Influence of conic shape on bypass and cut-size in hydrocyclones

Hydrocyclones in ball-mill classifier circuits have traditionally faced the challenge of fines bypass, driving the exploration of alternatives such as screens. However, our study demonstrates that optimizing hydrocyclone design, specifically with convex-conic geometry, can achieve lower bypass with coarser cut sizes. Through a combination of Computational Fluid Dynamics (CFD) simulations and lab-scale experiments, we consistently observed that convex-conic hydrocyclones deliver coarser cut sizes and lower bypass rates compared to standard hydrocyclones across a range of flow rates. CFD results revealed that convex designs exhibit distinct flow characteristics, such as higher axial velocities near the apex and lower radial velocities at the center, and lower tangential velocities creating a favorable environment for particle classification and reducing fines bypass with coarser cut size. Experimental findings confirmed these trends, with the convex design achieving lower underflow recoveries and reduced bypass at all tested flow rates. For instance, at a flow rate of 1000 mL/s, the convex hydrocyclone reduced fines bypass to 18.6%, compared to 24.6% for the standard design, while producing a coarser cut size of 94 μ m versus 78 μ m . These findings prove that convex-conic hydrocyclones offer superior performance, making them a cost-effective alternative to screens.