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Abstract
Dense medium cyclone (DMC) units have been extensively used to upgrade run-of-mine coal in the contemporary coal preparation industry. In the past decades, development of DMCs has been mostly based on empirical methods, however, this would not give rise to the much enhanced understanding of the fundamentals of DMC under diverse conditions, and the consequences often have limited applicability. Recently, mathematical modeling was used to improve the understanding of DMCs (Suasnabar and Fletcher, 1999 ; Brennan, 2003 ; Narasimha et al., 2006). Specially, Wang (2009) and Chu (2010) carried out systemically numerical studies on the multiphase flow of DMC by use of computational fluid dynamics (CFD) and discrete element method (DEM).
In this work, a statistic method, i.e., nonlinear curve fitting and multiple-regression procedure are repeated to analyse the CFD and CFD-DEM simulation data generated at the University of New South Wales, resulting in a set of empirical equations in which the performance of the DMC is a function of the geometrical, material and operational conditions. By use of the obtained equations, a robust and readily usable PC-based simulator of dense medium cyclone is developed to examine the performance of DMCs in a fast and easy way. The proposed computer model can investigate the effects of key variables related to the operational conditions, geometry and material properties on DMC flow and performance. In order to validate this computer model, comparisons of the effect of some key variables between the formulated empirical model and experimental results have been carried out.
Qualitative agreements between predicted results with those measured are obtained in various aspects, such as the effect of some key variables on the performance of DMCs, and already established trends in literature. Moreover, it is shown that the developed computer model can quantitatively predict the operation of DMCs, and is superior to other empirical models reported in the literature in terms of simplicity, generality and accuracy.
A comprehensive parametric study is carried out by use of the PC-based simulator, which explores the effects related to geometrical conditions, operational conditions and material properties on DMC flow and performance. The obtained relationship among the key variables could be used to facilitate engineering application and as a guide in the control, design and optimization of DMC units in coal preparation industry.