GB803844A - Improvements in or relating to the electrolytic production of iron powder - Google Patents

Abstract

803,844. Producing iron powder electrolytically. SOC. D'ELECTRO-CHIMIE, D'ELECTRO-METALLURGIE ET DES ACIERIES ELECTRIQUES D'UGINE. Jan. 25, 1957 [Feb. 8, 1956], No. 2857/57. Class 41. A process for producing iron powder comprises electrolysing an oxygen-free dilute aqueous solution of a ferrous salt, e.g. the chloride or sulphate, in the absence of oxygen under such conditions that pulverulent detachable iron is formed on the cathode, periodically detaching the iron powder which is deposited on the cathode, and removing the powder from the electrolyte out of contact with oxygen. Oxygen is eliminated from the apparatus in which the process is carried out by employing a closed apparatus from which the air has been expelled and replaced by an oxygen-free gas, or by employing an open apparatus with an airimpermeable liquid layer, e.g. petrol, on the electrolyte. An inert gas, e.g. argon or helium, may be bubbled through the electrolyte. The concentration of the ferrous salt is 0.05 to 0.5 mol. per litre and a small amount of ferric salt, not more than 1: 100 of the amount of ferrous salt, may be included in the electrolyte. The pH is between 3 and 5, the cathode current density between 0.5 and 5 amps. per sq. cm. and the electrolyte at room temperature or below, e.g. 15 ‹ C. to 25‹ C. An iron or graphite cathode may be employed, or one of a metal electronegative with respect to iron, e.g. copper, and the anode, which may be coaxial with and may surround the cathode, may be graphite or platinum, a diaphragm separating the electrodes, or a soluble iron anode may be employed and no diaphragm. The cathode, which may be movable, may be subjected periodically, e.g. every 1 to 2.5 seconds, to shocks by mechanical or electromagnetic means, or to intermittent brushing or scratching to remove the powder deposit. In one example, a copper wire cathode 1.1 mm. in diameter was connected to the moving part of an electromagnet which drew the wire periodically into a close-fitting glass sheath. The detached powder may remain in suspension or sink to the floor of the apparatus, where it may be retained by a magnetic field, for subsequent filtering or decanting and washing in water and acetone. Anode current densities of 0.005 to 0.04 amp. per sq. cm. are mentioned.