In this paper, the performance of a hydrocyclone is investigated using Computational Fluid Dynamics coupled with the Discrete Phase Model to predict the trajectories and fate of solid particles. The working fluid is water mixed with ferromagnetic powder, giving an effective density of 2850 kg/m³. Solid particles injected into the hydrocyclone include copper (density 4000 kg/m³) and rock (density 1800 kg/m³), both with a diameter of 25 mm. The results showed that all copper particles were discharged from the underflow as predicted. However, a considerable fraction of rock particles, due to their lower density relative to the fluid, were trapped within the flow field and released through the upper outlet (vortex finder), which is undesirable for the separation process. To improve performance, several geometric modifications were applied: extending the vortex finder (upper outlet pipe), converting the inlet cross-section to a rectangular shape while keeping the hydraulic diameter constant, and increasing the length of the conical section. After geometry refinement, simulations were performed by injecting a larger number of particles (1398 copper and the same amount of rock). The results indicated significant improvement: rock particles discharged through the upper outlet decreased by about 3%, and those leaving through the underflow increased by approximately 40–50% compared to the original design. These findings demonstrate that increasing the vortex finder length and optimizing inlet and cone geometry enhance the swirling field and improve the settling rate of lighter particles.