2014 Volume 100 Issue 2 Pages 127-133
Steel industries need to increase the use of low-grade coals in coke making due to the recent rapid increase in coking coal price. To do so, it is necessary to effectively use binders, and it is desired to develop a theory on how to blend coals and binders effectively. In this work the coal fractionation method proposed by the authors was applied to characterize coals and binders. Nine different-rank coals and two binders (HPC developed by Kobe Steel and ASP) that were heat-treated at 400°C in advance were separated into three fractions having different molecular weight by solvent extraction at 350°C. The chemical and physical properties of each fraction were found to be almost independent of the coal and binder types. Based on these results, it was clarified that the thermoplastic behaviors of the mixture of several coals and binders and the strength of their resulting coke can be correlated to the relative abundance of the fractions in the mixture. It is therefore possible to determine an appropriate blending ratio of coals and binders to obtain high-strength coke. This approach can be expected as a new blending theory which is applicable even to the low-grade coals that have not been used and newly-developed binders.
