An Australian low rank coal (Loy Yang coal) was upgraded by hydrothermally-treated process at 150-350℃. The change of surface properties in treated coal was examined. The hygroscopicity and content of carboxyl group remarkably decreased. The specific surface area of coal decreased as heat treatment temperature (HTT) was raised. The slurriability of CWM, which prepared from treated coal, was much improved. The coal concentration of CWM, which has a viscosity of 1.0 Pa・s, was 34wt%/CWM; whereas that for the 350℃-treated coal was 59wt%/CWM, and the 350℃-treated coal CWM have good storage stability.
