Volume change behaviour of mixtures of coarse coal reject and tailings

Abstract

Co-disposal of fine-grained wastes or tailings and coarse-grained wastes or coarse reject generated on the processing of the run-of-mine coal, offers potential economic, geotechnical and environmental advantages over conventional separate disposal practices. To evaluate the compressibility behaviour and performance of coarse reject, tailings and mixtures of coarse reject and tailings, laboratory compression testing was performed in a large, purpose-built consolidometer on scalped clay mineralrich coarse reject, on tailings slurry, and on combined scalped coarse reject and tailings at two dry mass ratios of 6:1 and 3:1 (coarse reject to tailings). In this paper, the results of the compression testing on the specimens are compared and the settling and compressibility behaviour of the tailings slurry, effect of mixture ratio and scalping on the permeability and compressibility of the mixtures are discussed. The results of this investigation can assist in coal washery waste management, through the improved understanding of the geotechnical behaviour of codisposed coal washery wastes.