Technological characterization of riacho dos machados gold ore for cyanide leaching and study of the utilization of oxidising agents

This work evaluates the behavior in the cyanide leaching of primary gold ore from Riacho dos Machados, central Brazil. The parameters studied were: extraction of gold/silver in different ore sizes to determine the exposition of precious metals; rate of extraction in bottle roll tests with crushed and ground ores; and the effect of addition of oxidising agents (air, oxygen and hydrogen peroxide) on gold/silver leaching. The run of mine ore contains about 7 ppm of gold and 2 ppm of silver. The gold/silver particles are of microscopic and submicroscopic sizes and 90% of the gold was extractable. The use of oxygen and hydrogen peroxide mixed with air increased the rate of gold dissolution.