Cyanidation, as the primary method for gold extraction, poses significant risks to the environment and animals. Therefore, an eco-friendly, sustainable, and effective leaching approach has been devised for extracting gold from a gold concentrate after calcination, utilizing copper(II)-ammonia and thiourea. This research focuses primarily on optimizing leaching conditions, gold recovery from leach solution, and cyclic utilization of the leaching solution. Furthermore, we investigated the potential mechanisms behind the leaching and recovery processes using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and thermodynamic analysis. The leaching process exhibits a spontaneous reaction, and the mechanism for alkaline thiourea leaching of gold is as follows: (a) reduction of Cu(NH) to Cu(TU), (b) oxidation of Au(0) to Au(TU) and (c) oxidation of Cu(TU) back to Cu(NH), in the presence of oxygen, regenerating the catalyst. Under optimal leaching conditions, the proposed method achieves a gold extraction efficiency of approximately 86.6%, approaching that of cyanidation. The barren leach solution can be reused for subsequent leaching experiments, with consistent gold extraction efficiency and thiourea consumption. Therefore, this method presents a promising alternative to gold leaching via cyanidation.

中文翻译：

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通过铜-氨-硫脲系统和活性炭从煅烧精矿中回收金的简便而新颖的方法

氰化作为提金的主要方法，对环境和动物构成重大风险。因此，我们设计了一种环保、可持续且有效的浸出方法，利用铜(II)-氨和硫脲从煅烧后的金精矿中提取金。本研究主要集中于优化浸出条件、从浸出液中回收金以及浸出液的循环利用。此外，我们使用扫描电子显微镜结合能量色散 X 射线光谱、X 射线光电子能谱和热力学分析研究了浸出和回收过程背后的潜在机制。浸出过程呈现自发反应，碱性硫脲浸出金的机理如下：(a) Cu(NH)还原为Cu(TU)，(b) Au(0)氧化为Au(TU) (c) 在氧气存在下，将 Cu(TU) 氧化回 Cu(NH)，从而使催化剂再生。在最佳浸出条件下，该方法的金提取效率约为86.6%，接近氰化法。贫浸液可重复用于后续浸出实验，提金效率和硫脲消耗量一致。因此，该方法为氰化浸金提供了一种有前途的替代方法。