Gold, Mercury, and Silver Extraction by Chemical and Physical Separation Methods

An agitation leaching method was used for gold extraction from Aghdareh mine samples. Mineralogical study showed that 58% of the gold particles were finer than 10 mu m. In addition 3% of the grade in the sample was related to refractory gold. Experiments results showed that at the optimum condition gold recovery was 91.8% and silver, and mercury recoveries were 41.5%, and 10.2%, respectively. After performing cyanidation tests for 6 different fractions, it was concluded that the most unleached gold particles exist in the fraction size finer than 25 mu m and about 5% of gold particles in the fraction size larger than 25 mu m was not leached. Therefore, further comminution was applied which increased by about 3.57% of gold recovery and about 5% of silver recovery. Further comminution did not affect the recovery of mercury. In order to increase the mercury recovery and prevent from amalgamation of gold by mercury particles, Knelson gravity concentrator was used. The tailing of gravity method was examined using cyanidation tests by considering the optimum conditions. According to the final results, using the combination of these methods, gold recovery is increased to 93.3% and the recovery of mercury increased to 42.1% while the recovery of silver is 42.17%, without noticeable change.