Study on Separation and Dynamic Characteristics of Ilmenite and Chlorite Regulated by Structural Parameters of Spiral Chute

Based on a self-constructed numerical model of the spiral chute (Eulerian multi-fluid VOF model coupled with the Bagnold lift force model), this study systematically investigates the effects of structural parameters (downward bevel angle and pitch-diameter ratio) on the separation performance of ilmenite and chlorite. A comprehensive analysis is conducted on the evolution of particle motion behavior, force characteristics, and flow field features, and the reliability of the simulation results is validated through actual ore separation tests. The findings demonstrate that structural parameters exert a significant regulatory effect on the separation efficiency of the two minerals. Under the conditions of a downward bevel angle of 12° and a pitch-diameter ratio of 0.6, for a mixed feed with a TiO2 grade of 8.20%, favorable concentrate indices are achieved within a splitter location range of 111.97–149.24 mm, yielding a TiO2 grade of 27.45%–35.89% and a recovery of 91.45%–99.97%. The separation efficiency of coarse ilmenite particles is superior to that of fine ilmenite particles, whereas the separation performance of chlorite improves with decreasing particle size. The fine-particle system exhibits greater sensitivity to variations in structural parameters. Ilmenite particles follow a migration path characterized by initial outward movement followed by inward movement, while chlorite particles continuously migrate outward. The distribution differences between the two minerals in the middle region of the trough surface are significant, and the enrichment of 56 μm chlorite in this region may exacerbate intermingling. Increasing the downward bevel angle or decreasing the pitch-diameter ratio enhances the shear rate of the flow field, amplifies the lifting effect of the Bagnold force on chlorite particles, and significantly thickens the flow film from the inner edge to the middle region. These adjustments promote the formation and stabilization of secondary circulation, thereby increasing the radial flux of the inner circulation cell and optimizing the enrichment behavior of ilmenite in the inner trough region. The actual separation tests validate the reliability of the simulation results. The findings provide a theoretical basis and process guidance for the structural optimization of spiral chutes and the efficient separation of fine ilmenite particles.