Coal gasification coarse slag (CGCS) has become a bulk solid waste that threatens the ecological environment. The high moisture content of carbon-rich coal gasification coarse slag (CR-CGCS) seriously limits the subsequent treatment and utilization of CR-CGCS. In this study, a method of promoting the release of pore water by grinding was proposed, and surface modification was simultaneously performed in the process to promote the dewatering of CR-CGCS. Hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and kerosene was respectively added during grinding process. The results showed that kerosene can improve the dewatering efficiency of CR-CGCS more significantly than CTAB and SDS. The final moisture content of the CR-CGCS could be reduced from 47.50% to 33.01%. The mechanism of dewatering improvement was analyzed by SEM, FTIR, PVM and LF-NMR. The SEM and FTIR results illustrated that kerosene could reduce the content of oxygen-containing functional groups on the surface of CR-CGCS more effectively than CTAB and SDS. Meanwhile, PVM results showed that CR-CGCS modified by kerosene tended to form hydrophobic agglomerates. The LF-NMR results indicated that only the water in the macropores of CR-CGCS could be released in grinding process, but the water in micropores could be reduced when kerosene, CTAB, or SDS was added. This study provides a new insight for the deep dewatering of CR-CGCS and theoretical support for the efficient utilization of CR-CGCS.

carbon-rich coal gasification coarse slag; moisture content; surface modification; grinding; dewatering