Direct Carbon Leaching (DCL) is a modern technology for extracting precious metals such as gold from ores. This method achieves the purpose of gold extraction by directly adding activated carbon to the slurry containing cyanide so that gold ions are adsorbed by the activated carbon. Compared with the traditional cyanide gold extraction process, this method has the advantages of simple operation, low cost, and low environmental pollution. Therefore, it has been widely used and developed in the gold industry. Let's take a look at the process and advantages and disadvantages of direct carbon leaching of gold extraction.
Direct carbon leaching method of gold extraction uses the powerful adsorption properties of activated carbon to adsorb gold ions from the solution. The carbon leaching gold process mainly includes: ore pretreatment, cyanide leaching, activated carbon adsorption, desorption and recovery.
Ore pretreatment: The carbon leaching gold pretreatment process includes ore crushing and grinding, grading and screening, oxidation pretreatment to improve the solubility of gold, desludging and dehydration to reduce the influence of fine mud, slurry adjustment and acid adjustment to create suitable leaching conditions, and adding additives to improve the properties of the ore pulp to ensure effective leaching of gold and efficient adsorption of activated carbon.
Cyanide leaching: The pretreated ore is added to an aqueous solution containing cyanide. Under certain temperature and pH conditions, the cyanide and gold are dissolved by stirring, and the activated carbon is used to directly adsorb gold from the ore pulp to achieve gold extraction and recovery.
Activated carbon adsorption: Based on its highly developed internal pore structure and huge specific surface area, it can effectively attract and retain molecules in the fluid on its surface to form a monolayer or multilayer, thereby achieving the purpose of removing specific components in the fluid (such as organic matter, pigments, odor substances, etc.). In the process of gold extraction, activated carbon adsorption is to add activated carbon to the cyanide leaching solution. Because activated carbon has a highly developed pore structure and a huge specific surface area, it can efficiently adsorb the gold cyanide complex in the solution.
Desorption and recovery: By changing the temperature, pressure or chemical environment, the substances originally adsorbed on the surface of the activated carbon are released again. This process can restore the adsorption capacity of the activated carbon. Therefore, the activated carbon adsorbed with gold is desorbed from the activated carbon by thermal desorption or chemical desorption, and then the gold is recovered by electrolytic deposition or other methods.
High efficiency: Direct carbon leaching of gold extraction technology can complete the dissolution and adsorption of gold in a relatively short time, greatly shortening the production cycle and increasing the processing volume. Since cyanide leaching and activated carbon adsorption are carried out simultaneously, gold ions are adsorbed onto activated carbon as soon as they are formed, reducing the loss of gold.
Cost-effectiveness: Compared with the traditional two-step method (cyanide leaching followed by activated carbon adsorption), CIL technology simplifies the operation process, reduces equipment investment and maintenance costs, and reduces overall operating costs. In addition, due to the reduction of intermediate links, energy consumption can be saved, further reducing production costs.
Environmental protection: Although the use of cyanide has certain environmental risks, CIL technology can effectively control the use of cyanide, reduce wastewater discharge, and reduce the impact on the environment by optimizing the process flow. At the same time, activated carbon can be reused, reducing waste generation.
Strong adaptability: This technology is suitable for different types of gold ores, including ores with low gold grades. For difficult-to-treat sulfide ores, CIL technology can also be used after pretreatment to improve resource utilization.
Easy operation: The operation of CIL technology is relatively simple and easy to control and manage. Through the automated control system, precise control of leaching conditions such as pH, temperature, cyanide concentration, etc. can be achieved, ensuring the stability of the production process and product quality.
High recovery rate: Direct carbon leaching gold extraction technology can effectively extract gold from the ore pulp, and even fine-grained gold can be efficiently adsorbed on activated carbon, thereby increasing the gold recovery rate. This is of great significance to improving the economic benefits of the enterprise.
Flexibility: The CIL process can be flexibly adjusted according to the characteristics of the ore and production needs, such as by changing the amount of activated carbon added, leaching time and other parameters to optimize the process effect and meet different production goals.
Large consumption of activated carbon: During long-term use, some activated carbon will lose its activity and need to be replaced regularly, increasing production costs.
Large initial investment: Although CIL technology can reduce costs in the long run, it requires a large investment in equipment in the early stage, including the construction of special leaching tanks, activated carbon treatment systems, etc., which may put financial pressure on small mines.
Limited scope of application: Although CIL technology is applicable to many types of gold ores, for some special ores (such as ores containing a large amount of organic matter or iron minerals), it may encounter problems with poor adsorption selectivity, affecting the recovery rate of gold.
High safety and environmental protection requirements: The implementation of CIL technology requires strict compliance with safety and environmental protection regulations, which not only increases the management difficulty of enterprises, but also may face legal risks due to illegal operations.
The above is an introduction to the direct carbon leaching method for gold extraction. This method has obvious advantages in the field of gold extraction, but it also has certain limitations and challenges. When enterprises adopt CIL gold extraction technology, they need to comprehensively consider its advantages and disadvantages and take corresponding measures to ensure safe production and environmental protection.
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