SU43876A1 - The method of processing graphite anodes for the electrolysis of alkali metal chloride salts - Google Patents

Description

The proposed method of processing graphite anodes for the electrolysis of alkali metal chloride salts used in the electrical production of chlorine is used to increase the service life of graphite anodes.

As is known, the essence of the usual chemical treatment of graphite electrodes, when using linseed oil, followed by chlorination in a cold and hot aqueous medium, is reduced to the following processes. The saturated organic acids present (palmetinic, stearic, myristic, orrahinov), have a low melting point and specific gravity, are incapable of chlorine and oxygen addition reactions when chlorinated in hot water solution. These flax oil acids release the pores of the electrodes. Unsaturated acids, which are part of linseed oil (oleic, linoleic and linolenic), have the ability to add chlorine and easily oxidize at the place of double bonds, form chloroxy acids and resin-forming substances, which have a very significant melting point and a high specific volume, which allows to strongly envelop the pores of the electrodes, reducing significantly the cross section of the capillaries,

the most obstacle to the penetration of electrolyte into the pores of the electrode during polarization of the latter. Thus, in the pores of the electrode, no conditions are created for the discharge of ions leading to the oxidation of graphite and, consequently, to the destruction of the electrodes.

The proposed method differs from the existing ones in that it can be intensified with the help of the strongest oxidant of the electric current.

The drawing shows a vertical section of a bath for carrying out the method of processing graphite anodes for the electrolysis of alkali metal chloride salts.

Electrodes soaked in flax oil for 15 to 18 hours at a temperature of 85-95 are removed from the latter and kept for 2-3 days in air. The electrodes dried in this way can already go for electrochemical processing.

After collecting the anode packet from electrodes impregnated in linseed oil, it is loaded into a bath that works with external anolyte saturation, in which the electrodes, having worked for 12 hours with cold brine (25 - 40 °) and 24 hours with hot brine (65 - 85 °) with a current of 200-250 amperes, removed from the bath and already chemically treated go into operation.