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How to remove nickel and chromium from pickling operation

Does anyone know how to remove nickel and chromium from rinse water in a pickling operation.

Tom Holzinger
steel wire manufacturing - Huntington, Indiana
2004

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I would add a little bit of hydrated lime [affil links], elevate the pH to something like 10.5 with sodium hydroxide, then floc out the precipitated solids and see what you get. If one of the dissolved metal numbers was over the permissible discharge limit, I would then try a series of jar tests, varying the final precipitation pH in 0.2 pH unit increments from 9.5 to 11. If none of these tests worked, I would try a final pH in the mid 9 range, and a precipitant like sodium sulfide or DTC. A pickling waste should not contain hexavalent chromium, so a chrome reduction step is unnecessary.

The problem is that these two metals have very different optimum precipitation pH's - Cr at about 9, Ni at about 11. Treating a mixture of the two therefore involves a compromise, if hydroxide precipitation is the only mechanism of metal removal.

Dave Wichern
Consultant - The Bronx, New York
2004

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Conventional hydroxide precipitation/settling will remove your metals. Depending on your local regs, you may need improved precipitation/solids removal.

Jeffrey Holmes, CEF
Spartanburg, South Carolina
2004

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2004

If the metal concentrations are relatively low(< 50 mg/L), you may want to consider using ion exchange to selectively remove the metals and concentrate them into a small volume. This type of system is usually has a much lower operating cost than a conventional treatment system.

The small volume of regeneration waste could either be batch treated, or hauled off-site to a licensed treatment/disposal contractor.

Lyle Kirman
consultant - Cleveland Heights, Ohio

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2005

Yes, you can use the most powerful solution and the cheapest, ECP(Electro-Catalytic Precipitation).

For details and solution, contact me.

Please send us water analysis, flow rate and discharge quality requirements.

Regards

Damian Dinu
- Constanta, Romania