There is a vast amount of globally underutilized low-grade mine tailings and leach residues, including those from primary processing of gold. In this research, the target is to recover the remaining gold (10.9 g/t) from weathered refractory iron-rich residue that had previously been subject to autoclave oxidation, subsequent cyanidation in a conventional carbon-in-leach (CIL) circuit as well as storage at tailings area. Chloride leaching has been considered as one of the most promising cyanide-free gold leaching methods and it has shown positive outcomes in treating primary gold ores, concentrates, and flotation tailings. Therefore, in the current study, the iron-rich residue investigated was subjected to chloride leaching combined with simultaneous carbon adsorption. The investigated parameters included leaching time (2–8 h), chloride concentration ( = 0.2–5 M), type and concentration of oxidant ( = 0.1–1 M), as well as type and concentration of activated carbon (14–25 g/L), whereas S/L ratio (100 g/L), acidity ( = 1), and temperature (90 °C) were kept constant. Leaching results indicate that up to 40% of the remaining gold could still be recovered from the investigated residue with optimized chloride leaching. According to the results, the most important parameter for gold recovery was the leaching time. Moreover, of the studied oxidants, cupric ions were shown to contribute more to gold recovery when compared to ferric ions (35% vs. 24% at = 0.1 M). Nevertheless, an increase of cupric concentration from 0.1 M (low-concentrated) to 0.5 M, resulted in only a slight increase in gold recovery (from 36% to 40%), whereas no further improvement in gold recovery was achieved with a 1 M cupric concentration. Two studied activated carbon products showed equal effectiveness in gold adsorption. In-situ carbon adsorption was shown to occur effectively in chloride media, as all dissolved gold could be detected in the activated carbon, and the concentration of remaining gold in the pregnant leach solution was minimal (< 0.02 mg/L). These findings indicate that low-concentrated chloride leaching of leach residues from industrial gold processes can allow an enhanced recovery of gold from previously mined and treated raw materials.

中文翻译：

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通过氯化物浸出和碳吸附从氰化残渣中回收金 – CICL 工艺的初步结果


全球有大量未充分利用的低品位尾矿和浸出残渣，其中包括来自黄金初级加工的残渣。在这项研究中，目标是从风化的难熔富铁残渣中回收剩余的金（10.9 克/吨），这些残渣之前经过高压釜氧化，随后在传统碳浸出 (CIL) 回路中进行氰化作为尾矿区的储存。氯化浸出被认为是最有前途的无氰浸金方法之一，在处理原生金矿石、精矿和浮选尾矿方面已显示出积极的效果。因此，在当前的研究中，对富铁残渣进行了氯化物浸出并同时进行碳吸附。研究的参数包括浸出时间（2-8 h）、氯化物浓度（= 0.2-5 M）、氧化剂的类型和浓度（= 0.1-1 M）以及活性炭的类型和浓度（14-25 g） /L），而 S/L 比（100 g/L）、酸度（= 1）和温度（90 °C）保持恒定。浸出结果表明，通过优化氯化物浸出，仍可从研究的残留物中回收高达 40% 的剩余金。根据结果​​，金回收最重要的参数是浸出时间。此外，在所研究的氧化剂中，与三价铁离子相比，铜离子对金回收的贡献更大（= 0.1 M 时为 35% vs. 24%）。然而，铜浓度从 0.1 M（低浓度）增加到 0.5 M，仅导致金回收率略有增加（从 36% 增加到 40%），而 1 M 铜浓度并未实现金回收率的进一步提高。铜浓度。 两种研究的活性炭产品在金吸附方面表现出相同的效果。原位碳吸附在氯化物介质中有效发生，因为所有溶解的金都可以在活性炭中检测到，并且母浸出液中剩余金的浓度极小（< 0.02 mg/L）。这些发现表明，对工业黄金加工过程中的浸出残渣进行低浓度氯化物浸出可以提高从先前开采和处理的原材料中回收黄金的能力。