Addition Effect of Aromatic Amines on Coal Fluidity and Coke Strength

Abstract

BackgroundToday, high-strength coke is actively pursued to operate blast furnace with low reducing agent. 1) Caking properties are the important parameters in coal blending techniques to produce high-strength coke. 2) In particular, Gieseler plastometer method standardized by JIS M8801 have long been used for measuring 'fluidity' as caking properties. On the other hand, recently, the amount of high-quality coal with high fluidity has been limited. The tight supply and rising price of high-quality coal with high fluidity is an inevitable problem in Japan, therefore development of technique to utilize slightly and non-caking coals is required. To cope with this problem, caking additive method which improves fluidity of coal has been developed and commercialized. 3-7) It is known that caking additives improve coal fluidity, promote liquid-phase carbonization, increase anisotropic texture in coke. However, mechanism of caking additives for improving coal fluidity is still unclear. It is important to search for more effective chemical substances to clarify the mechanism of caking additives to improve fluidity of coal.In order to clarify effective chemical substances to improve coal fluidity, there are a number of studies on 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. KEY WORDS: cokemaking; coal thermoplasticity; caking additive; aromatic amine; slightly caking coal.the interactions between coal and chemical substances. 8-10) Koyano et al. 9) investigated influences of polycyclic aromatics on coal fluidity. They reported that polycyclic aromatics with higher molecular weight and higher boiling point had superior effect on coal fluidity and coke strength. Tsubouchi et al. 10) investigated the e...

Effects of Hydrocarbon Addition on Increase in Dilatation of Coal

“…20) In the previous study, changes in the fluidity of coal were investigated when several hydrocarbon reagents were used. For example, polycyclic aromatic hydrocarbons, 21) aromatic hydrocarbons containing nitrogen, [21][22][23][24] and aromatic hydrocarbons containing oxygen. 21,25) These investigations revealed that the fluidity of coal increased when a PAH with a high boiling point or an aromatic hydrocarbon containing nitrogen was used, but decreased when an aromatic hydrocarbon containing oxygen was used.…”