Abstract: Basic on vibration mechanical thermal expression dewatering experiments, effects of temperature, pressure and vibration force on the pore structure variation of lignite were studied. The porosity of lignite decreased with increasing temperature, pressure and vibration force. The increase of vibration force in a special range (1-4 kN) resulted in more severe reduction of porosity of lignite than that out of the range. The pore size distributions of lignite were significantly changed by vibration mechanical thermal expression dewatering process. The pores filled with water collapsed and developed to smaller pores as water being gradually removed with increasing temperature and pressure, resulted in the severe reduction of inter-particle pores and macro-pores and slightly increase of meso-pores. The inter-particle pores also could be reduced by the more closely arrangement of particles and the change of particle structure caused by vibration force. The mean pore diameters of lignite significantly decreased with the increase of temperature and pressure. The specific surface areas of lignite slightly decreased under 100 ℃ and 5MPa, and then slightly increased. The vibration force had little effect on mean pore diameters and specific surface areas of lignite.

Key words: lignite, pore structure, dewatering, Vibration Mechanical Thermal Expression