3.8 Gold Recovery

Typical Carbon-in-Leach flow diagram

The process flow diagram illustrates a typical Carbon-in-Leach (CIL) circuit used to recover gold from mined ores. The ore is crushed and milled and the resulting classified ore/water slurry is thickened before passing to a series of CIL mechanically agitated contactors.

In the CIL contactors gold is leached from the ore and is adsorbed onto Filtracarb CL50, which is present in each of the stages. Interstage screens are employed to allow the pulp to flow from one stage to another while at the same time retaining the Filtracarb CL50 in the individual contactors. Filtracarb CL50 is transferred counter-current to the pulp flow. Loaded Filtracarb CL50 is transferred, after acid washing to remove mineral contaminants, to the elution column. Gold is eluted from the loaded Filtracarb CL50 using a concentrated sodium cyanide/sodium hydroxide at elevated temperature and pressure. The resulting gold solution is passed to an electrowinning cell where gold is deposited onto steel cathodes. The loaded cathodes are removed, processed and smelted to produce gold bullion (Doré).

Following regeneration, Filtracarb CL50 is screened and returned to the adsorption circuit.

Key product features are: Ability to achieve high gold loadings from low gold concentration pulps/solutions High rate of gold loading enabling optimum inventories to be readily achieved Maximum resistance to mechanical attrition, minimising gold losses Low platelet count optimising interstage screening efficiency, thus minimising gold loss Stringent particle size distribution specifications, to control amount of undersize material.

A Carbon-In-Leach facility

Typical Product Properties