Improving cyanidation process of the gold ore containing sulfide compounds by water treatment and adding sodium ferrate

Usually, hydrometallurgy concept is applied in gold extraction process; where, water is the most widely used raw material. Therefore, the quality of water plays a very important role in the process. This work is focused mainly on the effect of water quality on gold leaching process; specifically, when additives were employed. Water in various qualities, alkaline substances (calcium hydroxide and sodium carbonate) and sodium cyanide were used to prepare the leaching solution. The gold ore was characterized by scanning electron microscope; the titration and atomic absorption spectroscopy methods were used to determine the amount of free cyanide and soluble gold, respectively. The results indicated that, by adding sodium ferrate to water and also consider a roasting stage in the process, dramatic change occurred in terms the solubility of gold (from 0.1 to 1.1 mg/l) and free cyanide (from 475 to 510 mg/l). The leaching rate was also affected when sodium ferrate was added to the used water.