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Shaanxi Coal Group makes new progress in producing high-end carbon materials (acicular coke) from medium- and low-temperature coal tar. Author/Source: Collaborative Group on Advanced Processing and Hydrogenation of Coal Tar. Date: 2021-04-20. Clicks: 7. Since 2018, Shenmu Tianyuan Chemical Co., Ltd. under Shaanxi Coal and Chemical Industry Group (hereinafter referred to as Tianyuan Company) has been working on the research and development of high-end carbon materials for the domestic market. After three years of continuous exploration and experimentation, it has now made breakthrough advances in the field of producing high-end carbon materials (acicular coke) from medium- and low-temperature coal tar. Facing the new opportunities arising from the supply and demand dynamics in the carbon products market, high-end products such as ultra-high power and high power graphite electrodes, as well as anode materials for electric vehicles, are experiencing rapid growth and a situation where demand exceeds supply. Taking the situation into account, Tianyuan Company made full use of the properties of medium- and low-temperature coal tar to produce value-added products such as needle coke or other carbon materials. By doing so, it established a strategy for continuously expanding the industrial chain for the deep processing of coal tar, thereby paving the way for the company’s transformation from producing only basic coal tar derivatives to offering differentiated, high-end products with higher added value. At the end of 2017, the technical staff of Tianyuan Company made several trips to Shanghai, Liaoning, Shanxi, Shandong and other places to conduct in-depth research on the market for producing high-end carbon materials (acicular coke) from medium- and low-temperature coal tar. Research shows that the domestic enterprises producing needle coke are represented by Shanxi Hongte Coal Chemical Co., Ltd. Its coal-based needle coke boasts a high true density and high electrical conductivity, which give it advantages over petroleum-based needle coke, resulting in significant market and economic benefits. Currently, the production capacity of medium- and low-temperature coal tar in Yulin is around 10 million tons per year, but there are no projects in China that utilize medium- and low-temperature coal tar as raw material to produce needle coke. The reason for this is that medium- and low-temperature coal tar contains relatively low amounts of aromatics, has a wide molecular distribution range, and features low levels of tricyclic and tetracyclic aromatics; as a result, it is extremely difficult to develop process technologies for producing needle coke, a carbon material, using medium- and low-temperature coal tar as raw material. Acting in line with the circumstances and adapting to them, Tianyuan Company has, since 2018, explored through analysis and testing the feasibility of using medium- and low-temperature coal tar as a raw material for coal-based needle coke. By comparing the existing coal-based needle coke production processes that have been put into industrial use, and taking advantage of the company’s current advanced deep-processing technologies for medium-temperature coal tar, a technological innovation strategy for producing needle coke from medium- and low-temperature coal tar has been gradually developed – a strategy that features advanced technology, reliable operation, stable product quality, and suitability for the company’s actual production conditions. In the realm of technological innovation, Tianyuan Company did not opt for the conventional approach; instead, it took a long-term perspective and chose to pursue a path of breakthroughs from scratch. This technology was developed in 2019; using medium- and low-temperature coal tar pitch as raw material, and by making full use of theories on colloid formation and the kinetics of pitch carbonization, it opened up an innovative path for producing high-quality needle coke and anode materials from medium- and low-temperature coal tar. The first moves have already been made; a clear plan for progress is in place. The pilot and pilot-scale production of high-end carbon materials (acicular coke) from medium- and low-temperature coal tar is advancing steadily. Taking into account the special properties of medium- and low-temperature coal tar, the technical staff at Tianyuan Company pooled their creativity and came up with numerous innovative solutions. By optimizing the raw material pretreatment process, they produced high-quality needle coke feedstock in the form of refined asphalt, which has an acceptable level of quinoline insolubles and a reasonable molecular structure. The quinoline insoluble content in this refined asphalt used as coking feedstock is well below the specified value (<0.1%). Meanwhile, using delayed coking pilot and pilot-scale plants, the process conditions for the production of needle coke were optimized based on the preparation of refined asphalt ； By examining the effects of process parameters such as coking temperature, coking time, heating rate, and coking pressure on the microstructure of the green coke, needle-shaped coke with good overall density and a silver-gray metallic luster to its surface was ultimately obtained. In 2020, impurities in the raw material were removed through mixed-solvent extraction, resulting in qualified needle coke feedstock (refined pitch) whose specifications exceeded the design values. In 2021, the process conditions for producing needle coke were determined based on the preparation of refined asphalt. The mechanisms of colloid formation and destruction in coal tar asphalt within solvents, as well as the coking conditions for refined asphalt, were explored. Through pilot tests in the technology research and development center and scale-up tests using production facilities, factors such as temperature, pressure, and heating rate were addressed, resulting in a coke product with a silver-gray metallic luster. Through analysis using a polarizing microscope and a scanning electron microscope, it was found that the product has a microstructure characterized by good anisotropy and a wide-ranging, streamline-like porous pattern. This product exhibits properties such as a low coefficient of thermal expansion, high electrical conductivity, and easy graphitization; its quality far exceeds expectations, making it fully suitable as a raw material for the production of high-power and ultra-high-power graphite electrodes. It filled the gap in domestic technology for the production of needle coke from medium- and low-temperature coal tar. These fundamental research results provided the design basis data for Tianyuan Company’s “pre-treatment device capacity expansion and upgrading project”. To date, 5 invention patents and 1 utility model patent have been applied for using this technology.