Particle motion under turbulent eddies: Inspiration for fine minerals flotation

Abstract

Turbulent flow ubiquitous in flotation machines and contain multi-scale eddies. Compared to static environments, turbulence can increase particle kinetic energy and promote particle-bubble collision in mineral flotation. However, there have been few quantitative studies on turbulent eddies that affect particle motion, which limits the precise flow control of flotation processes. In this study, the motion characteristics of particles in isotropic turbulence were measured by particle tracking velocimetry, and the relationship between turbulent eddy and particle motion was quantitatively analyzed by 7-scale wavelet transform and fast Fourier transform. The measurement results show that the particle moves upward following a rotating turbulent eddy, and turbulent eddies with sizes of 35–119 µm and 127–288 µm drives the motion of d_p = 74 µm and d_p = 200 µm particles respectively. The turbulent acceleration of particles within a turbulent eddy can be calculated as $a_{\lambda }=C{\epsilon }^{2/3}{\lambda }^{-1/3}$. This study provides an eddy control basis for mineral flotation performance improvement.