Upgrading of 6–0 mm low rank high sulfur lignite by a compound dry cascade separation bed

In this paper, the effect of vibration intensity on the spatial distribution of sulfur content in bed particles was studied. The effects of vibration and airflow on the mechanical characteristics of particles were studied, the collision behavior mode of particles was determined, the spatial saltation law of particles was investigated, the spatial functional axis of beds was determined, and the saltation separation period of particles was determined. The test results show that: When separation bed provides inlet airflow velocity (U_in) is 2.55 m/s, the airflow distribution interval of I, II and III areas were U_I=2.55–2.57 m/s, U_II=1.33–1.35 m/s, U_III=0.35–0.38 m/s, respectively; when separation bed vibration amplitude (A) A=2.4–2.5 mm, separation bed vibration frequency (f) f=23–24 Hz, the desulfurization effect is the best. When vibration intensity (Γ) Γ=1.22, U_in=1.05 m/s, the particles have disordered contact and collision behavior. When Γ=14.89, U_in=3.18 m/s, the particles have a transition cataclastic collision. When Γ=5.80, U_in=2.55 m/s, the particles have directional collision behavior. It is determined that the OX axis is the transverse stable diffusion axis of the material, the OY axis is the longitudinal gradient transport axis of the material, and the OZ axis is the vertical density cascade distribution axis of the material. When separation time (T) T=0–10 s was the period of disorderly diffusion and mixing of particles, T=10–20 s was the period of directional migration and stratification of particles, and T=20–30 s was the period of cascade distribution and separation of particles. Finally, separation experiments conducted under optimal operating parameters demonstrated that the clean coal yield was 72.02% with a sulfur content of 0.98%.