Article ID: ISIJINT-2018-815
Coal fluidity is an important parameter in coal blending techniques for coke making because it strongly influences coke qualities. On the other hand, recently, the amount of high fluidity coal has been limited. To cope with this problem, caking additive method which improves fluidity of coal has been developed and commercialized. However, since tight supply of high fluidity coal is anticipated in the future, it is of great importance to develop more effective caking additive. Therefore, in this study, we investigated effect of 11 kinds of polyaromatic hydrocarbons which include oxygen, sulfur and nitrogen containing compounds on coal fluidity in order to search for more effective chemical substances. The additives were added to low fluidity coal, and fluidity analyses were carried out according to the Gieseler plastometer method. Addition of sulfur and oxygen containing compounds lowered fluidity of coal, whereas addition of aromatic amines enhanced fluidity of coal. Coal fluidity ameliorated with increasing the molecular weight of aromatic amine, and N,N'-di-2-naphthyl-1,4-phenylenediamine (DNPD) was the most effective aromatic amine in this study. Carbonization tests in an electric furnace were conducted to investigate an effect of DNPD on coke strength. As a result of adding only 1 wt% DNPD, fluidity of blended coal and coke strength (Drum Index) were highly improved.