Biological and chemical control in copper bioleaching processes: When inoculation would be of any benefit?

Enhancement in copper extraction from chalcopyrite by re-inoculation of different acidophilic, moderately thermophilic microorganisms

“…1), especially between days 5 and 15. In accordance with the analysis of a conceptual mathematical model, Vargas et al (2014) also indicated that the bioleaching process in the initial stage of bioleaching is only biologically controlled, and improvement of copper leaching rate could be obtained in this case through an increase of bacterial population by inoculation.…”

“…At this condition, the co-precipitation of dissolved copper ions with jarosite was found (Fig. 4a) (Acevedo, 2000;Zeng et al, 2010), which decreased the reactivity of the sulfide mineral and caused the further microbial suppression of copper extraction (Hackl et al, 1995;Vargas et al, 2014). Similarly, other reports (Hiroyoshi et al, 1999;Third et al, 2000) also noted that a significant increase in cell numbers of ironoxidising microorganisms inhibited the leaching process of chalcopyrite when the bioleaching conditions in the solution were not favourable.…”

“…2b). In conclusion, how to maximize the improvement in iron oxidation and leaching during the early bioleaching stage by re-inoculation of acidophilic microorganism is of great importance in determining the dissolution kinetics and level of chalcopyrite (Das et al, 1999;Vargas et al, 2014).…”

“…Similarly, other reports (Hiroyoshi et al, 1999;Third et al, 2000) also noted that a significant increase in cell numbers of ironoxidising microorganisms inhibited the leaching process of chalcopyrite when the bioleaching conditions in the solution were not favourable. Therefore, an instantaneous and excessive increase in ferrous-oxidising bacterial population or activity at the advanced or later stage of chalcopyrite bioleaching couldn't facilitate copper sulfide dissolution (Vargas et al, 2014).…”