The carbon leaching method (CIL) is a gold extraction process where leaching and adsorption occur simultaneously, thus eliminating the need for a separate stirring tank and reducing investment costs.
The carbon leaching process is particularly effective for treating low sulfur oxidized ores with significant slurry content, but it is not suitable for high silver gold ores.
The best conditions for the carbon leach method include a pH of 10-11, sodium cyanide concentration of at least 0.015%, activated carbon particle size of 1-3.35mm, and leach pulp concentration of 40-45%.
The main equipment includes crushers, belt conveyors, vibrating screens, ball mills, classifiers, dust removal systems, thickeners, slurry pumps, leaching tanks, adsorption tanks, and more.
The leaching process typically involves 6 to 10 stages of leaching and adsorption to effectively extract gold.
Cyanide is used to leach gold and silver from the ore, forming a gold-silver cyanide complex, while lime is added to maintain a high pH to prevent toxic gas generation.
Coconut shell activated carbon is commonly used due to its excellent adsorption performance and wear resistance.
The high temperature and pressure desorption process typically uses an aqueous solution of 0.1% sodium cyanide and 1% sodium hydroxide at temperatures of 150-170°C and pressures of 0.35 MPa.
Advantages include shortened leaching time, increased leaching rate of gold and silver, reduced cyanide consumption, and effective processing of minerals containing oxygen-consuming minerals.
The process is designed to reduce cyanide consumption and improve efficiency, contributing to more sustainable mining practices, although safety measures are necessary to handle cyanides.
In automated carbon leaching plants, hydrogen cyanide gas detectors are installed in the leaching and adsorption areas to ensure safety.
No, the carbon leaching process is not suitable for high silver gold ores; the gold/silver ratio should not exceed 1:5.
The gold content of the suspension solution after adsorption typically ranges from 0.01 to 0.03 g/m³.
It is mainly used for processing low sulfur oxidized minerals, electrolytic extraction by desorption, carbon pickling, thermal regeneration, chemical preparation, and wastewater treatment.
The high temperature and pressure desorption method reduces chemical consumption by using less sodium cyanide and sodium hydroxide, leading to faster desorption rates.
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