A. G. McLean

Document Type

Conference Paper

Publication Date


Publication Details

This conference paper was originally published as McLean, AG, Fine coal dewatering by compaction in bins exhibiting reliable discharge, in Aziz, N (ed), Coal 1998: Coal Operators' Conference, University of Wollongong & the Australasian Institute of Mining and Metallurgy, 1998, 405-414.


This paper firstly reviews the requirements for container and hopper design for reliable discharge. Discussion is then directedt o the evaluationo f the consolidations tressesa cting in both in both the cylinder and hopper sectionsd uring both initial and flow conditions. Here the vast difference, especially in vicinity of the bin outlet, between the initial or filling and flow conditions is highlighted. This vast difference has major design and operation implications. A further major implication is that all bulk solids must dilate to flow. The opportunity to simultaneously attain reliable discharge and partial moisture removal is also examined. The selection of design parameters to maximise the consolidation stresses in both the cylindrical and hopper sections is detailed. In regard to the latter, it is recommended fine coal bins be discharged using low friction lined transition hoppers with large outlet spans. Such outlets will discharge fine coal in a relatively compacted state. This compaction state should exhibit minimum water retention and short term moisture uptake. The multiphase attributes of fiDe damp coal flow is then considered. Here is it noted, as a consequence of the dilation in the hopper negative or suction interstitial fluid pressures form. It is noted such pressures generate an adverse pressure gradient which significantly retards the discharge. One technique to conveniently eliminate the adverse pressure gradient is to install low pressure high volume air sparging to the hopper. It is suggested this air sparging will have the added benefit of effecting partial moisture reduction. This technique should prove far more reliable than post feeder compaction using relatively complex mechanical systems.