Stochastic beach profile modelling

Abstract

Modelling of a tailings beach using a time series of thickener output (flow rate and solids concentration) was first reported by Fitton et al. (2007). Seddon and Fitton (2011) presented statistical data on the performance of thickeners, and showed that the observed concave shape in tailings beaches could be adequately explained by this variability. They then proposed a stochastic method for the generalised modelling of tailings beaches. The aim of this paper is to demonstrate the application and results obtained by the use of this method. This paper shows how thickener performance statistics in the form of frequency functions for variations in (a) underflow solids concentration; and (b) mass flow rate, can be combined with a set of rheology results to develop a predictive beach slope distribution. Data developed from this distribution are then used as an input to a deposition modelling program. The developed beach profile is presented for a typical case.

Stochastic modelling of beach profiles including the influence of thickener performance

“…As noted above, the commonly available data on thickener performance are solids concentration and mass flux. For the purposes of beach slope prediction, it is necessary to convert these values to representative rheological parameters and volumetric flux (Seddon et al 2015). The methodology adopted in this paper to predict beach profiles is a replication of that set out in Seddon et al (2015).…”

“…In this paper (as in Seddon et al 2015), beach slope predictions have been carried out using the method of Pirouz et al (2014), although other equivalent methods could be used.…”

“…For the variability of underflow solids concentration, Seddon and Fitton (2011) reported values of CV in the range of 0.025-0.08. Seddon et al (2015) adopted a value of 0.05 in their reported analysis. Incorporation of the additional thickener data (Pirouz et al 2017) has not changed this assessment, which is still considered to be a reasonable estimate for a well operated thickener.…”

“…For characterisation of mass flow rate, Seddon and Fitton (2011) reported values of CV in the range of 0.12-0.19, noting that this was based on the use of a symmetrical distribution. Seddon et al (2015) adopted an asymmetrical distribution using CV = 0.07 for the top, and CV = 0.12 for the bottom of the range. This is still considered to be representative of 'good' thickener operations (Pirouz et al 2017).…”

“…Data demonstrating that the variable throughput of thickeners can be characterised on a statistical basis was also presented. Seddon et al (2015) then presented a more rigorous design methodology utilising a stochastic approach to predict beach slope as a time series, and to model the subsequent build-up of the beach using a short time step increment as input into a tailings deposition type program.…”