Depending on the raw material source, needle coke is categorized into oil-based and coal-based, with somewhat different production methods. Oil-based needle coke was first successfully developed by Great Lakes Carbon Company in the United States in 1950. In 1964, Union Carbide Corporation used needle coke to produce ultra-high power electrodes.
Currently, the majority of global needle coke production is produced by Continental Petroleum Company in the United States. Japan's Mizushima Plant has also successfully produced needle coke using oil-based feedstock. However, the vast majority of needle coke is produced from low-sulfur heavy petroleum oil from specific origins, significantly limiting its availability. To expand raw material sources, countries such as Japan and Germany have researched producing needle coke using coal tar pitch as a raw material.
The key to needle coke production is raw material conditioning, primarily to remove native quinoline insolubles that hinder the growth of mesophase spherules. Coal-based needle coke raw material conditioning is more challenging than oil-based needle coke because coal tar pitch contains a higher native content and a more complex composition.
It contains not only amorphous carbon formed by the thermal polymerization of certain aromatic polymers during coal tar distillation, but also coal dust and coke fines carried with the coal gas from the carbonization chamber of the coke oven. These adhere to the mesophase, hindering the growth and fusion of spherical crystals. Consequently, after coking, it is impossible to obtain a well-structured needle coke structure. Therefore, the raw materials that hinder the growth of spherical crystals must first be removed, and then the composition must be adjusted to obtain the raw materials required for needle coke production.