| Needle coke is a high-quality carbon materials developping in the 1970s, and it is mainly made of graphite electrodes used in electric arc furnace steel making, aluminum smelting and so on. Raw materials are coal tar and petroleum asphalt. Coal tar pitch as raw material to prepare high-quality needle coke is important significance to make full use of our abundant resources of coal pitch, produce high value-added products, reduce dependence on foreign products.The purpose of this research was to manufacture needle coke by solvent. It was that firstly to remove the quinoline-insolubles(QI) of coal tar pitch by mixed solvent-centrifugal method, and to obtain the refined pitch of QI<0.1%. It has been carried out to investigate the effects of solvent ratio, centrifugal time and more kinds of operating conditions on the QI content and refined pitch yield. Then, the coke was prepared by thermal polymerization of refined pitch under certain conditions. The influences of different raw materials, thermal polymerization temperature, time, pressure and other factors on coke structure, performance were investigated. Finally, the coke was calcined to obtain calcined coke, the elemental composition,morphology and performance of the coke and calcined coke were analyzed. The results showed that:(1) In the QI centrifugation process, for the medium temperature pitch, when the ratio of aromatic hydrocarbon to the alkanes was 0.6, the QI content of refined pitch was lowest, for the soft pitch, when the ratio of aromatic hydrocarbon to the alkanes was 0.4, the QI content of refined pitch was lowest; when the solvent ratio was constant, the yield of refined pitch increased with the increase of the ratio of aromatic hydrocarbon to the alkanes; when the ratio of aromatic hydrocarbon to the alkanes was certain, the QI content and yield of refined pitch decreased with the increase of the solvent ratio; when centrifugal time was longer, the QI content and yield of refined pitch is lower. centrifugal centrifugal time longer refined asphalt from the lower QI, the lower the yield; raising the centrifugal temperature was helpful to QI separation. Suitable operating conditions were:solvent ratio≥1.0, rotation speed in 2000rpm, centrifugation temperature of 80℃and centrifugation time of 16min, can obtain the refined pitch of QI≤0.05%.(2) In the thermal polymerization process, the QI content of raw material influenced the coke structure greatly, the high QI content hindered the development of mesophase ordering, easy to generate mosaic structure. Thermal polymerization temperature was too low to form a mesophase ordering; temperature was too high, the coke prepared often poor and loosely ordered. Thermal polymerization time was conducive to the full formation of mesophase, financial and ultimately the formation of non-spherical mesophase streamlined, fibrous coke structure. Heating rate was too fast on formation of sheet structure and semi-coke mosaic structure. Pressure was too low, the random arrangement of the mesophase was formed; too high, it was easy to form the porous structure of coke, and mosaic. Stirring at the initial reaction stage contributed to balance the composition, temperature, and to form needle structure. Flow-raggio was conducive to the formation of ordered coke, but relief should be slow. The most appropriate conditions were:heating rate of 2℃·min-1, thermal polymerization temperature of 460℃, pressure 0.35MPa, thermal polymerization 20h, prepared coke with the best ordered fiber structure.(3) Calcining process can greatly reduce the heteroatom of coke, can remove light components. Calcining can improve the crystal structure, so that the stacking height of molecules was increased, molecular layer arrangement was tend to compact. The lattice parameters of calcined coke and foreign needle coke were similar, true density and ash content reached the new Japanese cosmetic company standards.
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