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Greetings P2Techies:
I would appreciate pollution prevention ideas for
hexavalent chromium conversion coating.
Are there any possible substitutes (trivalent
chromium is not a possible substitute) or methods to reduce losses (no-rinse
coating processes?). I have never seen chromium recovered from the dilute
rinsewaters of chromate conversion coating and reused in the process, but I have
seen literature references. Is this alternative practical and
realistic? If so, what is the best technology?
Also, Does the chromium rinsed from the coated
metal contain significant quantities of trivalent chromium as well as hexavalent
chromium? In other words, during the conversion coating process does the
hexavalent chromium at the surface of the coated metal get converted to
trivalent chromium to any appreciable extent?
Thanks,
Rob Michalowicz
Chem Process & Environment Inc.
rob.michalowicz@sympatico.ca
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