Pre-concentration of Complicated Rare-earth Mineral Bearing Ore by Wet Electromagnetic Separation and Superconducting Magnetic Separation

To investigate the pre-concentration of rare-earth minerals from a complicated rare-earth minerals bearing ore in Inner Mongolia using magnetic separation, two different magnetic separation methods, conventional wet electromagnetic separation and superconducting magnetic separation, were employed. The effects of background magnetic induction intensity, magnetic medium gap parameters, pulp flow rate and feeding particle size on index of rare-earth concentrate were investigated in wet electromagnetic separation. The effects of background magnetic induction intensity, steel-bar diameter, pulp concentration and feeding particle size on index of rare-earth concentrate were investigated in superconducting magnetic separation. The results show that for wet electromagnetic separation, the suitable pre-concentrated conditions that the background magnetic induction intensity of roughing of 0. 5 T, the background magnetic induction intensity of scavenging of 1. 4 T, the magnetic medium of 1. 5 mm box-type toothed plate, the pulp flow rate of 50 mL/s, the feeding particle size of - 0. 075 mm accounting for 50% are obtained. For superconducting magnetic separation, the suitable pre-concentrated conditions that background magnetic induction intensity of 5 T, magnetic medium of 1.5 mm steel bar, pulp concentration of 15%, feeding particle size of - 0. 075 mm accounting for 60% are obtained. Compared with one roughing and one scavenger process of wet electromagnetic separation, the pre-concentration index of concentrate with a REO grade of 2.855%, a REO recovery of 92.82% and tailings of 66. 74% is obtained by one roughing separation of superconducting magnetic separation. By the pre-concentration process of superconducting magnetic separation, a large number of gangue can be rejected to reduce the separation cost, which shows that superconducting magnetic separation has a good intensity and selectivity for the concentration of rare-earth minerals. The pre-concentrated products were analyzed and characterized by means of X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and scanning electron microscope (SEM). XRD results suggest that the content of gangue in superconducting magnetic separation concentrate is relatively low, and rare-earth minerals can be pre-concentrated effectively by superconducting magnetic separation. VSM results suggest that the maximum specific magnetic susceptibility of superconducting magnetic concentrate is 4. 299 × 10-6m3/kg, slightly stronger than that of wet electromagnetic concentrate, which shows that the concentration degree of magnetic products in superconducting magnetic separation is better than that in wet electromagnetic separation, and the content of weak magnetic minerals in wet electromagnetic separation concentrate is low. SEM results suggest that the valuable mineral intergrowths with weaker magnetic susceptibility can be captured by the superconducting magnetic to realize an efficient pre-concentration of rare-earth minerals, resulting from its capability of generating higher magnetic induction intensity. The results of this paper provide basic research data for realizing the low-cost development of this type of ore. © 2022 Atomic Energy Press. All rights reserved.