EFFECTS OF WEATHERING OF COAL ON THE PROP ERTIES OF A HIGHLY LOADED COAL-WATER MIXTURE

Changes in properties of a highly loaded coal water mixture (CWM) by w eathering of feed coal were investigated. As the duration of weatherin g of the feed coal was increased, the maximum reachable concentration to obtain CWM with a viscosity of 1 Pa . s decreased and also the amou nt of sedimentation during two-week storage increased. It was found th at the amount of sulfate formed by oxidation of iron sulfide in the fe ed coal increased during weathering causing the acidification of the p roduced CWM. Hydrophilic functional groups on the coal surface were th us increased resulting in a decrease of ''free water,'' which is neede d for a good fluidity. It was considered that acidification and an inc rease of hydrophilic functional groups on the coal surface were the ma in causes of the degradation of coal slurriability.