Pulsation curves strengthen the high gradient magnetic separation process Ⅱ: Consideration of separation performance

Abstract

The use of pulsating slurry has been found to be effective in overcoming matrix blockage and improving separation selectivity in high gradient magnetic separators (HGMS). The velocity of the pulsating slurry is regulated by a sinusoidal cycle function, which causes the downward velocity to be much greater than the upward velocity due to the superposition of the sinusoidal pulsation velocity and the feeding velocity. However, the unbalanced velocity configuration in the up-downward stroke limits separation efficiency. This paper investigates the use of asymmetrical pulsation curves in a lab-scale HGMS to balance the velocity configuration and consequently improve separation performance. Magnetic field strength, feed velocity, and pulsating frequency were varied in separate experiments to determine the effect of pulsation curves on separation performance. The asymmetrical pulsation curve with a faster upward stroke and slower downward stroke was found to achieve a TiO2 concentrate grade of 23.94 %, a recovery of 66.78 %, and a separation efficiency of 50.46 % for the separation of ilmenite. When the concentrate grade is slightly higher, this new curve shows an increase of 5.68 % in recovery and 5.05 % in separation efficiency compared to the conventional sinusoidal pulsation curve. This improvement is attributed to a simultaneous strengthening of the material loose-adsorption process by separately regulating the pulsating upward and downward strokes.