Thiosulfate leaching is increasingly recognized as an environmentally sustainable alternative tocyanidation for extracting gold. One of the primary challenges in this field is identifying an effective stabilizer for the Cu(II) oxidant that simultaneously ensures efficient gold leaching and low thiosulfate consumption. This work introduces pentetic acid (DTPA) as a stabilizer for Cu(II) oxidant, forming a novel oxidation system based on the stable-chelated CuDTPA3− complex. Comparative leaching using (NH4)2S2O3 and Na2S2O3 highlight the beneficial role of ammonia (NH3) in enhancing the oxidation capability of the stable CuDTPA3− complex. The proposed mechanism suggests that NH3 contributes to the formation of a mixed [Cu(DTPA)(NH3)]3− complex with enhanced chemical reactivity. Additionally, DTPA is shown to effectively maintain the stability of the leaching system, thereby improving gold leaching, reducing thiosulfate consumption, and mitigating passivation. Through precise parameters control, a satisfactory gold leaching from a pretreated gold concentrate achieved a high efficiency of 97.8 %, with a low (NH4)2S2O3 consumption (8.7 kg/t-ore). Furthermore, the actual operation process can be facile designed by using more cost-effective leaching chemicals such as Na2S2O3 with a little addition of NH4OH or various ammonium salts, like (NH4)2SO4, CH3COONH4, and NH4Cl. This study provides valuable insights for advancing the commercial viability of environmentally friendly gold leaching processes.

中文翻译：

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戊酸/氨协同稳定 Cu（II） 作为金绿色硫代硫酸盐浸出的高效氧化剂


硫代硫酸盐浸出越来越被认为是一种环境可持续的金提取绿氰化法。该领域的主要挑战之一是确定一种有效的 Cu（II） 氧化剂稳定剂，同时确保高效的金浸出和低硫代硫酸盐消耗。本研究介绍了戊酸 （DTPA） 作为 Cu（II） 氧化剂的稳定剂，基于稳定螯合的 CuDTPA3− 复合物形成了一种新型的氧化体系。使用 （NH4）2S2O3 和 Na2S2O3 的比较浸出突出了氨 （NH3） 在增强稳定的 CuDTPA3− 复合物的氧化能力方面的有益作用。所提出的机制表明，NH3 有助于形成具有增强化学反应性的混合 [Cu（DTPA）（NH3）]3− 络合物。此外，DTPA 被证明可以有效保持浸出系统的稳定性，从而改善金浸出，减少硫代硫酸盐消耗，并减轻钝化。通过精确的参数控制，从预处理的金精矿中得到令人满意的金浸出，实现了 97.8% 的高效率，并且 （NH4）2S2O3 消耗量很低（8.7 kg/t-ore）。此外，通过使用更具成本效益的浸出化学品（如 Na2S2O3），并添加少量 NH4OH 或各种铵盐（如 （NH4）2SO4、CH3COONH4 和 NH4Cl），可以简化实际操作过程的设计。这项研究为提高环保型金浸出工艺的商业可行性提供了宝贵的见解。