Co-carbonization behavior of the blended heavy oil and low temperature coal tar for the preparation of needle coke

Abstract Needle coke is mainly used in high-power electrode material for electric arc furnace, the economy of material cost and the quality of co-carbonized products are widely concerned. Low temperature coal tar (LCT) and heavy oil (HO) were used to prepare needle coke by liquid phase carbonization, and the co-carbonization behavior as well as structural evolution of blended materials were also studied. It was concluded that the derived needle coke pyrolyzed from the blended HO and LCT showed obvious structural separation interfaces between the anisotropic acicular structure and isotropic matrix. The abundant primary quinoline insolubles (QI) in LCT prevented the penetration of smaller molecules. The removal of primary QI in LCT improved the compatibility of HO and LCT-derived structure and eliminated the obvious structural separation interfaces. The furfural extraction significantly regulates the molecular composition distribution which is conductive to promote interactions within compositions and improve the order of structural evolution. The sample extracted at 60℃ after removing QI (LCTE60) contained 25.7 wt% of alkanes and naphthenes, and the total content of bicyclic aromatics, tricyclic aromatics and tetracyclic aromatics occupied 45.3 wt%. The derived needle coke prepared from blended HO and LCTE60 with the proportion of 50:50 obtained the needle domain content of 60 wt% and the optical texture index (OTI) of 71.66. This study provides theoretical basis for the co-carbonization of needle coke production.