Enhanced oxidation mechanism of arsenopyrite in two-stage oxidation process applying bio-oxidation waste solution

• Applying bio-oxidation waste solution in a two-stage oxidation process significantly enhances arsenopyrite bio-oxidation efficiency. • Chemical oxidation with BOS disrupts the mineral surface structure, reduces particle size, and forms nitrogenous substances, promoting Fe3+ cycling and mitigating sulfur film inhibition. • After 18 days, the two-stage process achieves As, Fe, and S extraction rates of 88.8%, 86.7%, and 74.7%, representing increases of 50.8%, 47.1%, and 46.0% over one-stage bio-oxidation. • The study provides a sustainable, environmentally friendly pretreatment strategy for arsenic-containing refractory gold ores, improving gold recovery without additional metal ion supplementation.