Metal finishing Q&As since 1989

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Need non-hazardous "chromating"

Hello,

I am working on a project where we are trying to start up a chromating line. However we are mainly a manufacturing company and we do not have emissions certificates or things like that which would allow us to use Hexavalent Chrome, or other stinky or hard to dispose of chemicals. Currently we pump our wastewater into a tank and have it drained every other week. The company that drains it, process is it and sends the solid extract to a landfill.

We need to etch/descale and deoxidize our aluminum from heat treating, and chromate it.

So my question is: are there any non-hazardous chromating procedures that could accomplish all of this (descale/deox/chromate)?

Thank you,

Dan N [last name deleted for privacy by Editor]
Manufacturing - Telford, Shropshire, England
2004

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There has been tremendous progress in this in the last few years, Dan, in finishes that do not include hexavalent chromium on them. Four manufacturers are licensed by the U.S. Navy to offer the TCP replacement process: Henkel, Luster-On, Metalast and Sur-Tec. Non-chrome alternatives are available from Chemetall, International Chemical Products and Sanchem.

Any of these manufacturers can probably offer you cleaning, etching, and desmut products as well. But whatever chemistry you use, you cannot remove dirt and oils and greases from the parts without being left with the problem of what to do with the dirt and oils and greases. Similarly, when you etch and desmut, you are removing copper and other alloying materials from the surface of the aluminum and are left with them in your process tanks. Here is the U.S. you would have to have permitted exhaust ventilation and wastewater treatment. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey