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As we all known, the process of extracting gold using cyanide as gold extraction agent is called cyanidation gold extraction, which is the main method for extracting gold from ore or concentrate. According to research and practice, cyanide gold extraction is not only efficient, but also low in cost and simple in operation. However, a major disadvantage of cyanide gold extraction is that cyanide is highly toxic, pollutes the environment and is slow to immerse gold. It is easily affected by impurities such as copper, iron, lead, zinc and arsenic. Therefore, the recovery rate is usually low. The commonly used gold extraction agents are NaCN, KCN, NH4CN, CaCN2. With the development and progress of modern technology. The low-toxic chemical gold extraction agent gradually replaces cyanide. Just like environmentally CNLITE gold leaching reagent, its most important feature is low toxicity, high environmental protection, high leaching rate and recovery rate, and wide application range, so which gold extraction processes can be applied with low-toxic CNLITE chemical gold extraction agent?
In general, non-toxic gold extraction agents can be used in place of sodium cyanide in the Gold Mine All Sliming Cyanidation CIP Process (CIP), Gold Mine All Sliming Cyanidation CIP Process (CIL), heap leaching, pool leaching and All Sliming Zinc Powder Replacement. Taking the carbon leaching method and the carbon slurry method as example, the carbon leaching method is characterized by simultaneous gold leaching and adsorption, and the number of leaching stages is generally 6-10 stages. During the leaching process, the fineness of the grinding product is moderate. Then add a certain amount of high-efficiency environmental gold extraction agent to ensure the high leaching rate. The carbon slurry method is a gold extraction method for directly adsorbing gold from the cyanide leaching slurry by using granular activated carbon, which not only saves the solid-liquid separation of the conventional process, but also facilitates the improvement of cyanide leaching rate. The production process of the carbon slurry method includes: grinding, cyanide leaching, pretreatment, activated carbon adsorption, carbon slurry separation, activated carbon desorption, electrodeposition and regeneration of decarbonized carbon. In industrial production, lime is commonly used as a protective base to maintain pH between 9 and 10, the slurry concentration is about 40%, and stirring leaching time is 24 hours or more. In this process, the low-toxic and environmental gold extraction agent is mainly used for cyanidation to replace the traditional cyanide gold extraction agent.
It can be concluded from above two gold extraction processes that as long as the chemical reaction appears between the solid gold particles and the oxygen-containing cyanide solution, sodium cyanide can be substituted by CNLITE non-toxic and environmental gold extraction agent. Dissolution is completed in two stages. In the first stage, hydrogen is produced while dissolving gold. In the second stage, hydrogen peroxide and cyanide re-dissolve gold, and the whole reaction can be completed by the above two steps. The principle of low-toxic gold extraction agent and cyanide gold extraction is similar, so gold extraction agent can replace cyanide, but since the by-product produced in the chemical reaction can further catalyze the chemical reaction, the recovery rate of gold is greatly improved, at the same time, the substance produced after the chemical reaction is degraded and eco-friendly environmental. The pollution is extremely low, so the application range of low-toxic gold extraction agents become more and more extensive.
In addition to the above-mentioned heap leaching, pool immersion and other processes, the new high-efficiency, eco-friendly environmental gold extraction process is also suitable for industrial production which will be the research focus of making full use of low-grade and refractory gold mines in the future. In this process, it is necessary to use relevant gold extraction agents to assist in the completion of gold withdrawal, and with the increasing environmental protection calls in recent years, the environmental protection requirements of the society, enterprises and the public are more stringent, and the low-toxic gold extraction agent is developed because of the environmental protection and high recovery rate. The prospects are broad and the scope of application will gradually expand.
Why the eco-friendly environmental gold extraction process favored by experts? With the implementation of new Environmental Protection Law, the regulations on environmental protection are more stringent, and the penalties for environmental damage are more severe. Recently, China has planned to levy an environmental protection tax. In the critical period of transforming the mode of economic development, the replacement of cyanide with gold extraction agents is in line with general trend of China’s economic development.
Although China is very mature in the treatment technology of cyanide waste liquid, the removal rate of cyanide pollution can reach 99%. However, once cyanide leaks, it will have serious consequences. Whether it is safe or eco-friendly environmental, low-cyanide gold technology has a unique advantage.
If the eco-friendly environmental gold extraction agents can be applied to a large scale industrial production, so the cyanide gold extraction method is replaced, the use of cyanide can be greatly reduced.
In the aspect of technology, the cyanide gold extraction method also encounters a technical bottleneck. For the difficult selection of metallurgical ore resources, the direct use of cyanidation to extract gold has become powerless, and it is urgent to develop a new gold extraction process to replace the cyanidation process. At present, the eco-friendly environmental gold extraction agents have been developed, and the immersion gold rate is fast, non-toxic, and insensitive to impurities, and has a very large potential for replacing cyanide.
Although the eco-friendly environmental gold extraction agent isn’t mature enough, there are still some problems to be solved in terms of production cost and industrial application, but the eco-friendly environmental gold extraction agent has begun to show advantages such as safety, environmental protection and adaptability. Although the development of eco-friendly environmental gold extraction agent is currently difficult now, but it will be the general development direction of gold mining technology.