The carbonization of a non-hydrogenated extract (STC) from a low-rank coal (C, 83 wt%) of high fluidity was studied as single carbonizations and as co-carbonizations with additives, an objective being the production of needle-coke. The coke from STC had an optical texture of fine-grained mozaics; however, fractionation followed by co-carbonizations were effective in modifying carbonization properties. The lighter fraction of STC could give a coke with flow texture but in reduced yield. The addition of hydrogenated Ashland A240 pitch (HA240) in a quantity as low as 20% could effectively modify the carbonization properties of STC. A novel co-carbonization, in which an additive such as dihydroanthracene is recovered at the latter stage of the carbonization in the dehydrogenated form, was found to be effective also, although a relatively large amount of the additive was required. Among the non-hydrogenated additives, Ashland A240 pitch was the most effective in modifying the STC. The cocarbonization of fractionated STC reduced the quantity of additive required while maintaining a reasonable coke yield. Some practical aspects for the production of needle-coke from STC are discussed.
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