Study on Flow Behaviour in the Short-Throat-Jet Type Flotation Machine

A two-dimensional model of the short-throat-jet flotation machine was developed for studying the flow behaviour and some difficult to measure parameters in the device using computational fluid dynamics (CFD). A laboratorial model was established for verifying the dependability of CFD, while a good agreement between measurement results and simulation was presented. With the inlet pressure set as 0.015 MPa, the minimum pressure close to the wall of the inhale section was obtained as 1200 Pa at Y = 164.2 mm, which was the optimal position for inhaling air. Moreover, the maximum pressure at the cell bottom was about 44,600 Pa at X = 15 mm from the centre of the jet, which was useful in selecting a suitable material to build the cell bottom. Analysis of wall shear stress showed that the wall shear stress on the right side of the jet was larger than that on the left side. Closer to the jet nozzle, the shear stress was larger. The wall shear stress on the right side of the short throat was likewise found to be larger than that on the left side, maximum difference being 140 Pa at Y = 115.5 mm. Analysis of the velocity field showed that the velocity decreased by 50% from the inlet to the outlet of the throat, and seven obvious vortexes were found to exist in the cell, where two of them in the inhale section were advantageous for inhaling air.