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Recovering Nickel from spent Nickel plating solution

Hi Forum members,
I have some spent (end of life) all-chloride Nickel bath and want to recover the nickel on steel plates which act as cathode during the electroplating. The test was carried out for a day and had reasonably heavy deposit on the part. When continued it for another day I experienced different result where greenish and dark deposit were found especially on high current area. Nickel chips were removed from the anode cage before conducting the process. I thought most of the nickel were deposited ready and the solution's NiCl concentration has gone down too low which caused the above condition. Analysis shows the concentration is still high, 200 g/l of NiCl and wondering how to get maximum nickel out of the solution. May I know the reason or science behind it?

S.Guna Subramaniam
Plating and TS - Shah Alam, Malaysia
February 25, 2011

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Electrolytic recovery of nickel is more difficult than for most other metals. It usually requires heat, pH control,agitation, and a buffer like boric acid.

One of the problems is the formation of hydroxides at the cathode surface that can precipitate nickel hydroxide. This is the reason for the buffer, and good agitation. If the pH is not continuously controlled, it will drop and as a consequence of this, the nickel plating efficiency will decrease and the formation of hydroxides at the cathode surface will increase.

Lyle Kirman

Lyle Kirman
consultant - Cleveland Heights, Ohio
February 28, 2011