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Excessive amount of caustic to treat effluent from pickling plant

March 6, 2017

Q. I need economical solution other than caustic to neutralize or handle effluent from pickling bath containing HCl and other impurities.

Do I need to use pickling inhibitor if we have acid regeneration plant.

waqar

waqar haider
- karach/pakistan
  ^- Privately contact this inquirer -^


March 2017

A. Hi wagar. There are more economical reagents to neutralize HCl, including lime or magnesium hydroxide; both are also safer than caustic, but each has limitations which must be worked around.

There are also ways to extend the life of the HCl bath, including better inhibitors (so less iron is consumed), and "acid extenders" (which precipitate the iron so the bath does not need to be dumped).

Regards,

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Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


March 7, 2017

Q. Thank you for the quick response. We are using pickling inhibitor from Rodine. Do I continue to need inhibitor if I go for acid life extenders?

waqar haider
chemical synergies - karachi, pakistan


March 2017

A. Hi Wagar. Sorry, although I would expect that the Rodine continues to provide useful inhibition, so acid isn't wasted on raw steel, I don't really know.

In as much as both the Rodine and the acid life extender are secret proprietaries, it may be hard for anyone but the supplier to offer answers about their compatibility and symbiotic effects. I'd suggest that you ask the manufacturer of the acid extender. Good luck.

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


March 10, 2017

A. There are several acid purification technology that can reduce the amount of caustic needed by 75-90%. You may want to investigate diffusion dialysis, acid retardation, and evaporation as a solution to this problem.

Lyle Kirman
Consultant - Cleveland Heights

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