ABSTRACT
To facilitate the microwave upgrade of lignite and increase the solid concentration of lignite water slurry (LWS), lignite semi-coke was used as a microwave absorber. Some properties of lignite before and after microwave upgrade were studied by infrared spectroscopy (FTIR) and low-temperature nitrogen adsorption. Besides, the adsorption characteristics and slurryability of upgraded lignite were investigated, respectively. It turned out that adding lignite semi-coke could effectively accelerate the process of lignite microwave upgrade; and as the irradiation power increased, the moisture content, carboxyl, and hydroxyl functional groups were removed obviously, the pore structures changed, and the number of mesopores and micropores increased from macropores transition. These changes improved the adsorption characteristics of upgraded lignite. Therefore, the above changes enhanced the slurryability of upgraded lignite: the maximum solid concentration (with an apparent viscosity at 1000 mPa.s) of LWSs increased from 49.49wt% (prepared from raw coal) to 63.90wt% (prepared from upgraded lignite at 1100 W), and the pseudoplasticity of LWSs gradually weakened.