Blending with Silos

This paper deals with the mixing and blending of bulk materials by recycling the contents in a mass-flow silo. The limiting conditions for mass-flow are briefly reviewed, with the importance of this flow pattern type on the influence of the blending efficiency of a particular silo being highlighted. It is then shown how the analytical prediction of the flow patterns in a mass-flow silo allow the theoretical prediction of the blending capacity of a silo to be determined. Expanding the mass-flow silo concept to include the hopper-in-hopper insert developed by Johanson, it is shown how the application of this silo configuration allows for more efficient mixing and blending over the conventional mass-flow silo. Experimental data obtained from pilot scale test rigs is shown to corroborate the analytical predictions.