Processing and utilization of coal tar pitch

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1. QI-free asphalt – Primary use: asphalt specifically designed for impregnating graphite electrodes； Production method: It is obtained by using medium-temperature asphalt or soft asphalt as raw material, removing quinoline insolubles (QI), and then carrying out modification (primarily to increase TI and coking value). The main methods for removing QI include solvent sedimentation, centrifugation, filtration, etc.; to date, only solvent sedimentation has been used in actual industrial production. Taiwan’s China Steel uses the by-product asphalt produced from carbon microspheres (negative electrode materials for lithium-ion batteries) as raw material to produce QI-free asphalt, but its quality is inferior to that produced by the solvent sedimentation method. The main parameters of QI-free asphalt as an impregnant are: QI less than 0.5%, TI (toluene-insoluble matter) greater than 18%, softening point of 85°C–90°C, and coking value greater than 49%. Regarding domestic R&D efforts, in 2000, Yankuang Kelan Coal Coking Co., Ltd. was the first to achieve industrial production based on the solvent-based pretreatment method for needle coke. At present, the Shandong Jining Carbon Group is in production.