Gas chromatographic study for the evaluation of the suitability of bituminous waste material as an additive for coke production

Waste materials derived from coking plants can be used in situ as bituminous additives in cokemaking. The effectiveness of such materials in the plastic coal range was compared with a coal-tar and four derived pitches of different applications. The volatile matter released from 400 up to 500 degrees C by the additives (VM400-500), which was evaluated by thermogravimetric analysis, was clearly related to the extent of the modification of the Gieseler maximum fluidity of coking coal/additive blends. The decrease in the amount of volatile fraction in the CS, extracts of the additives and the increase in the abundance of polycyclic aromatic hydrocarbons (PAHs) of relatively high molecular mass were evaluated by capillary gas chromatography with flame ionization detection (GC-FID) analysis. From regression analysis, it can be deduced that there is a relationship between the compositional parameters deduced from GC-FID analysis and the volatile matter released in the plastic range of a coking coal (VM400-500). Both composition and VM400-500 of the additive, were found to be responsible for the enhancement in fluidity caused by the presence of the additive in the co-carbonization system. GC-FID analysis may be a good method to assess the effectiveness of a bituminous additive in the coal plastic stage and to acquire a better understanding of the components involved in this critical stage of the carbonization process. The changes induced in the plastic range by the additive modify the development of coke anisotropy and the bonding between coke matrix and inert material and, consequently, are responsible for the improvement in the coke properties. (C) 1998 Elsevier Science B.V. All rights reserved.