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Black Nickel Deposit

We electrowin Nickel from a Nickel sulphate solution at a current density of 250-400 Amps/Mt2 and agitation promoted by mechanical stirring. Sometimes we get a black sometimes powdery deposit over the Nickel. It seems to be a Nickel compound because when analyzed by ICP it does not show other metals than Na (from pH control) and Ni. When scrapped off and passed under a magnet it shows to be magnetic. What could it be?

Alfonso Benavides
- Corpus Christi, Texas


Dear Mr. Benevides:

When you electrowin this nickel, no doubt you will be codepositing other components. What you might be seeing is a plain old fashioned "burning" pattern. This would be my best hunch. Elimination could be to lower the current density as the concentration of the nickel in the solution decreases.(Not attractive if you are under time constraints for plate out).

Remember too, that nickel is one of the magnetic metals, although not as magnetic as steel. You may wish to contact your supplier and see if they have a nickel additive that may help as an antiburn agent, to minimize the burning. Sincerely,

ed budman eb sig
Ed Budman [dec]
- Pennsylvania
With deep sadness we advise that our good friend Ed passed away Nov. 24, 2018

Thanks Ed I will check it out. Alfonso

Alfonso Benavides
- Corpus Christi, Texas

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