Cyanidation method is a commonly used gold extraction method for ore containing low content of gold. Generally, leaching is needed to extract gold. Heap leaching technology is suitable for low-grade ore containing gold. The ore is piled up in small heaps and is sprayed with a dilute solution containing sodium cyanide. Gold is extracted from cyanide solution by zinc powder replacement method or activated carbon adsorption method. Generally, the leaching rate is slow.
The difficulty with the leaching process is that complete leaching is not easy to achieve. In order to speed up the leaching process and improve the leaching rate, usually together with oxidation and leaching process, such as sodium hypochlorite oxidizing pre-treatment, then heap leaching process, etc. is adopted
Thiourea leaching method is a common gold extraction method used for gold bearing ore with a certain degree of oxidation. Thiourea is a white powder with a melting point of 238℃. It is highly poisoning, If it is in contact with the skin, it will cause allergy and should be collected as much as possible.
Thiourea extract gold leaching process is complex. It also needs oxidizing pretreatment. Cyanide leaching must be done after thiourea leaching, and activated carbon adsorption method is usually used to recover gold from the leaching liquid. The thiourea leaching rate is higher than that of cyanide leaching.
When compared to cyanidation method and thiourea leaching method, thiourea gold leaching process has advantages, such as simple technology, less reagent consumption, and is more friendly to the environment, but it also has disadvantages, such as relatively low gold leaching rate, higher cost and more complicated operation process.
The thiourea gold leaching process is often used for the extraction of gold from gold-bearing ore with a certain degree of oxidation. Choosing the proper gold leaching method is determined by the technology index of ore, the ore composition and the specific conditions of production. In order to make the process better, scientific selection and reasonable combination of different leaching methods should be adopted.
