1. Complex ore properties affect adsorption efficiency

The CIL process is sensitive to ore composition. If the ore contains clay minerals or organic matter, it is easy to increase the viscosity of the ore pulp, which will hinder the contact between the activated carbon and the gold cyanide complex. In addition, metal impurities such as copper and zinc in the ore will react with cyanide, which will not only increase the consumption of reagents, but also may form complexes to pollute the surface of the activated carbon and reduce the adsorption efficiency.

2. Large fluctuations in leaching rate

The control of dissolved oxygen content, cyanide concentration and pH value in the leaching tank directly affects the leaching rate of gold. Due to backward automated monitoring equipment, some mines are difficult to adjust parameters in real time, resulting in a fluctuation range of more than 5% in the leaching rate. For example, when the pH value deviates from the reasonable range of 8-10, it will significantly inhibit the cyanidation reaction.

3. Management difficulties of activated carbon circulation system

Activated carbon is prone to the following problems in the adsorption-desorption cycle:

‌Mechanical loss‌: Carbon particles collide and break in the stirring tank, resulting in a reduction in adsorption surface area, and the annual loss rate can reach 10%-15%‌;

‌Low regeneration efficiency‌: If the high-temperature regeneration furnace is improperly controlled (＞750℃), the carbon pore structure will collapse, and the adsorption capacity will drop by more than 30% after regeneration‌;

‌Microbial contamination‌: Microorganisms such as thiobacillus in the slurry form biofilms on the carbon surface, hindering the diffusion of gold ions‌.

4. Equipment corrosion and high maintenance costs

Sodium cyanide solution in the CIL production line seriously corrodes carbon steel equipment, especially the agitator blades, pipeline welds and other parts, with an average annual corrosion rate of 1.5mm/year‌23. Some companies use ordinary steel to reduce costs, but instead increase the frequency of equipment replacement and increase the comprehensive operation and maintenance costs by 30%-40%‌.

Conclusion

The problems in gold mine CIL production involve multiple dimensions such as process optimization, equipment upgrade, and safety control. Comprehensive measures such as ore pre-selection (such as flotation removal), intelligent control system application (such as pH/ORP online monitoring), and high-performance material replacement (such as epoxy resin coated pipes) are needed to improve quality and efficiency. Enterprises should establish a full-process risk management system to fulfill their safety production and environmental protection responsibilities while ensuring production efficiency.