Segregation and Process Features in a Teeter Bed Separator as Revealed by High-Speed Videography and Image Processing

Gravity concentration in a liquid fluidized bed floatex density separator (FDS) was investigated through high-speed videography and image analysis. Process performance in terms of yield and grade of the product for fine coal beneficiation in the FDS was established experimentally. The feed coal (?1.18 mm) with 36% ash was enriched to 24% ash at a mass yield of 65%. Coarsest underflow with a d₅₀ of 700 μm was obtained at 5.8 kPa bed pressure, 120 kg/h feed rate, and 12 lpm teeter water flow. The lowest SG₅₀ of 1.62 was obtained at 5.4 kPa, 15 lpm, and 80 kg/h. At 9 lpm water flow, steady state was achieved in 400 sec when the voidage and suspension density distributions became constant. From the suspension density distribution, the SG₅₀, 1.69 under this set of conditions, was estimated with reasonable accuracy. Increase in teeter water was shown to increase the time required for attaining steady state. It was established that particle size distribution at the bottom of the bed in the column offers a good indication of the separation performance. The influences of the operating variables on the axial steady state profile of the suspension density and voidage were also established. Image analysis is shown to be quite useful in collecting quantitative transient and steady state data that may be difficult to obtain otherwise. The process performances were adequately described using such transient and steady state observations.