Improve the slurry ability of lignite through co-slurrying and microwave co-pyrolysis with direct coal liquefaction residue

Abstract

This study is devoted to demonstrating experimentally the advantages of direct coal liquefaction residue (DCLR) on improving the slurry ability of lignite through co-slurry and microwave co-pyrolysis. The results show that: as the lignite/DCLR mass ratio decreased from 10:0–5:5 the maximum solid concentration (MSC) of the mixed slurry increased from 42.14 wt% to 54.25 wt%, simultaneously, the pseudoplasticity and static stability gradually decreased. This is because the organic matter and abundant minerals in DCLR remarkably changed the slurry ability of mixed slurry. And during microwave pyrolysis with the assist of 12 wt% DCLR the slow drying stage of lignite pyrolysis was shortened, and the constant temperature stage was extended, thus, the coal quality was improved, the oxygen-containing functional groups was removed significantly and the BET specific surface area increased. These changes caused the MSC of upgraded lignite water slurry (ULWS) increased to 64.54 wt%; but the “shear-thinning” characteristic became inconspicuous, and the static stability became slightly worse. In general, DCLR could effectively improve the slurry ability of lignite through co-slurry with lignite at a mass ratio of 5:5 and co-pyrolysis with lignite at a microwave power of 1000 W.