Causes of inhibition of bioleaching by Cu are also thermodynamic

Abstract

BACKGROUND Cu is an indispensable natural resource for society, as its use is widespread and essential for many technologies. Consequently, worldwide production is around 18×106 tn year−1, and close to 25% is produced by bioleaching. Bioleaching enables Cu extraction from minerals in atmospheric conditions by virtue of the catalytic activity of microorganisms. Microbial catalysis is mainly based on Fe3+ production as a leaching agent, a process known as Fe2+ bio‐oxidation. However, bio‐oxidation is inhibited by Cu2+ which limits the use of bioleaching with Cu mineral ores. RESULTS This paper, for the first time, examines the effect of Cu2+ on continuous Fe2+ bio‐oxidation using a packed bed bioreactor with supported cells. Bio‐oxidation was possible in the presence of 20 g L−1 Cu2+, with a less than 25% reduction in rate. About 15% of this drop in rate is due to biological inhibition and the rest to a reduction in oxygen solubility because of salting‐out. The biotic effect is reversed when Cu2+ is removed from the input, and the salting‐out effect can be overcome by improving aeration conditions. CONCLUSION These results, apart from having important ramifications for designing Cu ore bioleaching facilities, contribute to a more versatile and competitive idea of this clean technology. © 2018 Society of Chemical Industry

A new thiosalt depuration bioprocess for water- recycling in metallic sulphide mineral processing

“…Thiosalt bio-oxidation implies a noticeable fall in pH; in Figure 5, subsequent to the addition of S2O3 2-, an outlet pH level near to 1.5 was observed. Inside the bioreactor, the pH had to be similar since the flow in this kind of bioreactor fits the perfect mix model (Mazuelos et al, 2019). At this pH, S2O3 2disproportionation was promoted (r2) and, in consequence, SO3 2was generated.…”