Metal finishing Q&As since 1989
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Simply Rinsing Zinc Diecastings Seems to Contaminate the Water with Zinc
Q. We are using a resin from Imprex to impregnate aluminum diecastings which seals the porosity. Does anyone know if diecast aluminum will emit small amounts of metals into the hot rinse water? Our castings can have up to 3% zinc and for some reason, we are getting zinc in our rinsewater. The tank is a 500 gallon tank which is dumped weekly. During a week, we send over 100,000 diecastings thru the system weighing about 2 pounds each with lots of surface area.
We can't explain the presence of 3 PPM of zinc any other way. There is no zinc in the resin material. Our sewer permit does not allow this amount of zinc to go to sewer so we will have to treat or haul this additional fluid. Any ideas?
- Fletcher, North Carolina
2000
A. I would analyze the used resin for zinc to see if zinc is being dissolved during impregnation.
Tom Pullizzi
Falls Township, Pennsylvania
2000
A. Hi Ray.
If Tom's suggestion doesn't locate the impregnation process as the source of the zinc, I would suggest collecting a beaker [beakers on
eBay or
Amazon] of the wastewater and analyzing half of it before and half of it after filtering it through a Watman filter to determine whether the zinc is entering as dust & particles or whether it is actually dissolved. Good luck.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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