Influence of the propagation of three phase contact line on flotation recovery

Froth flotation is considered the most effective process of beneficiating low grade ores and is widely used in the base metals industry. For effective flotation, the attachment of mineral particles to air bubbles is important and has been studied by many researchers by measuring quantities such as attachment time, film-thinning time and induction time. This paper identifies an important step in the bubble–particle attachment process, namely, the expansion mechanism of the three phase contact (TPC) line between liquid, solid and air. It has been shown that the TPC expansion time is determined by the drainage of the surrounding fluid. It is influenced by factors such as pulp chemistry surrounding the particle, variations in surface forces and pressure inside the bubble. It has been observed experimentally that the TPC expansion time bears square root relationship to attachment efficiency. In this work, it has been argued that the attachment efficiency is related to the TPC circle radius propagation.     

Numerical analysis of hydrocyclones with different vortex finder configurations

This paper presents a numerical study of the multiphase flow and performance of hydrocyclone by means of two-fluid model, with special reference to the effects of diameter, length and shape of vortex finder at a wide range of feed solids concentrations. The considered shapes include the conventional cylindrical style and the new conical and inverse conical styles. The simulation results are analysed with respect to cyclone flow and performance in term of cut size d₅₀, water split, Ecart probable E_p and inlet pressure drop. It is shown that when vortex finder diameter or shape varies, a compromised optimum performance can be identified, resulting in relatively small inlet pressure drop, E_p, and water split. Both d₅₀ and E_p are more sensitive to feed solids concentration than inlet pressure drop and water split. Overall, the effect of vortex finder length on the separation efficiency of particles is much less significant than diameter and shape, which shows opposite trends at low and high feed solids concentrations. All these results can be well explained using the predicted tangential and axial velocities and solid volume fraction.