Highly selective capture characteristics of magnetic wires in CHGMS method

Abstract

Centrifugal high gradient magnetic separation (CHGMS) concentrates fine weakly magnetic minerals at a high selectivity, which was achieved through a magnetic matrix dynamically rotating in a magnetic field. In this work, the highly selectivity capture mechanisms of magnetic wires rotating in uniform and alternating magnetic fields were comparatively described, including their magnetic field distributions and the magnetic forces required for the capture of the wires to magnetic particles. The capture mechanism was experimentally verified with a primary ilmenite concentrate assaying 13.04% TiO2, which was produced from pulsating HGMS process. It was found that the dynamically rotating wire was able to achieve significantly improved capture selectivity, in comparison with the static (quasi-static) one; for instance, when the rotation speed of the 3.0 mm wire was increased from 15 (quasi-static) to 120 rpm (dynamic) in the uniform magnetic field, the grade of captured ilmenite particles was significantly improved from 15.98% to 23.86% TiO2. In addition, the capture characteristics of rotating wire was related to the build-up pattern of centrifugal high gradient magnetic field; for instance, when the 3.0 mm wire rotated at 120 rpm and 40 mm radius, the wire in the alternating magnetic field produced a magnetic product with a high TiO2 grade of 29.86% at the expense of slightly reduced capture mass weight, and this grade was significantly superior to that (23.72% TiO2) produced from the uniform magnetic field. The conclusions from this investigation would provide valuable foundations for the development and application of CHGMS method.