Surface-coating Improves The Coal Water Slurry Formation Of Low Rank Coal And Biomass

Shendong Shangwan coal is a low rank coal from Inner Mongolia China. Shendong Shangwan coal particles show electronegativity in the slurry, as there are many oxygen functional groups on the surface and in the core of the particles, such as carboxyl group, hydroxyl group and carbonyl group. Besides, as these functional groups are all hydrophilic, Shendong Shangwan coal has very strong water retaining capacity. The CWS made from Shendong Shangwan coal could contain little free water and the CWS coal concentration is low. In this paper, we used four different chemicals to coat the surface of Shendong Shangwan coal and investigated the corresponding effects on slurry preparation. Experiments of contact angle indicate that these methods could improve the hydrophobicity of the coal surface. The physical characteristics of coal particle are change, because the surfactants cover with the coal. The zeta potential confirms that the hydrophilic groups on the Shendong Shangwan coal’s surface could not combine with water, as the surfactant separates water from the hydrophilic groups on the coal’s surface. The surfactants play an important role in cut down the functional groups on the surface of coal.In this paper, the rice-stalks were dried and powdered. Then certain amounts of the rice stalk powders were mixed with coal to prepare the biomass coal-water-slurries. Influence on the slurry ability and stability of biomass CWS with different type and dosage of additives, and different shear rates were studied. The results show that the slurry ability is not that pleasant when added the sole ionic or non-ionic surfactants in biomass CWS, and we find that the higher dosage used, the higher apparent viscosity of biomass CWS is. However, the slurry ability of biomass CWS was improved after using mixed surfactant with ionic and non-ionic surfactants at a range of different percentage, the optimum scheme:MF:ST=4:1and MF:02=6:1.