Arsenopyrite Dissolution and Bioscorodite Precipitation by Acidithiobacillus ferrivorans ACH under Mesophilic Condition

Abstract

Arsenopyrite is the most abundant arsenic-bearing sulfide mineral in the lithosphere, usually associated with sulfide gold ores. The recovery of this highly valuable metal is associated with the release of large quantities of soluble arsenic. One way to mitigate the effects of high concentrations of arsenic in solution is to immobilize it as scorodite precipitate, a more stable form. Hence, we addressed the scorodite formation capacity (under mesophilic conditions) of psychrotolerant Acidithiobacillus ferrivorans ACH isolated from the Chilean Altiplano. Bio-oxidation assays were performed with 1% arsenopyrite concentrate as unique energy source and produced solids were evaluated by X-ray diffraction (XRD) and QEMSCAN analysis. Interestingly, the results evidenced scorodite generation as the main sub-product after incubation for 15 days, due to the presence of the microorganism. Moreover, the QEMSCAN analysis support the XRD, detecting a 3.5% increase in scorodite generation by ACH strain and a 18.7% decrease in arsenopyrite matrix, implying an active oxidation. Finally, we presented the first record of arsenopyrite oxidation capacity and the stable scorodite production ability by a member of A. ferrivorans species under mesophilic conditions.

Effect of Micro-Nanobubbles on Arsenic Removal by Trichoderma atroviride for Bioscorodite Generation

“…These properties have been taken into consideration by our research group for the disposal of arsenic through scorodite formation, which offers several advantages over other biological processes that predominantly involve thermoacidophilic microorganisms. Unlike those processes, scorodite formation does not necessitate for long-time high temperatures or chemical oxidants for the precipitation process [ 65 ].…”

Editorial for Special Issue “Risk Assessment, Management and Control of Mining Contamination”

“…One of the strategies for solving this problem is using mineral bio-oxidation. Barahona et al [1] show that Acidithiobacillus ferrivorans can be used for immobilizing arsenic from minerals rich in this metal, as an alternative for conventional processes that currently use high temperatures. Leiva et al [2] treated solutions from zinc concentrate leaching to precipitate Fe, minimizing zinc loss, reducing the amount of waste precipitated during mining processes and obtaining solutions with iron content appropriate for electro-winning.…”