The sulphur dioxide-air method is a new method for purifying cyanide-containing sewage. The chemical principle is as follows: Versatile Custom Paperboard Boxes And Folding Cartons Folding Paperboard Boxes,Paperboard Boxes Packaging,Corrugated Paperboard Boxes Jiangsu Hualong Printing Co.;Ltd , https://www.hlpackingtop.com
CN - +SO 2 +O 2 +H 2 O→CNO - +H 2 SO 4
This method is at room temperature, when 7 ~ 10 pH =, with sulfur dioxide gas, air, lime, and the small amount of copper sulfate was added as catalyst, for 30 minutes. The method does not require high temperature and has no obvious influence in the temperature range of 4 to 60 °C.
The sequential method is a metal cyanide removal: Zn> Fe> Ni> Cu . The treatment uses sulfur dioxide-air as a reducing agent to reduce the ferricyanide complex to Fe 2+ to form an insoluble salt of MeFe(CN) 6 •xH 2 O (where Me represents Cu, Zn, Ni) and precipitate. After the iron is removed, the residual Cu, Zn, Ni, etc. will eventually become a hydroxide solid and precipitate.
The advantage of the sulphur dioxide-air process is that free or complex cyanide, especially the ferricyanide complex, can be removed by oxidation. In the treated waste liquid, the total cyanide energy can be reduced to less than 1 mg/L, and the cyanide effect is better. The anti-celebration speed is fast, and the reaction can be performed at a high speed at room temperature. The oxidation sequence of cyanide is: cyanide ion> cyanide ion> thiocyanate ion. It is generally considered that CNS is non - toxic and does not require oxidation. If the operating conditions are well controlled and only oxidized to cyanide ions, the consumption of the agent can be reduced. The disadvantage of this method is that people do not have recycled components. China's sulfur dioxide gas source is a problem. If the thiocyanate decomposition is poor, so the ore is a sulfide ore, or the beneficiation process is flotation cyanidation, this method should not be used.