Effect of microwave irradiation on the slurrying ability of Ximeng lignite

The improvement of slurrying ability of Ximeng lignite under microwave irradiation was investigated. The effects of irradiation time and microwave power were discussed and the coal properties, particle size distribution, surface micro-topography, microscopic pore structure were analyzed. The results suggest that, with increasing irradiation time and microwave power, the final temperatures of coal samples increase. The moisture content of coal samples, which decreases from 17.13% (raw coal) to 1.07% after treatment at 900 W for 6 min, is dramatically removed under microwave irradiation. After processed by microwave irradiation, the coal particle surface gradually become smooth and regular; the particle size distribution of coal samples easily exhibits bimodal distribution; the BET surface area of coal samples differently decreases; the average pore diameter and pore volume differently increases. The increasing irradiation time and microwave power are good for the improvement of the maximum solid loading of brown coal, which increases from 50.13% (raw coal) to 54.68% after irradiating at 900 W for 6 min. With increasing irradiation time and microwave power, the unit energy consumption for inherent moisture removal first decreases and then increases and the minimum unit energy consumption of 1.82 kW·h/(kg moisture) for inherent moisture removal is obtained at 800 W for 3 min, the unit energy consumption for coal water slurry concentration promotion by 1% increases and the minimum unit energy consumption of 0.023 kW·h/(kg coal) for coal water slurry concentration promotion by 1% is obtained at 800 W for 1 min. ©, 2015, China Coal Society. All right reserved.