Huang Zhucheng

Influence of copper minerals on cyanide leaching of gold

The paper thermodynamically examined the behavior of various copper minerals in cyanide solutions and investigated the influence of copper minerals on cyanide leaching of gold. In elucidating the influence of copper minerals on cyanide leaching of gold, copper minerals were classified into two types according to their solubility in cyanide solutions by proposing two concepts, cyaniding easily soluble copper (ECu) and cyaniding insoluble copper. The former involves copper occurrence in metal, oxides and secondary sulfides, and the latter refers mainly to primary sulfides. Experimental results show that not all the total copper in an ore affected cyanide leaching of gold, while cyaniding easily soluble copper turns out to be the decisive factor that interferes with gold cyanidation by causing decrease in gold cyanidation recovery and increase in cyanide consumption. When cyaniding easily soluble copper content (wE(Cu)) lies in the range of 0–0.25%, it linearly affects gold cyanidation recovery (R) as well as cyanide consumption (mc). The regression equations have been worked out to be R(%)=94.177 5−142.735 7 wE(Cu) with a correlation coefficient of −0.902 and mc=5.590 7 +33.572 9 wE(Cu) with a correlation coefficient of 0.945, respectively.

Selective recovery of silver from an acidic solution by cementation with copper

An acidic solution containing 280 mg/l silver and others was treated. In order to selectively recover silver without losing other metallic elements from the solution, cementation was adopted with metallic copper. The kinetics of cementation reaction and copper dissolution and mechanism of copper consumption were studied. The results indicated that the rate of cementation reaction and copper consumption were markedly increased with the increase of temperature. For the same cementation recovery of silver, copper consumption at elevated temperature was much higher than that at ambient temperature. Cementation rate and copper consumption rate also increased with the increase of stirring velocity, while copper consumption at different stirring velocity for the same recovery of silver was almost not different. Studies on the chemical mechanism of copper consumption showed that Fe3+ and residual leaching additive RH in the solution were the main factors that caused extra copper consumption in acidic solutions.