Selective Classification of Mineral Sand Slimes in an Air Fluidized Bed

Abstract

Studies were carried out for selective classification of mineral sands to remove unwanted slimes (particles of <0.63 µm in size). Vertical and arched fluidized bed setups were tested to retain the coarser heavy mineral particles from fluidized mineral sand beds. Theoretically calculated process parameters were used to develop the experimental setups. The mathematical model given by Nguyentranlam and Galvin (“Particle classification in the reflux classifier.” Minerals Engineering, 14(9), 2001, pp. 1081–1091) was used to develop an arched fluidized bed setup. Experiments were carried out at six different superficial air velocities (0.21, 0.25, 0.34, 0.41, 0.64, and 0.82 m/s) in the vertical and arched fluidized bed setups. An acceptable agreement was found in the experimental and theoretical results. The overall process capability of the vertical fluidized bed to selectively remove the slimes was 44.8% with the loss of 3.93% of heavy minerals. The overall process capability was improved up to 52% with the loss of 4.08% of heavy minerals by the proposed arched fluidized bed setup. The developed arched fluidized bed setup showed improved performance for selective elutriation of mineral sand slime particles with compromising heavy mineral losses.

Keywords:

• air fluidization
• elutriation
• mineral sand slimes
• terminal velocity