1、 The core role of traditional mainstream pharmaceuticals (represented by sodium cyanide)

Sodium cyanide is currently the most widely used gold extraction agent worldwide, and its mechanism of action is very classic:

1. Dissolving effect (core chemical reaction)：

• Under alkaline and aerobic conditions, cyanide ions undergo complexation reactions with fine gold particles.

• chemical equation：4Au + 8NaCN + O₂ + 2H₂O → 4Na[Au(CN)₂] + 4NaOH

• Essence of FunctionOxidation of elemental gold (Au ⁰) and formation of highly stable, water-soluble compounds with cyanide (CN ⁻) ionsDicyanide complex ion [Au (CN) ₂⁻]This is a crucial step in transferring gold from solid ore to aqueous solution.

• Cyanide exhibits high selectivity towards gold and silver. Although it can also react with metals such as copper, zinc, and iron, under controlled concentration and conditions, it can preferentially or effectively dissolve gold and silver, thereby achieving a certain degree of separation.

However, while cyanide plays a role in "efficient dissolution", it also brings a fatal side effect: its high toxicity poses a huge risk to the environment and social security.

2、 The role of modern environmentally friendly gold enhancing agents (upgrade and expansion)

The core function of environmental protection agents is to accomplish the above-mentioned tasks“Efficient dissolution of gold”On the basis of this core task,Added or strengthened the following key roles：

1. Safe substitution function：

• thioureaFormation of cationic complexes under acidic conditions[Au(CS(NH₂)₂)₂]⁺。

• thiosulfateFormation of anionic complexes under ammoniacal conditions[Au(S₂O₃)₂]³⁻。

• halogen system(such as chlorination): forms chloroauric acid ions[AuCl₄]⁻。

• Core tasks remain unchangedReplace cyanide by dissolving gold through different chemical mechanisms such as complexation, oxidation, etc. For example:

• added valueThe medication itselfLow toxicity or non-toxicThe reaction products are also environmentally friendly, fundamentally eliminating the management risks and environmental pollution of highly toxic substances.

• The role of "robbing gold" carbonaceous mineralsSome medications canPassivation or shieldingThe activated carbon in the ore prevents it from adsorbing dissolved gold, thereby ensuring the recovery rate.

• The role of "package" type gold depositsSome medications haveMild oxidizing propertiesIt can slowly etch sulfides (such as pyrite) that encapsulate gold, opening channels to expose the gold, while cyanide is almost ineffective against this.

• The effect on high impurity minerals: HavingHigher chemical selectivityFor example, thiosulfate is much less sensitive to copper than cyanide, and can significantly reduce reagent consumption and avoid excessive interference from impurities when dealing with high copper gold mines.

• can serve asImmersion aidorcatalystCombined with low-dose cyanide,Accelerate gold immersion speed and improve recovery rateThusReduce the total amount of cyanide usedTo achieve reduced toxicity and increased efficiency.

• Adapt to a wider range of ore properties and provide customized solutions for mines with different characteristics.

Summary: Evolution of the Action of Gold Extracting Agents

In summary, the role of gold mining reagents has evolved from a single "solubilizer" to a comprehensive solution that integrates "efficient solubilizers," "environmental safety officers," and "technical experts. 其发展的主线，就是在保障甚至提升经济效益的前提下，持续降低环境足迹，推动矿业可持续发展。