| 摘要 |
PURPOSE:To produce needle coke suited for use in an artificial graphite electrode, exhibiting less buffing in a step of graphitization and having a low coefficient of thermal expansion, by successively conducting oxidation and hydrogenation of needle-form raw coke under particular conditions. CONSTITUTION:Needle-form raw coke is heated and oxidized at 350-700 deg.C in an oxidizing atmosphere (e.g., air). Subsequently, the coke is heated to 500-1,000 deg.C in a hydrogen atmosphere optionally contg. steam, followed by either temporary cooling to 200 deg.C or below or hydrogen treatment. Then, the coke is baked at an ordinary baking temp., thereby preparing the desired needle coke. As a result, since the heat treatment is performed at a relatively low temp. before desulfurization in a hydrogen atmosphere and relatively low temp. is employed as a heating initiation temp. in a hydrogen atmosphere, the desulfurization ratio improves and the buffing of baked code is reduced, with the thermal expansion coefficient lowered. |
