Abstract: Incorporating an additive into a tin electroplating bath substantially inhibits soluble ferrous ions, ferric ions, and stannous ions from reacting thus minimizing the formation of stannic tin which is lost in the plating sludge.

Abstract: The present invention relates to a method of completely recovering nickel and zinc metal from multiple plating process waste streams by first separating the waste streams into a clean, relatively constant flow and/or concentration fraction and a dirty, variable flow and/or concentration fraction. Metal is recovered from the clean fraction by ion-exchange so as to concentrate the extracted metals for direct return to the plating bath. The effluent from the ion-exchange step is then blended with the dirty, variable flow and concentration fraction. This blended flow is first neutralized and then precipitated in a two-stage process using a sodium hydroxide solution. The resultant slurry containing the metal precipitate is filtered to yield a filter cake containing recovered nickel and zinc. This filter cake can then be further processed to recover the metal for reintroduction into the plating bath or for other uses.

Abstract: The invention relates to an improvement in a process for electrodepositing a protective coating of zinc or a zinc alloy on steel or other metal substrates in which the process utilizes a metal conductor roll or conductor roll with metal sleeves and contains a rinsing bath with a mineral acid solution associated with the roll, the improvement comprises providing at least 50 ppm of hydrogen peroxide or a peroxydisulfate compound in the mineral acid bath.

Abstract: This invention is directed to a method of treating a selectively galvanized steel strip, such as one-side electrogalvanized sheet, to improve the appearance and paintability of the non-galvanized areas of said strip. The post chemical processing of the strip, which processing does not chemically attack the zink-coated areas of the strip, comprises the steps of applying to the strip a solution of an aqueous bifluoride salt, followed thereby by rinsing said strip with a dilute caustic solution.

Abstract: 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.

Abstract: 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.