Study on the Enhanced-Gravity Separation Characteristics of Copper Ore in a Spiral Trapezoidal Pipe

Abstract

To address the difficulty in separating low-grade, fine-grained and severely slimed copper ores, this study combines the advantages of enhanced-gravity separation technology and continuous separation in a spiral flow channel, and proposes an enhanced-gravity separation method using a spiral trapezoidal pipe. In this method, an enrichment section and a secondary sand-splitting section are arranged successively along the flow direction, forming a gradient separation structure. In the enrichment section, the centrifugal force field generated by the spiral flow channel promotes the preliminary enrichment of Cu particles. In the secondary sand-splitting section, local recirculation vortices and reverse radial flow are induced by abrupt cross-sectional expansion, thereby strengthening the separation of light and heavy particles. Fluent was used to numerically simulate the flow-field distribution, recirculation vortex evolution, particle distribution characteristics, and the influence of structural parameters on the separation performance of the spiral trapezoidal pipe under enhanced-gravity separation. The results show that the stable radial pressure gradient and relatively high tangential velocity in the enrichment section are conducive to the migration of Cu particles toward the outer enrichment wall. In the secondary sand-splitting section, the recirculation vortex first strengthens, then weakens, subsequently decays slowly, and finally disappears rapidly along the flow direction. The recirculation vortex in the front part strips SiO₂ particles from the surface layer of the particle bed, while the negative radial-velocity region at the bottom of the middle and rear parts further promotes the lateral entrainment of SiO₂ particles from the outer enriched bed toward the inner mainstream region. The particle volume fraction distribution indicates that Cu particles are mainly and stably enriched in the outer bottom region, whereas SiO₂ particles gradually migrate toward the newly formed cavity and the tailings side. The structural parameter analysis shows that when the spiral diameter is 260 mm, the pitch is 50 mm, and the boss width of the secondary sand-splitting section is 4 mm, the spiral trapezoidal pipe exhibits better separation performance, with a Cu recovery of 72.35% and an enrichment ratio of 10.51. The results can provide a reference for the enhanced separation of low-grade, fine-grained complex copper ores and the structural design of novel enhanced-gravity separation equipment.