Study on the effect of autogenous medium characteristics on oil shale beneficiation in the compound autogenous medium dry cleaning apparatus

Abstract Oil shale is considered to be the optimal alternative energy sources due to its large reserves and high oil content. However, it is accompanied by large quantities of inorganic mineral impurities in the mining and should be beneficiated firstly. It could be effectively separated from inorganic mineral impurities by physical cleaning. In this study, the migration and diffusion behavior of autogenous medium particles in the compound dry cleaning bed were investigated. The effects of operating parameters on the stability of the bed density of the autogenous medium were systematically analyzed. The density distribution characteristics of autogenous medium bed and the distribution and stratification of oil shale particles in the autogenous medium bed were investigated. The results show that the density of the fluidized bed formed by the autogenous medium particles is uniform and stable. The oil content of the particles in each layer fluctuates from 1% to 1.04% in the direction of axis Z. The uniformity and stability of the bed density are optimal when the particles of 0 to 1.5 mm are the dominant autogenous medium. The σρ of the bed density reaches the minimum value when the vibration amplitude (A), frequency (f) and airflow (Uv) are 3.4 mm, 44 Hz and 0.17 m/s, respectively. The σρ is minimum of 0.011 g/cm3 and the uniformity and stability of the bed density are optimal when the content of the lower density particles of 0–2.0 g/cm3 and higher density particle of +2.3 g/cm3 are 35% and 55% separately. Under the optimal operating parameters, the rapid settlement and stratification zone for concentrate, transition zone of separation for middlings, and circulating transportation zone for tailings are obtained along the transverse (X-axis) direction of the bed. The content of oil and half-coke and the yield for the concentrate are 10.13%, 67.49% and 43.3%, separately and the oil content, half-coke content and the yield of the tailings are 0.85%, 98.65% and 56.7% respectively when the Uv, A, f, T are 0.165 m/s, 3.4 mm, 44 Hz and 24 s separately. The probable error of E is 0.065 g/cm3, which illustrates that the concentrate of the oil shale can be efficiently enriched.