High gradient magnetic separation in centrifugal field

Abstract

High gradient magnetic separation (HGMS) in centrifugal field, termed a Centrifugal High Gradient Magnetic Separation (CHGMS), has been developed to concentrate fine weakly magnetic particles such as hematite and ilmenite. In this investigation, the principle of CHGMS is theoretically discussed and a cyclic pilot-scale CHGMS separator was tested to concentrate a fine (−74μm) hematite ore, to study the effect of key variables such as magnetic induction, rotation speed of matrix, feed flow rate and feed mass on the separation performance of the separator. The results of investigation indicate that changes in the magnetic induction and the rotation speed of matrix had the most significant influences on the performance. An increase in the rotation speed improved concentrate grade but reduced iron recovery, while the reverse was observed for changing the magnetic induction. A too low feed flow rate resulted in an extremely high recovery but a lower concentrate grade. For a given matrix configuration, there was an upper limit for feed mass as the capture area of magnetic elements in the matrix was fixed, and this limit was correlated to the rotation speed of matrix. When the variables were optimized, the CHGMS separator achieved a superior separation performance to pulsating HGMS, achieving a separation efficiency of 72.50% compared to 56.41%, respectively. It was thus concluded that the CHGMS provides a potential technique for the production of high-grade magnetic concentrate from fine weakly magnetic ores.