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Minerals 2015, 5(2), 164-188; doi:10.3390/min5020164

Numerical Simulations of Two-Phase Flow in a Self-Aerated Flotation Machine and Kinetics Modeling

1
Numerical Porous Media Center, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
2
Department of Engineering Science and Mechanics, Virginia Tech, Blacksburg, VA 24061, USA
*
Author to whom correspondence should be addressed.
Academic Editors: Michael G. Nelson and Dariusz Lelinski
Received: 14 December 2014 / Revised: 11 March 2015 / Accepted: 19 March 2015 / Published: 30 March 2015
(This article belongs to the Special Issue Flotation Technologies for the Future)
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Abstract

A new boundary condition treatment has been devised for two-phase flow numerical simulations in a self-aerated minerals flotation machine and applied to a Wemco 0.8 m3 pilot cell. Airflow rate is not specified a priori but is predicted by the simulations as well as power consumption. Time-dependent simulations of two-phase flow in flotation machines are essential to understanding flow behavior and physics in self-aerated machines such as the Wemco machines. In this paper, simulations have been conducted for three different uniform bubble sizes (db = 0.5, 0.7 and 1.0 mm) to study the effects of bubble size on air holdup and hydrodynamics in Wemco pilot cells. Moreover, a computational fluid dynamics (CFD)-based flotation model has been developed to predict the pulp recovery rate of minerals from a flotation cell for different bubble sizes, different particle sizes and particle size distribution. The model uses a first-order rate equation, where models for probabilities of collision, adhesion and stabilization and collisions frequency estimated by Zaitchik-2010 model are used for the calculation of rate constant. Spatial distributions of dissipation rate and air volume fraction (also called void fraction) determined by the two-phase simulations are the input for the flotation kinetics model. The average pulp recovery rate has been calculated locally for different uniform bubble and particle diameters. The CFD-based flotation kinetics model is also used to predict pulp recovery rate in the presence of particle size distribution. Particle number density pdf and the data generated for single particle size are used to compute the recovery rate for a specific mean particle diameter. Our computational model gives a figure of merit for the recovery rate of a flotation machine, and as such can be used to assess incremental design improvements as well as design of new machines. View Full-Text
Keywords: minerals flotation machines; two phase flows; flotation kinetics; rate constant; particles size distribution minerals flotation machines; two phase flows; flotation kinetics; rate constant; particles size distribution
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Fayed, H.; Ragab, S. Numerical Simulations of Two-Phase Flow in a Self-Aerated Flotation Machine and Kinetics Modeling. Minerals 2015, 5, 164-188.

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