Pyrite and arsenopyrite are known to be the most common gold-bearing sulfide minerals in refractory gold ores. Traditionally, these minerals have been first oxidized by roasting, acidic pressure oxidation or bio-oxidation to release gold, after which the gold is dissolved in the subsequent cyanide leaching step. The chloride (chloride-bromide) solution presents an alternative cyanide-free media, which is able not only to leach gold-bearing sulfide minerals, but also gold, in a single unit process. Therefore, the current study presents an investigation of simultaneous sulfide oxidation and gold leaching from refractory (sulfidic) and double refractory (sulfidic and preg-robbing) gold concentrates. The results show that gold extraction from the investigated refractory concentrate was linearly dependent on the sulfide oxidation: 97% sulfide oxidation resulting in 99% gold extraction, 67% sulfide oxidation resulting in 81% gold extraction, and 46% sulfide oxidation resulting in 67% gold extraction. However, with double refractory concentrate, gold extraction was as low as 18% despite 97% sulfide oxidation ([Cl^-]_aq,0 = 6.3 mol/L, [Br^-]_aq,0 = 1.0 mol/L, and [Cu²⁺]_aq,0 = 1.6 mol/L). In order to mitigate the challenges related to gold losses due to preg-robbing, active carbon in chloride leach (CICl) as well as the addition of lead nitrate were investigated. With CICl, the gold recovery could be increased significantly (67%). Further, addition of lead nitrate to CICl was shown to improve gold recovery substantially (88%). The investigation shows that the presented cyanide-free leaching approach can address the refractory nature of gold concentrates in atmospheric pressure - the simultaneous oxidation of sulfide minerals and gold in a single unit process providing new horizons for the future of the utilization of refractory gold ores.

众所周知，黄铁矿和毒砂是难熔金矿石中最常见的含金硫化物矿物。传统上，这些矿物首先通过焙烧、酸性压力氧化或生物氧化进行氧化以释放金，然后金在随后的氰化物浸出步骤中溶解。氯化物（氯化物 - 溴化物）溶液提供了一种替代的无氰化物介质，它不仅能够在单个单元过程中浸出含金硫化物矿物，还能够浸出金。因此，目前的研究提出了同时从难熔（硫化）和双难熔（硫化和预浸）金精矿中同时进行硫化物氧化和金浸出的研究。结果表明，从研究的耐火精矿中提取金与硫化物氧化呈线性关系：97% 的硫化物氧化导致 99% 的金提取，67% 的硫化物氧化导致 81% 的金提取，46% 的硫化物氧化导致 67% 的金提取。然而，使用双耐火精矿时，尽管硫化物氧化 97%（[Cl^- ] _aq,0  = 6.3 mol/L, [Br ^- ] _aq,0  = 1.0 mol/L, 和 [Cu ²⁺ ] _aq,0 = 1.6 摩尔/升）。为了减轻与因预浸料抢夺而导致的金损失相关的挑战，研究了氯化物浸出 (CICl) 中的活性炭以及添加硝酸铅。使用 CICl，金回收率可以显着提高 (67%)。此外，向 CICl 中添加硝酸铅显示出显着提高金回收率 (88%)。调查表明，所提出的无氰浸出方法可以解决金精矿在常压下的难熔性质——硫化物矿物和金在单个单元过程中同时氧化，为难熔金矿的未来利用提供了新的视野。