Function Of Activated Carbon For Gold Mining

Activated carbon is widely used in the absorption of gold cyanide complexes in gold processing. This process can be applied to the clear solution through a fluidized bed column or participate in the process of leaching on the tank and the separation of carbon. Activated carbon in the cyanide process gold or commonly referred to as activated charcoal is charcoal made ​​from coconut shell charcoal, charcoal or wood or coal. The most widely used is granular activated carbon from coconut shell charcoal. With specific processing of the activation process such as treatment with high pressure and temperature, can be obtained activated carbon has a surface in the area. Glanural activated carbon derived from coconut shells are produced by pirolis with temperature 600-900 degrees Celsius by using an inert gas (argon or nitrogen) or by oxidation or combustion.
Adsorption of gold complexes (especially ion disianoaurat) on activated carbon is the basis of modern techniques for gold extraction process. This process is very effective and has become a major factor in improving the productivity of the gold mining industry over the last 25 years (S., Mansooreh, Tahereh Kaghazchi, 2007). Carbon is very actively used in the process of recovery of dissolved gold, either by introducing direct to the CIL (carbon-in-leach) or CIP (carbon-in-pulp) tanks after leaching. Activated carbon adsorbs dissolved gold from gold leach pulp complex to be absorbed through the pores of the carbon.The most cost-effective process is to create adsorption of the dissolved gold onto activated carbon, resulting in an Easier solid-solid separation based on size To Achieve this ore particles must typically be Smaller than 100 μm while the carbon particles must be larger than 500 μm. Adsorption is achieved by Contacting the activated carbon with the agitated pulp. This can be done while the gold is still being leached with the CIL-process, or following leaching with the CIP-process. The CIL-process offers the advantage of Countering the adsorption of gold on carbonaceous or shale ore particles, but is more expensive due to less efficient adsorption, Increased gold inventory and Increased fouling and abrasion of the carbon. 
Activated carbon in contact with a pulp containing gold can typically recover more than 99.5% of the gold in the solution in 8 to 24 hours, Depending on the reactivity of the carbon, the amount of carbon used and the mixer's efficiency. The loaded carbon is then separated from the pulp by water or screens That are swept hydrodynamically, thus Preventing blinding by the near sized carbon particles. The pulp residue is then either thickened to separate the cyanide containing solution for recovery / destruction of the cyanide, or sent directly to the tailings storage facility from the which the cyanide containing solution is recycled to the leach plant. 
       The gold adsorbed on the activated carbon is recovered from the carbon by elution, typically with a hot caustic aqueous cyanide solution. Gold was obtained by the method of cementation or by elektrorefining of the solution, while the carbon can be reused. Activated carbon can be reused by washing with dilute hydrochloric acid (HCl) to remove metallic impurity and neutralized with caustic soda. Reactivation is then performed first using a rotary kiln at a temperature of 730 degrees Celsius for 20 minutes. Generally, 10% of carbon lost in the process due to abrasion. During the process, the performance of carbon has decreased so that the efficiency of carbon sequestration need to be monitored and if necessary the addition of new carbon. In traditional mining usually carbon that has been filled with gold complexes directly in the fuel. Dust from the burning of carbon was then taken to be melted. Contained metal can be purified directly. This is done because of cost considerations and technology.When carbon is not used to adsorb the gold dissolved in the above-Mentioned leach slurry, the gold bearing solution must be separated from the solids components utilizing filtration or thickening units. The resultant solution, Referred to as pregnant solution, is subjected to Further treatment (other than by carbon absorption) to recover the dissolved gold