Adding certain elements to the cyanide solution accelerates the dissolution of gold . Some researchers proved that, under certain conditions, adding a small amount of lead, thallium, bismuth and mercury, to improve the dissolution rate of gold. At least, the small amount of lead present can act as a synergist for the dissolution of gold (Figure 1). However, a large amount of lead, particularly at a high pH, ​​forms a Pb(CN) 2 film on the surface of the gold particles to suppress dissolution of gold. Fig.1 Effect of lead ion concentration on the dissolution rate of gold in 0.1% NaCN solution The presence of sulfur ions forms an insoluble film of gold sulfide on the surface of the gold particles, making gold difficult to dissolve. Alternatively, cyanide is consumed by cyanide to form a thiocyanate which does not dissolve the gold. Even a very low sulphide content in the solution (5 x 10 -4 %) significantly reduces the rate of gold dissolution (Figure 2). Fig. 2 Effect of Na 2 S concentration on the dissolution rate of gold and silver in 0.25% KCN solution When cyanidation flotation concentrates, xanthate and black medicine brought into the cyanide solution by the concentrate also reduce the dissolution rate of gold. When the concentration of xanthate in the cyanide solution of a gold-selecting plant in China increased from 33 mg ∕L to 110 mg/L, the cyanidation leaching rate of gold decreased from 74.2% to 55.6%. This is mainly because the surface of the gold particles is covered by a gold film of xanthogen. In order to improve the recovery rate of gold, the flotation concentrate or tailings must be removed before cyanidation. The deionization of concentrates is usually carried out after washing and concentration of concentrates after flotation to achieve the purpose of drug removal. The grinding grain size of a mine is 65%~0.074mm (200 mesh). After flotation, it is better to remove the xanthate and 2 # oil. After the flotation concentrate is detoxified by the cyclone, it is ground to overflow. The fineness is 98% to 100% 0.074mm (-200 days) and concentrated, and the flotation agent can be removed by 96%. Finally, the concentrate is sent to cyanide and gold, and the annual average leaching rate of gold is 90.57%. The carbon present in the ore and the hydroxide formed by silicon, aluminum , iron, etc. all have an adsorption effect, which is disadvantageous to the cyanidation operation. Disinfection Knife Holder,Sterilizing Knife Holder,Kitchen Knife Holder,Knife And Chopstick Holder Taizhou Huangyan New Vision Indsutry & Trading Co.,Ltd , https://www.super-factories.com