Gold Recovery Methods

The recovery of gold from gold-bearing ores depends largely on the nature of the deposit, the mineralogy of the ore and the distribution of gold in the ore. The methods used for the recovery of gold consist of the following unit operations:

Gravity Concentration methods are systems which use gold’s high density to capture the precious metal. Gravity based equipment includes jiggs, spirals, sluices and tables. Gravity systems are often the lowest cost system, but only a certain part of the gold is usually coarse enough to be recovered with gravity systems. It is common that ores be processed by two methods - gravity is used to remove the coarser gold from an ore and afterward the ore is processed by cyanide to recover the fine particles of gold and silver. Gravity concentration methods are the ones most commonly used by the individual prospector.

Hydrometallurgical methods are normally employed for recovery of gold from oxidized deposits (heap leach), low grade sulRde ores (cyanidation, carbon-in-pulp (CIP), carbon-in-leach (CIL)) and refractory gold ores (autoclave, biological decomposition followed by cyanidation).

A combination of roasting and hydro-metallurgical route is used for highly refractory gold ores (carbonaceous , gold ores) and the ores that contain impurities that result in a high consumption of cyanide, which have to be removed before cyanidation.

The flotation method is a widely used technique for the recovery of gold from gold-containing copper ores, base metal ores, copper}nickel ores, platinum group ores and many other ores where other processes are not applicable. Flotation is also used for the removal of interfering impurities before hydrometallurgical treatment.Flotation is considered to be the most cost-effective method for concentrating gold.