Effect of lifter shape and configuration on material transport part I: In rotating drums

Abstract

This paper presents the steady-state transport behavior of rotating drums fitted with (i) conventional bar lifters, and (ii) forward- and reverse-spiralling square lifters, when monosize hematite was fed through these devices. The steady-state hold-up in the drum fitted with the forward-spiralling square lifters was less than that in the drum fitted with reverse-spiralling square lifters. However, the dimensionless RTDs for the drums were independent of the direction of spiralling of the lifters. Overall, the degree of mixing within the drum hold-up, as revealed by the magnitude of the axial dispersion coefficient of the RTDs, was greater for the drums fitted with square lifters than for the drum fitted with conventional bar lifters. Between the forward- and reverse-spiralling configurations, the former showed a relatively greater degree of mixing. RTDs are discussed in this paper in terms of single-parameter models and mechanistic explanations for the experimental observations are offered where appropriate.