Effect of Hydrothermal Dehydration on the Slurry Ability of Lignite

[Image: see text] The high moisture content limits the large-scale utilization of lignite. Hydrothermal dehydration (HTD) has been confirmed as an effective method to improve the quality of lignite for further utilization. In this study, the effects of the changes in the lignite interface properties caused by the HTD modified final temperature on the slurry ability were investigated in the range of 160–200 °C. The results indicated that with the gradual rise of the HTD modified final temperature, the content of the carboxyl groups and phenolic hydroxyl groups on the surface of lignite decreased by 21.95 and 36.34%, respectively. In the meantime, the atomic ratio of oxygen/carbon, the content of equilibrium moisture, and the thickness of the hydrated film were reduced from 0.293, 14.63%, and 34.26 nm to 0.252, 9.43%, and 13.33 nm, respectively. Therefore, these changes of interfacial properties improved the slurry ability of lignite, with higher fixed-viscosity solid concentration, lower yield stress, increased pseudo-plasticity, and gradually decreased static stability of the prepared lignite coal water slurry. hydrothermal dehydration; slurry ability; oxygen-containing functional groups; hydrated film