Analysis of the slump test for on-site yield stress measurement of mineral suspensions

The slump test, originally used to determine the 'workability' of fresh concrete, has since been adapted for use in the minerals industry. The slump test finds extensive industrial application for monitoring material consistency in tailings disposal operations. The parameter used as the indicator of consistency is the slump height, an empirical value, which is only relevant for the specific material being tested. We propose that the yield stress, a unique material property, is a better measure of consistency. Models relating the slump height to yield stress have been developed for the cone [Materiaux et Constructions (Paris) 17 (1984) 117; Christensen, G., 1991. Modelling the flow of fresh concrete: the slump test. PhD thesis, Princeton University; Canadian Geotechnical Journal 28 (1991) 457; Journal of Rheology 42 (1998) 865] and cylinder [Journal of Rheology 40 (1996) 1179] slump tests. In this investigation, a direct comparison of the cone and cylinder models for yield stress measurement of mineral suspensions is undertaken. The analysis clearly shows that the cylinder model more accurately predicts the material yield stress. A strong case is made for the replacement of the widely used cone test with the simpler, cheaper and more accurate cylinder test. (C) 2003 Elsevier Science B.V. All rights reserved.