Semester

Summer

Date of Graduation

2004

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Mining Engineering

Committee Chair

Felicia F. Peng.

Abstract

The objective of the present study was to improve the understanding of multiple phase flows in hindered-settling bed separators (HSBS). A better understanding of mineral separation in HSBS and the role of structured plates was gained through studies conducted with Computational Fluid Dynamics (CFD) analysis tools. An Euler-Lagrange model from CFD technique is used for this purpose.;In an Euler-Lagrange model, two dimensional incompressible Navier-Stokes equations are solved with the implementation of a finite volume approach over staggered grids with application of Baldwin-Lomax turbulent model. The overall accuracy of the method is second-order in both space and time. The calculation of the liquid field provides the liquid velocity profile in the separator. The integration of movement equations of the particles makes it possible to track the trajectories of discrete particles in the fluid field. The integration of individual particle behavior results in a description of macroscopic behaviors of particle assembly in the fluidized-bed and makes a prediction of density separation using statistical analysis of a number of representative particles. The operating parameters including suspension density set point value, fluidizing water velocity, feed pipe water velocity, feed solid concentration, particle sizes and column geometry were investigated. The simulation has been validated against in-plant test results. Comparisons between the simulations and experiments show the capability of this multiple phase model.;An Euler-Lagrange model has also been developed which simulates the role of structured plates in the HSBS. This device utilizes corrugated plates to improve the performance of conventional hindered-settling bed separators. An investigation utilizing the model was carried out and has predicted an improved separation performance denoted by lower probable errors, lowered processing size limits, and higher throughputs at acceptable separation efficiencies. The model has also predicted that the unfavorable impact of the feed rate fluctuations is reduced significantly by the innovative addition of structured plate design. Experimental results and animation from simulation have verified that the fluid rotation exists between the structured plates to enhance the density separation. Laboratory test results indicate that improvements in separation efficiency can be achieved using the addition of structured plates. The simulation also revealed that the baffled column with structured plates can hold a broader range of suspension densities in response to the fluctuation of solid feed rate than the open column. Finally, the pulsation flows in the presence of the structured plates are simulated. It was found there exists an optimal range for frequency and amplitude of pulsation to improve separation efficiency.

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