Cyanide Leaching for Gold Extraction: Pros and Cons Explained

01Characteristics of gold extraction by cyanide leaching

The reason why gold can react with cyanide is that gold usually exists in the form of a single substance in nature and has relatively stable chemical properties. However, in the cyanide solution, in the presence of oxygen, gold will be oxidized and combined with cyanide ions to form a stable complex. This complex has good solubility in water, allowing gold to be extracted from the ore.

The cyanide leaching method is mostly suitable for processing sulfide gold minerals with fine gold particles and high floatability, such as gold-bearing quartz vein ores, gold-bearing sulfide ores containing multiple valuable metals, and gold-bearing ores containing graphite. In addition, for minerals with more complex ore properties, enrichment can be achieved by flotation + cyanide leaching.

02Advantages of Cyanide Leaching for Gold Extraction

High leaching rate and good selectivity: Cyanide leaching can effectively extract gold from ore, and the gold recovery rate can usually reach more than 90%, because the reaction between gold and cyanide has high selectivity and reaction efficiency, and can fully dissolve the gold in the ore.

Mature and stable process: After years of development and improvement, a set of mature process flows has been formed. The process mainly includes ore crushing, grinding, cyanide leaching, solid-liquid separation, gold extraction and refining. Each link has corresponding equipment and technical support, the operation is relatively simple, and it is easy to achieve industrial production.

Low gold selection cost: In terms of reagents, although cyanide has certain toxicity, its price is relatively low. In the cyanide leaching process, the amount of cyanide used is usually small, generally about 0.05%-0.5% of the mass of the ore. The requirements for equipment are also low, so the equipment investment and maintenance costs are also relatively low. In terms of energy consumption, the process is carried out at normal temperature and pressure, does not require a large amount of energy, and energy consumption can be reduced by about 30%-50%.

03Disadvantages of Cyanide Leaching for Gold Extraction

Cyanide is toxic: Cyanide is a highly toxic substance that has serious harm to the human nervous system, respiratory system, and cardiovascular system. In the process of cyanide leaching for gold extraction, if the operation is improper, cyanide may leak into the environment and pollute the surrounding soil, water bodies, and ecological environment. For example, cyanide leaking into the water body will cause the death of organisms in the water and destroy the ecological balance. In addition, cyanide may also be transmitted through the food chain, posing a potential threat to human health.

Limited scope of application: Although this method has a certain effect on most common types of gold ores, it is not ideal for some special types of gold ores. For example, gold ores containing a large amount of base metals such as copper, lead, and zinc, because these base metals will react with cyanide, consume a large amount of cyanide, thereby reducing the leaching rate of gold.

Time-consuming: In the process of gold extraction, it takes a long time to achieve a high gold recovery. Generally speaking, the cyanide leaching time takes 24-72 hours or even longer. This is because the reaction rate of gold with cyanide is relatively slow, and the existence and distribution of gold in the ore will also affect the leaching rate.

The above is an introduction to the characteristics and advantages and disadvantages of cyanide leaching gold extraction. In practical applications, in addition to cyanide leaching gold extraction, there are also flotation and gravity separation gold extraction processes. Therefore, it is necessary to comprehensively consider various factors according to the type and characteristics of gold ore and the actual situation of the enterprise to select a suitable gold extraction method. It is recommended to design a suitable process for it through mineral processing test analysis.