Bethlehem Steel Corporation

Stewart E Rauch, Jr

Richard N Steinbicker

Thomas W Fisher

An improved acid halogen electrotinning bath composition for depositing a smooth, coherent layer of tin onto a steel substrate contains about 0.10 to 4.0 grams per liter of solution of at least one oxidation inhibiting agent comprising an organic ring compound which has a radical group such as --NH.sub.2 or --NO.sub.2 in the ortho or para position, for example para-aminoacetanilide and para-nitroacetanilide. Organic ring compounds, para-aminophenylacetic acid and 4-aminoantipyrine may also be added to the bath together with sodium ferrocyanide to inhibit the oxidation of the bivalent tin ions.

Acid electrotinning bath

A process for the extraction and recovery of hydrated stannic oxide and alkali metal ferrocyanide from the sludge formed in a halogen tin electrodeposition bath is described. The process comprises dissolving the ferrocyanide compounds and the tetravalent tin compounds present in the sludge in an alkaline medium, removing any insoluble materials, precipitating hydrated stannic oxide from the solution by neutralization of the solution, and separating the hydrated stannic oxide from the solution which then contains ferrocyanide ion together with acid and base counterions.

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Bethlehem, PA, United States of America

Stewart E Rauch, Jr