Direct Coal Liquefaction Residue (DCLR) is a main byproduct inevitablyproduced in direct coal to oil liquefaction(DCOL), accounting for 30% of the totalcoal by weight. Composed of heavy oil, asphaltene preasphaltenes, andtetrahydrofuran insoluble, DCLR possesses high amounts of ashes, sulfurs,carbons, and calorific value, of which the heavy oil and asphaltene takes about30%~50% by weight. Efficient utilization of DCLRcould reduce environmental pollution and make a huge influence on thethermal and economical efficiency of DCOLprocesses. Therefore, how to reuse DCLR is an importantissue to DCOL processes.
Since the 1970s, how to reuse DCLR has started tobe investigated. Lytle et al.found that during DCOL process a high amount of DCLRwas produced and they further studied the characteristics of DCLR.Khare andSuganom et al.presented the basic structure and pyrolysis propertyof DCLR. Tanaka et al.proved the molecularstructure of raw coal in DCLR .
In summary, it is generallyconsidered that DCLR could be reused as an asphalt modifier, intermediateasphalts, etc. Most researches werefocused on the effect of adding DLCR on asphalts, not on the properties ofasphalt mortar and asphalt mixtures. Based on the mortar theory, itis well known that asphalt mixture is a dispersion system with a multilevelspace network structure, in which asphalt mortarplays a most important role in the performance of asphalt mixture. Thecomposition and filler/asphalt ratio of asphalt mortar determine the high/low temperature performanceof asphalt mixture. When thefiller/asphalt ratiois too small, the free asphalts are toomuch and the binding between asphalts with coarse or fine aggregatesis weak. While the filler/asphalt ratio istoo big, the free asphalts are totally absorbed by mineral fillersand asphalt mortar becomesbrittle and stiff due to lack of asphalt as a medium and consequently thebinding becomes weak. Only with an appropriate filler/asphalt ratio, theoptimal binding strength of asphalt mortar can be obtained .