Abstract
The objective of this work was to measure the coefficient of restitution of fine granite sand dust (passing sieve ASTM N°30) and to study its influence on the prediction of classification parameters in an elutriator device. Three types of restitution coefficients were evaluated in the computational fluid dynamic model: experimental, elastic, and half the experimental value. The influence of process variables, such as the inclination angle of the equipment and the air inlet velocity, on the efficiency of the obtained fine and coarse fractions was also studied. The results indicate that the coefficient of restitution significantly influences the efficiency parameters calculated for the inclined tests, given the greater contact that exists between the particles and the equipment wall. The experimental value of the coefficient achieved almost total congruence with the coarse fraction collected for the tested velocities. For the vertical tests, the variation of the coefficient did not show significant differences for both collected fractions. The results obtained in this work allowed to gain a deeper insight into the studied gas-solid systems, and to improve the numerical predictions on fine particles classification processes widely used in the ceramic, mining and metallurgical industries.
Highlights
Elutriators are gas-solid separation equipment consisting of one or more vertical tubes, through which a stream of gas contaminated with dust flows upward
The objective of this work is to measure the coefficient of restitution (CoR) of small and irregular granite sand powder and analyze its influence on the separation efficiency of an elutriator, comparing experimental and numerical results
It is observed that the coefficient of restitution does not have a great influence on the results, this is because the particles do not interact with the wall to a great extent in the vertical elutriator position (0° of inclination)
Summary
Elutriators are gas-solid separation equipment consisting of one or more vertical tubes, through which a stream of gas contaminated with dust flows upward. With terminal settling velocities greater than the upward flow rate of the gas, are separated and collected at the bottom of the device. The coefficient of restitution is a measure of the energy dissipation between two colliding bodies. It is 0 for perfectly plastic collisions and 1 for perfectly elastic collisions. Several studies demonstrate the improvements in the computational fluid dynamics predictions (CFD-DEM) by adjusting the drag coefficient of the particles in the separation processes [2,3]. Few works report the experimental measurement of the coefficient of restitution for small and irregular particles and its application in improvements to CFD simulations [4,5]
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