Consumption of graphite anodes in chlorine manufacture by brine electrolysis

The anodic behaviour of carbon and graphite electrodes in aqueous electrolytes is described and the important reactions leading to the consumption of graphite during chlorine manufacture by brine electrolysis are discussed in detail. The present state of knowledge concerning the effects of chlorine cell electrolysis conditions on graphite consumption is also reviewed. A new investigation of the influence of graphite manufacturing variables and properties on consumption is also described. The variables studied were coke particle size, degree of pitch impregnation and the final heat treatment at the graphitization stage. Properties considered included electrical resistivity, apparent density, average crystallite size and unpaired electron spin density. The resistance of the graphite to anodic oxidation was found to increase with increasing coke particle size, increasing pitch impregnation and increasing final heat treatment temperature (up to 3000°C). Unpaired electron spin density was the property found best to correlate with this resistance.