Production of High Purity Artificial Graphite

The most effective treatment to remove V from raw coke was to treat the coke with 5% of NH4Cl and heat at 2000 deg C for 3 hr. A graphitization furnace was used to attain the temperature of 2000 deg C. Satisfactory results were also obtained by the same purification and graphitization process by adding the necessary amount of NH4Cl or NaCl to the raw mixture. For molded graphite products, impregnation with saturated soiutions ofNH4Cl or NaCl and treatment with Cl2 during heating were tried. The methods were also applicable to the purification of graphite of low purity. The degree of graphitization of purified graphite was slightiy higher than that of unpurified graphite. The elimination of B from graphite must be attained in order for it to meet the requirement for use in atomic reactors. It was shown that the treatment of graphite with Cl2 containing HF mist at 2000 deg C for 3 hr is effective for the purpose of decreasing B content to less than 1 ppm. The formation of (CF)n must be avoided by use of the Cl2-HF mixture at high temperature, because (CF)n is formed below 700 deg C. (H.H.D.)