Crushing:Â During this stage of the production process the size of ore from the mine is reduced to less than 5 inches. In addition, lime is added to achieve protective alkalinity.
Leaching:Â The crushed ore is moved to the leaching pad and is deposited in an area of 10,000 m2 to extract the metal from the rock using a solution of 200 ppm sodium cyanide giving an average consumption of 0.12 kg/ton of ore.
Subsequently the gold-rich solution is collected by the drain pipes placed on the geomembrane, which are protected by a 1.5 inch layer of crushed rock (“Overliner”) on the pad. This solution is sent to the PLS pool (pregnant leach solution).
ADR Plant â€“ Active carbon absorption:Â The rich solution from the PLS pool is pumped to 5 beds of activated carbon, where the metal values are adsorbed. The impoverished solution is discharged into the sludge tank, where the concentration of NaCN is adjusted to 200 ppm and then pumped into the leaching heaps, thus completing the closed cycle.
Refinery:Â The saturated electrolytic cathodes in the electrolytic cell are washed with pressurized water and then filtered. They are then mixed with fluxes and melted in an electric furnace at a temperature of 1,300 Â° C, then cast to get bars of dorÃ© of 60% to 70% purity.
Gases produced by smelting are conveyed by a hood and an extractor to a washing tower where the powders that have been extracted along with the gases during the smelting process are recovered. Gases completely cool and free from solids and any pollutants are released into the atmosphere.