Abstract The interaction of gold cyanide complex with elemental sulphur and all metastable sulphur species has been studied using Density Functional Theory (DFT). The elemental sulphur and sulphide species formed during pre-treatment of refractory gold ores or dissolution of sulphide minerals form a series of metastable species including hydrosulphide, polysulphide, thionates, sulphite and finally sulphates which are known to have a detrimental effect on gold cyanidation. Previous researchers have attributed this effect mainly to passivation of the gold surface. However, interaction of dissolved aurocyanide with sulphur species has received almost no attention. Here, DFT molecular modelling has been used for the first time to describe the interaction of dissolved gold cyanide and sulphur species, and to explain the reduction and destabilisation potential of sulphur species in gold cyanidation. Computational modelling shows that sulphur species can have a significant negative effect on the stability of gold cyanide complex. Elemental sulphur and sulphide ion with −446.6 and − 198.4 kJ.mol−1 interaction energies have the most negative effect. S0 and S2− contribute to the destabilisation of gold cyanide via two different mechanisms of precipitation of AuCN and thiocyanate formation as well as reduction of gold by formation of sulphite and sulphates respectively. The effect of elemental sulphur can be neutralised by excess free cyanide in solution, while sulphide ion can still stay reactive toward gold cyanide in the presence of free cyanide. Addition of lead salt can decrease the inhibiting effect of sulphide ions by formation of lead sulphide. However, lead cannot eliminate the negative effect of elemental sulphur. It is concluded that oxidation of sulphur species can significantly overcome the adverse impact of sulphur species on the stability of gold cyanide complex. The destabilisation of gold cyanide complex by sulphur metastable species is introduced as one of the main mechanisms for loss of gold in sulphide gold ores.

中文翻译：

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硫物质对氰化金络合物的不稳定：计算视角

摘要 使用密度泛函理论 (DFT) 研究了氰化金络合物与元素硫和所有亚稳态硫物质的相互作用。在难处理的金矿石的预处理或硫化物矿物的溶解过程中形成的元素硫和硫化物物种形成一系列亚稳态物种，包括硫氢化物、多硫化物、亚硫酸盐、亚硫酸盐和最终的硫酸盐，这些已知对金氰化有不利影响。以前的研究人员将这种影响主要归因于金表面的钝化。然而，溶解的金氰化物与硫物质的相互作用几乎没有受到关注。在这里，首次使用 DFT 分子模型来描述溶解的氰化金和硫物质的相互作用，并解释金氰化中硫物质的还原和不稳定潜力。计算模型表明，硫物质会对氰化金配合物的稳定性产生显着的负面影响。具有−446.6 和−198.4 kJ.mol−1 相互作用能的元素硫和硫化物离子具有最大的负面影响。S0 和 S2- 分别通过 AuCN 沉淀和硫氰酸盐形成以及通过形成亚硫酸盐和硫酸盐还原金的两种不同机制导致氰化金不稳定。元素硫的影响可以被溶液中过量的游离氰化物中和，而在游离氰化物存在的情况下，硫化物离子仍然可以保持对氰化金的反应性。添加铅盐可降低硫化铅形成的硫化物离子的抑制作用。然而，铅不能消除元素硫的负面影响。结论是硫物种的氧化可以显着克服硫物种对氰化金配合物稳定性的不利影响。硫亚稳物质对氰化金络合物的破坏被认为是硫化金矿石中金流失的主要机制之一。