The oxidative decomposition of thiosulfate is one the main problems found in the thiosulfate leaching of precious metals. This work presents a detailed analysis of the effect of different dissolved components on the silver sulfide dissolution kinetics and efficiency faced by the thiosulfate-citrate‑copper-ammonia system. The analysis comprises the quantification of thiosulfate concentration; furthermore, it is discussed the effect of copper sulfides and copper hydroxides -formed in the leaching system- on the thiosulfate decomposition and silver dissolution efficiency. The results revealed that citrate promotes the complexation of cupric ions decreasing the thiosulfate consumption in the leaching system. The individual and combined effects of copper solid species (Cu(OH)₂, CuS, Cu₂S and solid residues obtained from silver sulfide leaching) on the thiosulfate stability and silver extraction efficiency, showed that the thiosulfate decomposition that occurs in the system is not significantly related to these copper species, while the silver extraction (~80%) does not show any substantial change. However, the presence of Cu₂S and a small amount of dissolved silver have certain effect on the the partial in-situ regeneration of thiosulfate in the leaching system. Finally, it was also found that the silver sulfide dissolution is passivated obtaining an 80% of silver extraction. Such passivation is mainly attributed to: a) the precipitation of copper-sulfide and copper-hydroxide species on the unreacted silver sulfide sites; these copper phases act as a physical barrier which inhibits the direct contact of fluid reactants with the silver sulfide, and b) the silver sulfide dissolution reaches an equilibrium state.

硫代硫酸盐的氧化分解是在硫代硫酸盐浸出贵金属中发现的主要问题之一。这项工作详细分析了不同溶解组分对硫代硫酸盐-柠檬酸盐-铜-氨系统所面临的硫化银溶解动力学和效率的影响。分析包括对硫代硫酸盐浓度的定量；此外，还讨论了在浸出系统中形成的硫化铜和氢氧化铜对硫代硫酸盐分解和银溶解效率的影响。结果表明，柠檬酸盐促进铜离子的络合，减少了浸出系统中硫代硫酸盐的消耗。铜固体物质（Cu（OH）₂，CuS，Cu ₂S和从硫酸银浸出获得的固体残留物）对硫代硫酸盐的稳定性和银提取效率的影响表明，系统中发生的硫代硫酸盐分解与这些铜种类没有显着关系，而银的提取（〜80％）却不显示任何重大变化。但是，Cu ₂的存在S和少量溶解的银对浸出系统中硫代硫酸盐的部分原位再生有一定影响。最后，还发现钝化了硫化银溶解，获得了80％的银提取量。这种钝化主要归因于：a）硫化铜和氢氧化铜物质在未反应的硫化银位点上的沉淀；这些铜相充当物理屏障，抑制了流体反应物与硫化银的直接接触，并且b）硫化银的溶解达到了平衡状态。