, by the supernatants of acidithiobacillus ferrooxidans and delftia acidovorans, both measured at 90 °c for 3 h with a stirring speed of 370 rpm and s/l of 0.1, while the corresponding cobalt recovery rates have reached 86.93% and 83.94%, respectively. the iron dissolution rates in these conditions for the two studied bacteria are 64.34% and 54.41%, respectively. the nickel and cobalt extractions by the indirect bio-leaching of delftia acidovorans are, respectively, 29.84% and 23.75% higher than those for the direct bio-leaching, performed at 30 °c and 150 rpm of an incubator shaker for 30 days. for the indirect bio-leaching, the chemical control has a larger influence on the dissolution rate of the iron-rich laterite compared to the diffusion control. the activation energies of nickel and cobalt in the chemical control model are 40.07 and 39.08 kj/mol, respectively.