Letter 14066

Chromate Recovery [Oklahoma] 

My question concerns recovery of a chrome bath once its gone bad. I have approx. 2500 gallons of chrome sitting in three holding tanks. All have 50 oz/gal CrO3 and about the same amount in sulfate.(1200 gallons in the 70oz/gal range). Trivalent is approx. 2%. These baths are old and have seen alot of use. Is it better to extract the water and have them hauled off and properly disposed or is possible to breath some life back into these baths? Our tanks size averages 1400 gal. so it would cost about $35,000 to make a new bath plus the cost of waste disposal($700 a barrel).

Any thoughts on this subject would be greatly appreciated.

Mark Osborne
- Oklahoma City, OK, USA

My thoughts are never dispose of chromium plating solution. It can be filtered, the trivalent chromium oxidized, the iron removed, etc. Look into porous pots or dialysis membranes.

 
Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

Please double check your sulfate concentrations. If you really have 50 oz/gal of sulfate, you are going to have to precipitate 99% of it with barium in order to make a plating bath with the correct ratio. This will be costly, time consuming and will generate a huge sludge volume that will require disposal as a hazardous waste.

If the sulfate values are really that high, I would suggest that you send the old solution to a reclaimer. It may cost nearly as much as other forms of disposal, but you may get a reasnonable credit back for the chromium, and you won't have the ongoing liability for the waste.

Lyle Kirman
water treatment systems - Cleveland, Ohio

It is also possible to employ a chrome purification system to greatly reduce the waste produced. This could be of benefit to you.

Kirsty Goepel
- England

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