Analysis of separation response of Kelsey centrifugal jig in processing fine coal

Abstract

Beneficiation of fine coal of size 300 × 150 μm was investigated in a laboratory Kelsey jig. A number of process variables were studied while others were kept constant. Silica sand of size − 1.68 + 0.85 mm was used as ragging material to prevent pegging of the internal screen. The thickness of the ragging bed was established to be most crucial in controlling the separation. Rotational speed significantly affected the porosity of the ragging bed and particle momentum which had a contrasting influence on process performance. Pulsation rate determined bed dilation and misplacement of heavier particles. A slip velocity based estimation of the particle momentum indicated that the passage of particles in the intermediate momentum region to the overflow or underflow determined the performance. In a single pass through the Kelsey jig an absolute 7% reduction in the ash content was achieved at over 55% yield. A thicker bed depth was found to facilitate rejection of high ash materials. Models were developed for the response parameters and optimization performed. Operating regimes were identified for roughing or cleaning application of the Kelsey jig for optimum performance. It was established that Kelsey jig could be effective in fine coal cleaning if operated in a controlled manner.