METHOD FOR PROTECTING METALLURGICAL GRAPHITISED ELECTRODES AGAINST HIGH-TEMPERATURE OXIDATION Russian patent published in 2022 - IPC C25B11/04 H05B7/06 

FIELD: metallurgy.

SUBSTANCE: invention relates to electrometallurgy, in particular, to production of high-temperature oxidation-resistant electrodes from synthetic graphite, applied in electrolysers for producing magnesium and in other metallurgical units. In the method for protecting metallurgical graphitised electrodes against high-temperature oxidation, an impregnating composition is first prepared, containing, wt.%: aluminium dihydrophosphate 7 to 10; zinc dihydrophosphate 25 to 30; orthophosphoric acid 12 to 16; a wetting agent - isopropyl alcohol 2; water the rest. Prior to impregnating, the graphitised electrodes are first cleaned from mechanical dust, then held under evacuation at a pressure from 700 to 1,000 Pa for 1 to 2 hours. The previously prepared impregnating composition is then poured into the impregnation chamber, avoiding air ingress, then heated to a temperature of 40 to 45°C, and the electrodes are held in said composition as calculated for 2 to 2.5 hours per 50 mm of the cross section of the electrode from edge to the centre thereof. After holding, the electrodes are directed for weight control: if the weight gain is below 7%, they are directed for re-impregnation; if the weight gain is below 7%, they are directed for drying. The electrodes are dried in two stages in a drying furnace: at the first stage, heated at a rate of 2 to 3°C/min to a temperature of 140 to 150°C and held for 1 to 1.5 hours; at the second stage, at a rate of 10 to 15°C/min to a temperature of 550 to 600°C. Then the electrodes are left to cool, wherein a crystalline film is formed on the accessible surface of the electrode.

EFFECT: increase in the high-temperature oxidation resistance of graphitised electrodes, prolongation of the operating life of graphitised electrodes.

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