Effect of the Cross-Sectional Geometry of the Mixed Particle Zone on the Spiral Separation Process and Its Structural Optimization

Cross-sectional geometry is of significance in determining the flow characteristics and the particles separation in spiral concentrators. The effects of the cross-sectional geometry within the mixed particle zone on the secondary flow and the separation process of hematite and quartz particles with a size of 89.5 µm were investigated via a computational fluid dynamics (CFD) approach. The optimization of the line segment slopes was conducted using response surface methodology (RSM). The results indicate that the peak radial fluxes and average radial velocities of the secondary flow are positively correlated with the corresponding line segment slope. The independent adjustment of line slopes in regions Ⅰ and Ⅱ, and the interaction of line slopes in regions Ⅰ and Ⅲ, influence the separation efficiency of hematite and quartz particles significantly. The separation performance of the experimental spiral concentrator with a cross-sectional profile of the optimized line segments for a feed of hematite and quartz with a size range of -100+75 µm is remarkably improved by nearly 5%. This study provides insights for the cross-section design of spiral concentrators for the effective separation of coarse-grained hematite and quartz.