Geotechnical characterisation of coal tailings down the beach and constant rate of loading consolidation in a slurry consolidometer

ABSTRACT The conventional disposal of slurried tailings in a tailings storage facility (TSF) leads to the formation of a beach, on which the tailings sort hydraulically, settle, consolidate, and desiccate upon exposure. Basic geotechnical testing, such as specific gravity, Atterberg limits, and particle size distribution, found that there was no particular trend of changes in the tailings properties down the beach. The settled sediment found in a settling test was slurry-like and unsuitable for conventional oedometer testing. Constant rate of loading (CRL) consolidation testing is more representative of the continuous disposal of tailings slurry than conventional step loading. Consolidation testing in a slurry consolidometer was conducted and captured from a slurry-like to soil-like state. A slow rate of loading increased the test time, while a too quick rate of loading built up very high excess PWP. The test results showed different stages of consolidation, depending on excess PWP development and dissipation, and applied stress.