(1995 Vol.27-No.2)Case Studies On The Use Of Fluidised Beds For The Heat Treatment Of Metals--Replacement Of Salt Baths With Fluidised Beds For General Toolroom Applications

摘要

Hardening, carburising and nitrocarburising of steels are heat treatment processes often carried out in baths of molten salts, such as nitrates, carbonates, cyanides, chlorides or caustics. Chemicals combined with high temperature means that there are often risks of explosions, bums and poisoning. Environmental problems also arise from the resulting vapours and the removal, transport and disposal of the toxic salts. Disposal of cyanide salt typically costs US$3,300 per tonne. The neutralisation of quench water, oil, cleaning water and washing water is usually carried out before discharge to the sewer, but unfortunately this is not always the case. Off-gases can be cleaned by passing the exhaust gases through a chemical scrubber, although this is also not always done.