Rheology for deposition control and deposit failure risk analysis

Abstract

Application of rheology to the post-deposition behaviour of tailings is important for the design of the slope of the impoundment, control of layering for purposes of strength enhancement through desiccation, properly describing the mixing of different tailings streams and for dam breach consequence analysis. This paper aims to advance the understanding of tailings rheology in the post-deposition context to aid all of these applications. Firstly, thixotropy and its quantitative implications for beach slope and layer geometry are explored using a simple treatment. Secondly, method dependency in yield stress measurement is discussed, along with how such uncertainty can be practically handled by considering the appropriate stress path and timescale for a particular application. Finally, numerical simulation using a thixotropic rheology of channel flow down a beach and runout from a dam breach experiment, conducted in a centrifuge, is used to highlight the utility of advanced rheology to such problems. The paper uses data collected from published work on both hard rock and oil sands tailings over the last 15 years.