Enhanced copper extraction in the chalcopyrite bioleaching system assisted by microbial fuel cells and catalyzed by silver-bearing ores

Abstract

Chalcopyrite is the most abundant copper ores in nature and the main source of copper resources. Low energy consumption but slow kinetics occurred in the microbial fuel cell (MFC)-assisted chalcopyrite bioleaching process. High price and low recovery limited the use of silver-bearing chemicals as catalysts for the chalcopyrite bioleaching. Besides, the process of extracting silver-bearing chemicals from silver-bearing ores was complex and energy-intensive. Silver-bearing ores were low-cost and could release Ag+, which could be used as the alternative to silver-bearing chemicals in the chalcopyrite bioleaching. This study proposed the catalytic effect and catalytic pathway of silver-bearing ores on copper extraction in the MFC-assisted chalcopyrite bioleaching. After 216 days bioleaching, the maximum Cu2+ leaching efficiency of 10.03% was achieved in column reactor mixed with silver-bearing ores. Replacing silver-bearing chemicals (Ag2SO4) with silver-bearing ores in MFC-assisted bioleaching processes promoted the copper extraction efficiency by 1.5 times (10.03 % vs. 6.63 %). In contrast, the Cu2+ leaching efficiency was observed to be 5.37 % in the absence of silver. Compared with the regeneration of Ag+ only from Ag2S in the system mixed with Ag2SO4, the continuous release of Ag+ from silver-bearing ores maintained an appropriate concentration, which facilitated the bacterial growth and chalcopyrite dissolution. Ag+ promoted the formation of porous surfaces and increased surface roughness, which enhanced the adsorption of bacteria on chalcopyrite surface. Additionally, both Ag+ and MFC better reduced passivation and maintained the optimum ORP, which facilitated the continuous dissolution of chalcopyrite.