Effects of Ferrosilicon Fineness on the Multiphase Flow Field and Separation Performance of Dense Medium Cyclones for Low-Grade Ores

As natural resources continue to be exploited, dense medium cyclones (DMCs) are increasingly utilized for the preconcentration of low-grade ores to meet the demands for higher feed grade, increased processing capacity, and reduced energy consumption. However, determining the optimal fineness of ferrosilicon remains ambiguous for different types of ores and is often described as more of an art than a science. This paper investigates the subtle effects of ferrosilicon fineness on flow field characteristics, medium classification, and the ore separation process using a validated numerical approach, which integrates a two-fluid model, a turbulence dispersion model, and a discrete phase model. The results reveal that, under consistent operating conditions, increasing the ferrosilicon fineness enhances the tangential velocity and pressure drop while having minimal impact on axial velocity and water split. The ferrosilicon fineness also influences the distribution of the turbulence field, and in combination with the changes in the particle size distribution (PSD) itself, it modifies the characteristics of the density field. This results in a reduction in the density difference between the overflow and underflow with finer ferrosilicon particles, thereby lowering the cut density but improving the separation accuracy. Moreover, the residence time of particles with different densities in the DMC also varies significantly with changes in separation density. The study underscores that even minor changes in ferrosilicon fineness can impact separation performance, highlighting the need for careful consideration of this factor in process design and medium recovery.