Direct Coal Liquefaction Residue Improves the Slurryability of Lignite Through Co-Slurry and Microwave Co-Pyrolysis

Abstract

This study mixed direct coal liquefaction residue (DCLR) with lignite to prepare mixed slurry and used DCLR as a microwave absorber to enhance lignite pyrolysis. Discussed the influence of DCLR on lignite slurryability changes and microscopic mechanisms in two different ways: physical blending and chemical modification. The results show that: as the increase of lignite/DCLR mass ratio decreased from 10:0 to 5:5 the maximum solid concentration (MSC) of the mixed slurry increased from 42.14 wt% to 53.84 wt%, the pseudoplasticity and static stability gradually decreased. And during microwave pyrolysis process with the assist of 12 wt% DCLR the slow drying stage was shortened, and the constant temperature stage was extended, thus, the coal quality was improved, the oxygen-containing functional groups was removed significantly; the BET specific surface area increased and the original macropores gradually converted into mesopores and micropores. These changes caused the slurryability of UL to be improved significantly: the MSC increased to 64.54 wt% (S 5 ), the “shear-thinning” characteristic became less obvious, and the static stability became worse. Therefore, DCLR could effectively improve the slurryability of lignite through co-slurry and co-pyrolysis under microwave field.