Cleaning of the moist fine grained oil shale in the compound dry separator and the diffusion of the external moisture of the oil shale

Abstract Oil shale is a crucial alternative energy resource. The external moisture content of the fine grained oil shale is high and the grade is decreased. The physical separation can effectively remove inorganic impurities and the external moisture to enrich the concentrate. In this study, the external moisture diffusion process and its effects on the diffusion behavior of the moist fine-grained oil shale in the compound dry separator were studied. The effects of the operating parameters (vibration amplitude, vibration frequency and airflow) on the external moisture migration process were studied and the optimal parameters were obtained. The results illustrate the external moisture content decreases along the X-axis in the upper layer, but shows fluctuation in the central of the bed, and they are concentrated in the central area of the bed and loosely distributed in the side wall. The external moisture content also decreases gradually in the Y axis direction. The decrements of the external moisture content in the lower layer is greater than that in the upper bed as the particles in the lower bed is firstly affected by the airflow. With the increasing of the airflow, vibration amplitude and frequency, the standard deviation σmf of the external moisture content decreases firstly and then increases. When the vibration frequency (f), vibration amplitude (A) and airflow (Uv) are 54 Hz, 3.2 mm and 2.45 m/s, the removal rate of the external moisture is optimal. Under this condition, the probable error E value is 0.10 g/cm3 with the optimal dehydration and separation results.