From the reaction formula 2Au+4CN - +O 2 +2H 2 O=====2Au(CN) 2 - +H 2 O 2 +2OH - In industrial production practice, c(CN - )/c(O 2 ) fluctuates within the range of 4.6-6.8, which is in good agreement with the theoretical value. At this time, the maximum gold cyanide rate will be obtained. Brake Pads For Chery,Chery Brake Pads,Chery Car Brake Disc,Chery Brake Shoes Ningxia Rossking Auto , https://www.rosskingauto.com
It can be seen that the dissolution rate of gold is twice the rate of consumption of oxygen and is half the rate of consumption of cyanide ions. When the concentration c (CN - ) of cyanide in the solution is very low, the rate of gold dissolution only changes with the cyanide concentration c (CN - ). When the concentration of cyanide in the solution is high, the rate of gold dissolution depends on the concentration of oxygen. When the cyanide concentration is in transition from cyanide diffusion control to oxygen diffusion control, the ultimate gold dissolution rate will be obtained.
Ying Ying Gu (1994) in the dynamic model of gold dissolution in a cyanide simultaneously derived gold cyanide process, when the maximum speed of cyanide in cyanide solution free cyanide ion CN - and concentration The optimal ratio of free oxygen O 2 concentration is:
The significance of this ratio is that the concentration of O 2 or CN - in the solution is important for the cyanide solution. The concentration of the two should meet a certain ratio to maximize the dissolution rate of gold. . If you are only working to increase the solution in production. The concentration of (O 2 ), that is, inflated, and the lack of free cyanide in the solution, the dissolution rate of gold does not reach a maximum; on the contrary, only the cyanide concentration is increased. (CN - ), without proper inflation, it is clear that excess cyanide is just a waste.
For example, at room temperature and standard atmospheric pressure, 8.2 mol of O 2 can be dissolved in 1 L of water, which corresponds to a mass concentration of oxygen of 0.27 × 10 -3 mol/L. Therefore, the limit velocity of gold dissolution should occur when the KCN concentration is equal to 6 × 0.27 × 10 -3 mol / L or the mass fraction is 0.01%.