Effect of hydrothermal dewatering on physicochemical properties and moisture re-adsorption capacity of a lignite

The effects of hydrothermal dewatering (HTD) on physicochemical properties and moisture re-adsorption capacity of Zhaotong lignite were analyzed. The results showed that HTD could improve the quality of lignite. During the process of HTD, oxygen-containing functional groups decomposed. Both high temperature and pressure favor the formation of large pore volume and small pore diameter. Treated temperature was the key factor governing the moisture re-adsorption capacity of lignite. The moisture re-adsorption degree decreased from 12.47% to 6.13% when the temperature varied from 200 to 300°C. While, the pressure had weaker effect on the degree of moisture re-adsorption.