Other HCN Processes

Some alternate HCN processes that have been studied dining the 1990 s are  

None of these processes are believed to be used in commerical production in 2003. 

Dilute cyanide-water solutions at ambient temperature can exhibit a unique destructive action on stressed carbon steel. Cracks can develop in the metal in a very short time. The characteristic feature of the cracks is their transcrystalline course without formation of slip planes254. 

This is rather unique and is completely different from stress-corrosion cracking of unalloyed steel in alkaline solutions. In alkaline solutions the cracks always run between the crystals and usually only after plastic deformation. Normalized, stress-relieved steel is not usually subject to cracking254. 

Teflon is satisfactory for valve packing and gaskets in cold or ambient temperature HCN service. Above 45°C, HCN will penetrate the surface of Teflon , polymerize and destroy the material. Hypalon is probably the best material for hose linings for handling HCN at ambient temperature. Viton is better at somewhat higher temperatures254. 

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