Insight into the effect of potassium amyl xanthate on copper pollution caused by chalcopyrite bio-dissolution

Chalcopyrite has evolved into a crucial source of copper pollution, and xanthates inevitably coexisted with chalcopyrite in mine environments. However, the effect of xanthate on chalcopyrite bio-dissolution has not been illustrated yet. To fill this knowledge gap, the effect of potassium amyl xanthate (KAX) on copper release from chalcopyrite mediated by Acidithiobacillus ferrooxidans was investigated. The results revealed that KAX promoted chalcopyrite bio-dissolution, indicating more copper ions were released into the environment under these circumstances. KAX treatment groups displayed a lag period in ferrous ion oxidation, thereby providing a more favorable redox potential for chalcopyrite bio-dissolution. Bacterial adsorption experiments indicated the number of free cells increased with the addition of KAX, hence the Fe³⁺ regeneration was accelerated. Elemental composition analyses indicated the addition of KAX was conducive to reducing the formation of passivation substance (S_n^2-/S⁰). Additionally, the reduced surface tension of solution in KAX treatment groups was beneficial for the oxidant diffusing into the pores and cracks of chalcopyrite. This study provided a better comprehension of the effect of xanthate on copper pollution caused by chalcopyrite bio-dissolution, as well as a step toward better guidance in preventing copper pollution at source.