GB1304527A - - Google Patents

Abstract

1304527 Electrolytically recovering Ni, Co and/or Fe LANCY LABORATORIES Ltd 30 Oct 1970 [25 Nov 1969] 57509/69 Heading C7B In recovering Ni, Co and/or Fe values from a metal treatment solution adhering to treated articles, the treated articles are immersed in or otherwise contacted with recovery solution at a wash station, the recovery solution is passed to an electro-deposition station where the metal values are electro-deposited, and at least part of the recovery solution is then recirculated to the wash station. The metal may be recovered as a coherent film or as a powder. The treatment to which the article has been subjected may be electro- or chemical plating, pickling, etching, electro- or chemical polishing, electro-chemical machining, chemical milling or stripping. The metal treatment solutions, in addition to containing Ni, Co and/or Fe, may contain Cu, Sn, Cr Zn and/or Pb. The term "article" includes an article-carrying rack or barrel. As shown, articles are treated with a metal treatment solution at 11, contacted with a recovery solution at 12, and water rinsed at 13. Co, Ni and/or Fe values are electrolytically recovered from the recovery solution in a cell 15 and the solution is then recirculated by a pump 16. The cell 15 has a carbon anode 17, rotating cathodes 18 and a heating coil 19. Compounds which increase the efficiency of the electro-deposition are added from a tank 20. In modifications and alternatives:- There may be a plurality of recovery cells 15 which may be connected in series or parallel with regard to solution flow. During recirculation, the recovery solution may be purified by filtration through activated carbon, by ion exchange or by electrodialysis. The recovery solution may be stirred or agitated by blowing air therethrough adjacent to the cathodes. Sonic or ultrasonic waves may be applied to the cathodes or solution. The cathodes on which the metal values are electro-deposited may be in the form of fluidized finely divided metal powder or small particles of inert material which have been coated with a conductive metal. The conditions in the recovery cells may be adjusted in such a way that one or more metals are electro-deposited preferentially to one or more other metals, e.g. the current density may be held lower in one container than in the other in order to preferentially deposit Zn, Fe, Cu and/or Pb which may have been added to the treatment solution or been present as impurities. The following may be added to the recovery solution (i) compounds which increase the electrical conductivity, achieve the optimum pH or buffer the solution, e.g. acids, alkalis or salts such as those formed by reacting alkali or alkaline earth metal or NH 3 , Al, Mn, Mg with HCl, H 2 SO 4 , HNO 3 , HF, NH 2 SO 3 H, HBF 4 , H 2 SiF 6 or an organic acid, (ii) compounds which complex the metal in solution where a number of metals are present to lessen preferential deposition of one or more thereof, e.g. gluconic, tartaric or citric acid or their salts, (iii) compounds which affect the crystal size or the physical or mechanical properties of the electro-deposited metal, e.g. benzene sulphonate, naphthalene sulphonate, glue or gum arabic, (iv) compounds (unspecified) which increase or decrease surface tension and (v) compounds (unspecified) which precipitate metallic impurities or sulphates or fluorides.