In the process of extracting gold and other precious metals, mineral recovery is measured in ounces, so a difference in grams can represent a huge difference in the efficiency of all the process.

Activated carbon is used in the extraction of gold after the cyanidation, usually in tanks called carbon columns which are loaded from the bottom with the pregnant solution to avoid the compaction of the coal at the bottom, these columns can be of different sizes and amounts, usually they are arranged in circuits between four and five columns, and there can be more than one column circuit.

Activated carbon is an organic material that has a porous structure with a large surface area once is activated in his manufacturing process, (pores below 2 nm and between 500 and 2500 m2 / g).

Activated carbon made from coconut husk is the most used currently, and has characteristics such as absorption capacity, wear resistance, reactivation and mechanical strength.

 

There are some factors that can affect the efficiency of the absorption of gold in activated carbon, some of them are:

  • Temperature: The absorption of gold is exothermic so the load capacity decreases when the temperature increases.
  • Concentration of cyanide: When the concentration of free cyanide increases the loading speed of gold in the coal decrease.
  • Concentration of the gold in the solution: The speed of absorption of the gold and the load balance increase, when the gold content in the solution increases.
  • pH: The lower the pH, the higher the absorption speed and the load capacity.
  • Ionic strength: The speed of absorption and the load capacity increase with increasing ionic strength
  • The loading capacity of gold increases in the presence of calcium cations, magnesium, hydrogen, lithium, sodium and potassium.

 

Another important factor to deal with, is that the absorption of other metals in activated carbon causes them to compete with the gold for the active pore sites, so it is important to know the concentration of each of this metals, the properties of the carbon that we have, and the general conditions of the solution.

 

 

Tahnk you for reading, best regards.