Extracting gold using coconut shell activated carbon is a common method used in the gold mining industry, especially in the carbon-in-pulp (CIP) and carbon-in-leach (CIL) processes. Here’s a step-by-step guide on how it is typically done:
- Crushing and Grinding
The gold ore is first crushed and ground to release the gold particles from the surrounding material.
- Leaching
The ground ore is then mixed with a cyanide solution. Cyanide is a chemical that binds with gold, forming a water-soluble complex. This process is called cyanidation.
- Adsorption
Coconut shell activated carbon is added to the cyanide solution. The activated carbon has a high surface area and porous structure, which makes it highly effective at adsorbing the gold-cyanide complex from the solution.
- Carbon-in-Pulp (CIP) or Carbon-in-Leach (CIL)
CIP: In this process, the leached pulp is transferred to tanks where activated carbon is added to adsorb the gold-cyanide complex.
CIL: Here, activated carbon is added directly to the leach tanks so that adsorption and leaching occur simultaneously.
- Carbon Stripping
Once the activated carbon is loaded with gold, it is separated from the pulp and washed to remove any adhering ore particles.
- Elution (Desorption)
The gold-loaded carbon is then treated with a hot, strong solution of sodium hydroxide and cyanide, which desorbs (removes) the gold from the carbon.
- Electro-winning or Zinc Precipitation
The gold-rich solution is then subjected to electro-winning or zinc precipitation to recover the gold. In electro-winning, an electric current is passed through the solution, causing the gold to deposit onto electrodes. In zinc precipitation, zinc powder is added to the solution, which precipitates the gold out.
- Smelting
The collected gold is then smelted at high temperatures to produce gold bullion.
Key Points to Consider:
Quality of Coconut Shell Activated Carbon: The effectiveness of gold adsorption depends on the quality of the activated carbon, which should have high hardness, high surface area, and optimal pore structure.
Control of Leaching Conditions: pH, cyanide concentration, and temperature should be carefully controlled to optimize gold recovery.
Carbon Management: Regular monitoring and management of the activated carbon are essential to ensure its continued effectiveness and longevity.
By following these steps, gold can be efficiently extracted using coconut shell activated carbon.
