Non-invasive particle-scale investigation of the effects of blade speed and particle properties on mixture homogeneity evolution using X-ray CT

Abstract

A binary system of particles was mixed in a vertically bladed mixer and mixture homogeneity wasreported usingX-ray computed tomography (CT) and a particle-scale mixing index. The effects of particledensity, size, and volume fraction,as well as mixer blade speedonmixture homogeneity evolution were investigated.For same sized particles, mixture homogeneity was found todeteriorate with increasingdifference in particle densities. However, this could be countered by controlling for percolation, e.g., mixing heavier particles of larger size with smaller/lighter particles to improve mixing. Increasing blade speeds from 10 rpm to 30 rpm,deteriorated mixing,however, furtherincreases from 30 rpm to 60 rpm resulted in improvements, indicating possible flow regime changes at different rotational speeds. Increases in the volume fraction oflarge/light particles increased the penetration of these particles to the bottom layers dueto overall flowchanges,which in turnappeared to improve mixing.