GB899028A - Improvements in or relating to the electrolytic manufacture of iron - Google Patents

Abstract

899,028. Depositing iron electrolytically. MONTAN - UNION HANDELSGESELLSCHAFT. March 3, 1961 [March 3, 1960], No. 7942/61. Class 41. A continuous process for depositing iron from an electrolyte containing it, electrolytically, uses as cathode an endless moving strip upon which a firmly adherent thin layer of iron is deposited. The iron-poor electrolyte is withdrawn and replenished with Fe<11> ions, by adding FeSO4 from iron pickle solution or by dissolving iron scrap therein, preferably with addition of acid, and removing undesired metals before returning the re-charged electrolyte to the main cell. The re-charging is effected in a battery of vessels, to provide a continuous supply of new electrolyte. A matrix of copper strip 1, covered with a separating layer, e.g. of a heavy metal oxide or sulphide, passes through a preliminary electrolytic cell A in a vertical position where a thin coating of iron is deposited at low current density, and is smoothed by steatite elements 4 before entering the main electrolytic cell B. Anodes 3 are mounted close to the strip providing high current density at lower pH values. The coated matrix is then neutralized by washing with alkali in a spray bath 5 and is washed in a spray bath 6. At 7 the iron powder is removed from the strip by high-frequency vibration, hot inert gas, infra-red or electric induction heating of the strip, which is finally coated with a corrosion inhibitor, e.g. dicyclohexylamine nitrite, and re-coated in an inert atmosphere with the separating layer. The iron electrolyte is introduced into the cell B preferably vertically to flow across the face of the vertical strip, and the anodes of graphite or magnetite have convex faces to prevent heavier deposit of iron at the edges of the strip. Iron-depleted electrolyte is fed through a pipe 19 into one of the battery of dissolution vessels 9, where the electrolyte is circulated through a pipe from the bottom to the top of the vessel charged with scrap, and having a porous false bottom through which HCl or H2S is forced to form fine streams into the electrolyte. The vessel may be heated or cooled. The enriched electrolyte is led to a reactor 13 where nickel and copper are partly removed by precipitation on iron powder added in the reactor. The partially purified electrolyte then passes to an intermediate electrolytic cell 14 where traces of Ni and Cu are removed by deposition. Final treatment with reagents, e.g. sodium fluoride, in a vessel 15 removes Cr, Zn, Mn, Al and Sn and some ferric iron as an insoluble complex, which is separated in a filter 16 together with carbon, sulphur, and other solid impurities. Instead of iron scrap, pickle solution may be used after reducing ferric salts with H2S, and a solvent added whereby the ferrous sulphate is precipitated, which is separated and re-dissolved in water and admitted to the dissolution vessel 9.