One of the major challenges in processing gold-bearing ores is the presence of gold encapsulated in refractory sulfide minerals, particularly pyrite. These ores, due to their high resistance to cyanide leaching, are known as refractory gold ores. In conventional cyanidation processes, gold recovery from these ores is typically low. Therefore, the use of oxidative pre-treatment methods has been considered an effective approach for breaking down the sulfide structure an‎d liberating the gold. In this study, the effect of oxidation using ozone on enhancing gold dissolution from gold-containing ores was investigated. To assess the performance of ozonation, experiments were conducted on both refractory sulfide feed an‎d the residue (cake) from regular cyanidation. In these experiments, ozone gas was injected into the pulp as bubbles under various durations an‎d pH conditions. The results showed a recovery of 92.5% after 4 hours of ozonation on the feed, an‎d 93.84% recovery after 8 hours of ozonation on the cyanidation residue, indicating the liberation of 38.39% of refractory gold. In contrast, gold recovery from the untreated feed (without pre-oxidation) was 89.06%. In the next phase, the use of air an‎d ozone nanobubbles was eva‎luated. These tests were conducted at different time intervals to study the effect of nanobubbles on the oxidation of sulfide minerals an‎d gold liberation. The findings showed that injecting air nanobubbles for 30 minutes led to a recovery of 88.4%, while injecting ozone nanobubbles for 5 minutes under similar conditions resulted in a 92.64% recovery. Finally, a flotation concentrate was prepared an‎d subjected to similar nanobubble injection tests. The results demonstrated that injecting ozone nanobubbles is an effective method for the pre-treatment of refractory minerals, significantly enhancing gold dissolution. The highest recovery was achieved when ozone was injected as nanobubbles into the concentrate for 15 minutes, achieving a recovery of 90.54%. These results confirm the high potential of using ozone nanobubbles to improve the cyanidation process for refractory sulfide ores.

مهدي نصيري سروي , ابراهيم عظيمي

محمدرئوف حسيني

علي احمدي عامله , بيژن طاهري