PURPOSE: To easily obtain isotropic graphite material having high purity and a low anisotropy ratio by finely crushing amorphous pitch coke, bringing into contact with an aq. strong acid soln. for a fixed time period to remove ash, thereafter washing, drying, molding, sintering and graphitizing.
CONSTITUTION: The amorphous pitch coke produced by carbonizing coal tar pitch, is crushed to ≤250μm. Then, the crushed pitch coke is brought into contact with the aq. strong acid soln. (e.g., aq. hydrochloric acid soln.) for ≥5min to remove metallic impurities contained in the coke. The coke powder obtd. after washing and drying, as raw material, is molded with or without pitch as binder, sintered and graphitized to obtain the isotropic graphite material having high purity and ≤1.05 anisotropy ratio. Thereby, the load for highly purifying when the coke powder is graphitized, can be lightened, because the metallic impurities in the amorphous pitch coke as raw material, have been removed in advance.
MUKAI KOICHIRO
FUJIMOTO KENICHIRO
ORITA MASAFUMI
NIPPON STEEL CHEMICAL CO