The carbon-in-pulp process involves crushing and finely grinding ore. The gold pulp is mixed with a sodium cyanide solution and comes into contact with activated carbon in several adsorption blending tanks. Use of a countercurrent circulation system for the solution and the activated carbon is useful for maximising the efficiency of gold mining.
The carbon-in-solution process is similar to the carbon-in-pulp process, but the former involves simultaneous leaching and adsorption. This carbon adsorption technology is mainly used to process ores rich in natural sorbents.
The carbon-in-column process involves washing crushed gold-bearing ore with a cyanide solution which then flows upward through a cascade of sorption columns at a rate supporting a hot bed.