Abstract The development of cyanide-free gold leaching methods is becoming increasingly important due to the treatment of complex ores, where treatment by cyanidation is not economically viable. Cupric chloride leaching provides an alternative leaching process to replace cyanidation. A detailed simulation of refractory gold concentrate processing by cupric chloride leaching is presented in this study. The simulation with mass and energy balances was built to be used as life cycle inventory data to evaluate the environmental impacts of the development stage cupric chloride process. Three cases, the Base Case (125 g/L Cl-), Mild Case (50 g/L Cl-), and Extremely Mild Case (20 g/L Cl-), were investigated in two flowsheet options. Loss of gold to wash waters was observed in the Flowsheet 1 cases, and therefore Flowsheet 2, with the recirculation of wash water to solvent extraction, was developed and investigated in order to achieve higher gold recovery. The gold extraction improved from around 85% to 99%. Chemical consumption (NaCl, NaBr, CuCl2) was greatly affected by the leaching conditions, higher concentrations consuming more initial chemicals. In milder conditions, efficient recycling of chlorides could be obtained in the process, and no addition of NaCl was required. In the Extremely Mild Case, the chloride concentration was close to sea water conditions (20 g/L), where sea water could be used to provide chlorides for the process, and the effluent waters could be disposed of in the sea after purification. The global warming potential was estimated to be 12.5 t CO2-e/kg Au in chloride leaching and was further decreased to 10.6 t CO2-e/kg Au in the mildest conditions (20 g/L Cl-). The milder chloride leaching conditions (20 g/L Cl- and 50 g/L Cl-) were shown to decrease the acidification potential, eutrophication potential, and water depletion.

中文翻译：

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基于工艺模拟的无氰难熔金精矿加工生命周期评估——案例研究：氯化铜浸出

摘要 由于处理复杂的矿石，氰化处理在经济上不可行，无氰浸金方法的发展变得越来越重要。氯化铜浸出提供了替代氰化的替代浸出工艺。本研究详细模拟了氯化铜浸出法处理难熔金精矿。建立质量和能量平衡的模拟，用作生命周期清单数据，以评估开发阶段氯化铜工艺对环境的影响。在两个流程选项中研究了三种情况，基本情况 (125 g/L Cl-)、轻度情况 (50 g/L Cl-) 和极轻度情况 (20 g/L Cl-)。在流程图 1 的情况下观察到金在洗涤水中的损失，因此流程图 2，将洗涤水再循环到溶剂萃取中，开发和研究以实现更高的金回收率。金提取率从大约 85% 提高到 99%。化学品消耗（NaCl、NaBr、CuCl2）受浸出条件的影响很大，较高的浓度消耗更多的初始化学品。在较温和的条件下，该过程可以获得氯化物的有效回收，并且不需要添加 NaCl。在极温和的情况下，氯化物浓度接近海水条件（20 g/L），可以利用海水为工艺提供氯化物，净化后的废水可以在海中处理。在氯化物浸出中，全球变暖潜势估计为 12.5 t CO2-e/kg Au，并进一步降至 10。在最温和的条件下 (20 g/L Cl-) 为 6 t CO2-e/kg Au。较温和的氯化物浸出条件（20 g/L Cl- 和 50 g/L Cl-）显示出可降低酸化潜力、富营养化潜力和水分消耗。