Cyanidation circuits that treat sulfidic ores may contain one or more of the following reduced sulfur species: sulfide (HS⁻), polysulfides (S_n²⁻), thiocyanate (SCN⁻), thiosulfate (S₂O₃²⁻), trithionate (S₃O₆²⁻), tetrathionate (S₄O₆²⁻), pentathionate (S₅O₆²⁻), hexathionate (S₆O₆²⁻). The actual speciation of the reduced sulfur species in the circuits will primarily depend on the redox potential, pH, cyanide levels and existing sulfur species in recycled process water, as well as the presence of other reactive metal species. Higher polythionates (i.e. tetra-, penta- and hexathionate) present in leach solutions react with cyanide ions rapidly and consume the available cyanide causing lower metal recoveries at cyanide leaching plants. When higher polythionate ions are degraded to trithionate, cyanide consumption by these ions could be lowered, and metal recoveries would increase.

This study presents the sulfur species formed and a practical polythionate degradation method that can be applied within the cyanidation circuits. The possibility of increased gold and silver recoveries and decreased cyanide consumptions by controlling the higher polythionates (S_nO₆²⁻, n = 3,4,5,6) with the addition of sulfite salts to the cyanide leach slurries was studied. Experimental results showed that average gold and silver recoveries increased by 13.3% and 28.8%, respectively at 500 ppm (mg/L) NaCN and 300 ppm (mg/L) sulfite (SO₃²⁻) concentration levels compared to the control experiments where no sulfite was added to the leach slurries. Additionally, higher sulfite concentrations in the leach slurries resulted in lower tetrathionate and higher thiosulfate, trithionate and available cyanide concentrations.

处理硫化矿石的氰化回路可能包含一种或多种以下还原硫物质：硫化物 (HS ^- )、多硫化物 (S _n ^2- )、硫氰酸盐 (SCN ^- )、硫代硫酸盐 (S ₂ O ₃ ^2- )、连_三硫酸盐 ( S ₃ O ₆ ²⁻ )、连四硫酸盐 (S ₄ O ₆ ²⁻ )、连五硫酸盐 (S ₅ O ₆ ²⁻ )、六硫酸盐 (S ₆ O ₆ ^{2− )}）。回路中还原硫物质的实际形态主要取决于氧化还原电位、pH 值、氰化物水平和循环工艺水中现有的硫物质，以及其他活性金属物质的存在。浸出溶液中存在的高级连多硫酸盐（即四、五和六硫酸盐）会与氰化物离子迅速反应并消耗可用的氰化物，从而导致氰化物浸出厂的金属回收率降低。当较高的连多硫酸根离子降解为连三硫酸根时，这些离子对氰化物的消耗会降低，金属回收率会增加。

本研究介绍了形成的硫物质和可在氰化回路中应用的实用连多硫酸盐降解方法。研究了通过 向氰化物浸出浆中添加亚硫酸盐来控制较高的连二硫酸盐(S _n O ₆ ^2- , n = 3,4,5,6)来提高金和银回收率并降低氰化物消耗的可能性。实验结果表明，在 500 ppm (mg/L) NaCN 和 300 ppm (mg/L) 亚硫酸盐 (SO ₃ ²⁻ ) 条件下，金和银的平均回收率分别提高了 13.3% 和 28.8%) 浓度水平与未向浸出浆液中添加亚硫酸盐的对照实验相比。此外，浸出浆液中较高的亚硫酸盐浓度导致较低的连四硫酸盐和较高的硫代硫酸盐、三硫酸盐和可用氰化物浓度。