GB189919785A - Electro-chemical Process for Cleaning Metal Surfaces. - Google Patents

Abstract

19,785. Vereinigte Elektricitõts- Actiengesellschaft and Klaudy, J. Oct. 3. Cleaning; pickling.-A metal surface is electrolytically cleaned by first suspending it as a cathode in a salt solution to remove grease, and afterwards using it as an anode or cathode-according to the metal under treatment-in an electrolytic cell containing an electrolyte which can be regenerated. When treating iron, copper, copper alloys, and similar metals, they are arranged as anodes, and the electrolyte is one which will attack the metal, and form a soluble hydrate on the cathode. This hydrate will then combine with the acid of the metallic salt formed, precipitating the metallic hydrate, and re-forming the original electrolyte. For iron, sodium sulphate is the electrolyte employed. Zinc, aluminium, and like metals are treated when connected as cathodes, unattackable anodes being employed. In this case also, an insoluble hydrate of the metal is precipitated, by means of a secondary reaction between the soluble compound formed at the cathode, such as zincate or aluminate, and the acid set free at the anode. The electrolyte is withdrawn, either continuously or intermittently, is fined and filtered, and is then returned to the cell.