Segregation phenomena in gravity separators: A combined numerical and experimental study
Artikel i vetenskaplig tidskrift, 2016
In this paper we formulate a computational framework for characterizing and optimizing the performance of a
destoner, an example of a density-based separation technique. The numerical framework combines Computational
Fluid Dynamics (CFD) simulations with a Discrete Element Method (DEM), implemented in an opensource
computation package (OpenFOAM). This framework is validated first by comparing the simulations
with experiments for a standardized test case and further with our experimental study of a pilot-scale destoner.
We evaluate the combined effects of process conditions, such as separator deck inclination, vibration speed and
fluidization velocities on destoner performance. Our simulations showhowthe heavy product fraction in the discards
streamincreases over timewith a corresponding accumulation of the ‘valuable’ light product at the base of
the deck, indicating segregation between the stones (heavy product) and the grains (light product).We also find
that these separation profiles are highly sensitive to changes in deck surface air velocities, with the gradual development
of segregation zones at velocities close to the minimum fluidization velocity of the heavier component.
Optimal separation is seen at a deck inclination of 4° and a fluidization velocity of between 1.75 and
2 m/s. Our simulation results also agree well with the experimental findings indicating the usability of the proposed
framework for the design and optimization of gravity separators.
Design and optimization