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Treating effluent tin from anodizing electrocoloring tank

We operate an architectural anodizing line which includes a stannous-sulphate AC electro-coloring tank, followed of course by rinsing. Dragout from the tin colouring tank (containing typically 11g/L stannous and 24g/L sulphuric acid) produces stannous ions at the effluent treatment plant where simple neutralization precipitates aluminium hydroxide which is contaminated with tin in the ppm range.

Does anyone have any idea whether we could remove the tin from the rinse after the electrocolouring tank, by electrodeposition? (I presume the tin leve lwould be 1g/L or less, and quite acidic; I am having some analyses done)

John Leitch
- Pietermaritzburg, South Africa

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