Production of gold from copper-rich gold ores has received particular attention due to some technical and economic challenges associated with the ready dissolution of most copper minerals during cyanide leaching. This leads to excessive consumption of cyanide by forming copper cyanide complexes, which adversely affect downstream recovery and cyanide detoxification processes. In this study, a novel method is proposed to precipitate copper from cyanide solutions using sodium dimethyldithiocarbamate (C₃H₆NNaS₂; SDDC). The influence of various parameters (i.e., reaction period (0–360 min.), concentration of SDDC (165–992 mM), [CN⁻]/[Cu] ratio (3–8), pH (10–12.5) and temperature (20–60 °C) on the precipitation of copper were investigated using synthetic copper-cyanide solutions. Increasing reaction time, concentration of SDDC and temperature were found to significantly improve the precipitation of copper. Increasing the ratio of [CN⁻]/[Cu] adversely affected the precipitation of copper with no precipitation being occurred at ratios of ≥6. Strong alkaline conditions appeared to have a slightly negative impact on the process. In the light of these findings, the response surface methodology (i.e., central composite design; CCD) was adopted to reveal the influence and interactions of [SDDC]/[Cu] ratio (21.0–126), initial concentration of copper (50–950 mg/L) and reaction period (15–360 min.) on the precipitation of copper. The analysis of the data confirmed that statistically significant parameters affecting the process were reaction time and [SDDC]/[Cu] ratio. It was also found that initial copper concentration did not significantly influence the process. Tests on real cyanide leach solutions derived from gold ores/concentrates demonstrated that the SDDC could selectively precipitate copper (as well as zinc and silver) from gold-bearing solutions. The activation energy (i.e., ≈67 kJ/mol) calculated by Arrhenius equation has indicated that the precipitation of copper is a chemically controlled reaction. Detailed characterisation of Cu-DDC precipitates was performed using SEM-EDS, FT-IR and particle size analysis. The precipitates (d₈₀ = 16 μm) are thin, rod-like particles in brownish colour. The recovery of copper from Cu-DDC precipitates using acid solutions (HCl, H₂SO₄ and HNO₃) was also investigated. Complete recovery of copper was achieved using HCl and HNO₃ solutions at high concentrations. The findings have suggested that SDDC is an effective reagent for selective precipitation of copper from cyanide leach solutions.

由于氰化物浸出过程中大多数铜矿物的现成溶解相关的一些技术和经济挑战，因此从富含铜的金矿石中生产黄金受到了特别的关注。这会通过形成氰化铜络合物而导致氰化物的过度消耗，从而不利地影响下游的回收率和氰化物的解毒过程。在这项研究中，提出了一种使用二甲基二硫代氨基甲酸钠（C ₃ H ₆ NNaS ₂； SDDC）从氰化物溶液中沉淀铜的新方法。各种参数（即，反应时间（的影响0-360分钟），SDDC（165-992毫米），[CN的浓度。^-使用合成氰化铜溶液研究了铜沉淀中的] / [Cu]比（3–8），pH（10–12.5）和温度（20–60°C）。发现增加反应时间，SDDC浓度和温度可显着改善铜的沉淀。增加的[CN比率^-] / [Cu]不利地影响了铜的析出，当≥6时没有析出。强碱性条件似乎对该工艺有轻微的负面影响。根据这些发现，采用响应面方法（即中央复合设计； CCD）揭示了[SDDC] / [Cu]比（21.0–126），铜的初始浓度（50–50％）的影响和相互作用。 950 mg / L）和反应时间（15-360分钟）。数据分析证实，影响该过程的统计学上重要的参数是反应时间和[SDDC] / [Cu]比。还发现初始铜浓度不会显着影响该过程。对源自金矿石/精矿的真实氰化物浸出溶液的测试表明，SDDC可以从含金溶液中选择性地沉淀出铜（以及锌和银）。通过Arrhenius方程计算得出的活化能（即≈67 kJ / mol）表明，铜的沉淀是化学控制的反应。使用SEM-EDS，FT-IR和粒度分析对Cu-DDC沉淀物进行了详细的表征。沉淀物（d₈₀  = 16μm）是呈褐色的棒状细颗粒。还研究了使用酸性溶液（HCl，H ₂ SO ₄和HNO ₃）从Cu-DDC沉淀物中回收铜。使用高浓度的HCl和HNO ₃溶液可完全回收铜。研究结果表明，SDDC是从氰化物浸出溶液中选择性沉淀铜的有效试剂。