Oxidation of Gold-Bearing Pyrite by Ammonium Persulfate

Abstract

Advanced oxidation processes (AOPs) are widely used in water treatment. Thus, we applied an FeSO 4 -S 2 O 8 2− system to the oxidation pretreatment of Carlin-type primary gold ore. Based on this research, we have continued to explore the initiator (nZVI/FeO/FeSO 4 ) in the ammonium persulfate (APS) system. In this study, when the concentration of nano-zero-valent iron (nZVI) was 0.0895 mol/L, the APS concentration was 0.088 mol/L, and the leaching time was 1 h, the oxidation of pyrite reached 92.69%. A quantitative analysis method was established for intermediate SO 4 − •, and it was determined that the concentration of SO 4 − • during the oxidation of pyrite in the nZVI-APS system rapidly increased to 7.533 mmol/L within 7 min, was maintained above 6.5 mmol/L for 7 to 15 min, and then rapidly decreased to 0 mmol/L. Within a certain period of time, the stable concentration of SO 4 − • ensured a rapid increase in the pyrite oxidation rate. The analysis of the oxidized leaching residue shows that the surface of the pyrite in the nZVI(FeO)-APS system had a large specific surface area and a fine particle structure of iron hydroxide oxide (FeOOH), the leaching residue formed depressions and cracks, and the surface area of the pyrite increased, which was conducive to the subsequent contact between leachant and gold. In conclusion, the nZVI(FeO)-APS system can effectively and rapidly oxidize pyrite at room temperature and form a good pulp environment, thereby creating favorable conditions for the subsequent improvement of the gold leaching rate.

Counterion effects on the alkali dissolution mechanism of quartz

“…In the present work, for the first time, to our best knowledge, the influence of counterions produced by the pre-treatment of golden iron ore on quartz dissolution during the pre-treatment process of Carlin-type gold ore is being reported. Our team has been studying Carlin type gold ores (Ma et al, 2020;Tang et al, 2021), the main gold carrying minerals of this ore are pyrite and quartz. Both pyrite and the reagent initiator nano iron powder in the leaching process will produce Fe 2+ .…”