Under acidic conditions, water is simply cyanide cyanide, the cyanide complexes and metal sulfide cyanate easy to parse volatile hydrocyanic acid gas, and then collected and absorbed by the lye. Therefore, this method can recover cyanide and purify cyanide-containing sewage. Financial Equipment Part,Precision Hardware Parts Processing,Zinc Aluminum Alloy Die Casting Plant,Hardware Cnc Lathe Processing Dongguan Shangjie Precision Hardware Co., Ltd , https://www.shangjiecnc.com
The process of regenerating and recovering cyanide by the sulfuric acid method is as follows:
The simple cyanide, complex cyanide, and thiocyanate in the acidification stage are dissolved and decomposed to form HCN gas:
2NaCN+H 2 SO 4 →Na 2 SO 4 +2HCN↑
NaZn(CN) 4 +2H 2 SO 4 →ZnSO 4 + Na 2 SO 4 +4HCN↑
2Na 2 Cu(CN) 3 +2H 2 SO 4 →Cu 2 (CN) 2 ↓+2Na 2 SO 4 +4HCN↑
2Na 3 Cu(CNS)(CN) 3 +3H 2 SO 4 →Cu 2 (CNS) 2 ↓+3Na 2 SO 4 +6HCN↑
In the stripping stage, the acidified sewage is fully exposed to the air, and the air stream takes away the volatile HCN gas stream generated by the above reaction, so that the cyanide purification rate in the sewage can reach 96% or more.
The hydrocyanic acid gas volatilized in the absorption stage is taken away by the air stream, neutralized with sodium hydroxide solution, and recovered by sodium cyanide. The reaction is as follows:
NaOH+HCN→NaCN+H 2 O
After the precipitation and filtration stage is acidified, after the stripping treatment, there is a milky white precipitate in the waste liquid, such as Cu 2 (CNS) 2 , Cu 2 (CN) 2 , AgCNS and the like, which are recovered by concentration filtration. The overflow or filtrate is discharged after being treated.