Optimization of Ultrafine Grinding Parameters Guided by Process Mineralogy to Improve Iron Separation Efficiency of titano-magnetite in Magnetic Separation

Grinding operations play a pivotal role in enabling the effective separation of minerals, as it directly dictates the degree of mineral liberation and a critical prerequisite for subsequent beneficiation processes. In this study, a combination of advanced analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), and the Advanced Mineral Identification and Characterization System (AMICS), was employed to systematically investigate four key aspects: (1) the mineral composition of the raw ore, (2) the grain size distribution of valuable minerals, (3) the degree of ionization, and (4) the intracrystalline relationships of titano-magnetite with other coexisting phases. The results indicated that titano-magnetite exhibits a strong associative relationship with gangue minerals (e.g., chlorite, pyroxene, and amphibole). This intimate association causes complete dissociation of titano-magnetite from gangue minerals to be challenging during grinding. Consequently, gangue minerals are prone to entrainment in the iron concentrate alongside titano-magnetite, which subsequently compromises the quality of the final iron concentrate. Based on the aforementioned mineralogical characteristics of titano-magnetite, the high-speed stirred mill was used to achieve the ultra-grinding of titano-magnetite and optimize operation parameters. The optimal grinding conditions were ultimately determined as follows: stirred speed of 2000 r/min, grinding concentration of 35%, feeding frequency of 5 Hz, and media filling ratio of 70%. Under these optimized conditions, an optimized magnetic separation process to improve the recovery of high-content iron concentrates from titano-magnetite was performed, eventually allowing the iron grade to reach 56.25%. This study provides crucial insights into addressing the issue of complex titano-magnetite, and the optimized grinding-magnetic separation process proposed herein offers theoretical and technical guidance for scaling up beneficiation operations in industrial settings, thereby facilitating the sustainable utilization of titano-magnetite resources.