Efficient dehydration of waste coal gasification slag based on particles tight stacking and pore channel drying: A dehydration energy cascade adaptation strategy

Effective dehydration of waste coal gasification fine slag is the premise of its large-scale resource utilization. In this manuscript, the waste gasification fine slag filter cake with 50 % moisture content is selected as the research object. The dehydration characteristics of waste coal gasification fine slag based on combined “mechanical extrusion-hot air/microwave drying” are studied. The mechanical extrusion strength varies from 22.5 MPa to 90.0 MPa which causes the increasing of filter cake density from 1.4 to 1.65 cm3/g. The particles tight stacking can compress the water occurrence space and improve the water removal ability. The effective boundary value, particle size evolution and energy action mechanism of the mechanical extrusion dehydration process are analyzed systematically. The pore channel drying characteristics and kinetic analysis above filter cake under 140 °C hot air drying and 160W microwave drying are also studied, and the drying energy mechanism and kinetic parameters of these two drying processes are compared. Moreover, the real-time energy consumption of the two drying processes are calculated, and the 160W microwave has higher dehydration efficiency and energy saving advantages. The combined mechanical extrusion-microwave drying is proposed, which would improve the cascade removal effect of intergranular water and pore water. This study will provide theoretical guidance for efficient dehydration of waste coal gasification fine slag, which is benefit for waste slag large-scale disposal and environmental protection.