Gold Recovery after Elution

Recovery: Once elution is performed, the obtained solution can be treated by electrowinning. Electrolytic cells have steel wool as cathodes and stainless steel as anodes. Steel wool is smelted and gold is obtained like bullion. Some typical parameters of electrowinning are current, 0.3-0.8 amp/dm², 0.4-0.8 kw-hr/oz. The final electrolyte is recycled to the elution step.

Variables Affecting Gold Recovery

Gold recovery by ion exchange resins by a RIP process can be affected by the following variables:

Resin concentration. If the amount of resin added is high each time, the gold extraction rate trends to increase. Ideal 7-10% by volume.

Resin particle size. The smallest sizes give better loading, but excessively small are inappropriate. A good size can be 0.5-0.7 mm.

Temperature. Higher temperatures give better recoveries. The maximum temperature must be in the range 40 to 60 ^oC.

Gold concentration. Higher concentration gives better extraction rate. Maybe, promotes good interaction with functional groups of resins.

pH. The pH effect is depended of the functional group, but the optimum pH in the range 7-10.

Solution composition. Silver is extracted faster at the beginning of the process and the gold improves its kinetic immediately. Some metals such as copper, zinc, nickel, cobalt and iron are loaded onto the resin. Some anions such as carbonate, chloride, sulphate and cyanide compete with aurocyanide ions, and consequently, affect unfavorably the gold extraction.