Research on the Magnetic Field Distribution Characteristics of Rhombic Magnetic Matrices in Superconducting HGMS and Its Separation Behavior on Low-grade Zinnwaldite Ore

The rapid development of the battery and energy storage industries has led to a significant consumption of lithium resources. The efficient utilization of low-grade lithium resources has become a research hotspot. In this study, it was proposed for the first time to adopt superconducting high-gradient magnetic separation technology for the efficient separation of low-grade zinnwaldite ore. Besides, the induced magnetic field distribution of rhombic magnetic matrices in superconducting magnetic field was investigated through numerical simulations. Both single matrix and multi-matrix composite system were considered, and the rhombic magnetic matrices separation behavior on zinnwaldite ore was evaluated using the superconducting high-gradient magnetic separation (SD-HGMS) test. The numerical simulation results showed that for the single matrix, as the matrix size increases, the range of the induced magnetic field expands, while the magnetic induction and the proportion of the adsorption area on the matrix surface gradually decrease. For multi-matrix composite systems, the structural characteristics of the matrices significantly affect the distribution of induced magnetic fields between adjacent matrices, indicating strong magnetic field interactions. As the matrix long-axis size increases and the vertical spacing decreases, the magnetic field superposition effect leaded to a decrease in the magnetic field gradient and magnetic force. SD-HGMS experiments further demonstrated that the SD-HGMS process could efficiently separate zinnwaldite from low-grade zinnwaldite ore, with a magnetic separation recovery rate of over 93% in the 3.0T background magnetic induction intensity. The experiments also indicated that the filling rate and matrix size substantially influenced the separation performance. Besides, increasing the vertical spacing reduces the filling rate and adsorption area, thereby decreasing the Li2O recovery and concentration efficiency. Similarly, larger matrix sizes lower separation efficiency due to weakened magnetic forces and reduced effective adsorption areas. This research provides data support for the development of superconducting high-gradient magnetic separation technology and the efficient exploitation of low-grade lithium mineral resources.