Performance characterization and misplacement studies of liquid-solid fluidized bed density separator for coal beneficiation using Taguchi-ANOVA method

Coal preparation plants commonly use density-based separators to remove high-density inorganic matter (rock) from low-density carbonaceous matter (coal). Liquid-solid fluidized bed separators (FBS), segregates particles with different size, shape, and density. Particles with different terminal velocities report to various heights of the fluidization column. This property has been used to beneficiate the low-grade coal particles. As the material systems in mineral processing vary broadly in physical characteristics, misplacement of particles to an undesired destination is a prevalent occurrence. The present work aims at understanding the influence of input variables on the separation performance and particle misplacement in FBS. Quantitative and qualitative analyses of the performance characteristics and misplacement have been studied using Taguchi statistical design and ANOVA. Misplacement and normalized misplacement indexes were calculated to quantify the extent of misplacement during segregation. The optimized mean separation efficiency was obtained at optimized combination of mean particle size of 400 mu m, bed height of 20 cm, superficial velocity of 2.83 cm/s, and overflow tap height of 12 cm, whereas the optimized mean normalized misplacement index was obtained at mean particle size of 400 mu m, bed height of 20 cm, superficial velocity of 2.12 cm/s, and overflow tap height of 12 cm.