Developing a methodology for characterising in-situ viscosity profiles in tumbling mills
type: CreativeWork
description: Milling is the most expensive operation in a mineral processing circuit and accounts for the highest amount of energy utilized. The efficiency of the milling process is affected by the rate of breakage of bigger rocks and the rate of transport of the slurry within and out of the mill. The transport of material in the mill is dependent on the rheological properties of the slurry such as viscosity. Viscosity is therefore one of the important parameters that influences the transport of the material in the mill. Slurries in tumbling mills are known to exhibit non-Newtonian behaviour. This means slurry viscosity is not constant but is a function of shear rate. To characterize slurry transport in the mill it is necessary to study the viscosity distributions in order to determine regions of high and low resistance to flow in the mill. To determine the influence of slurry viscosity on the transport of particles it is important to quantify the typical shear rate ranges that occur inside the tumbling mill. The aim of this project w as to develop a methodology for characterising viscosity distributions inside a tumbling mill using in-situ shear rate distributions obtained from PEPT at different solids concentrations and mill speeds. The P EPT technique was used to study the in-situ mot ion of slurry particles with in tumbling mill charge using a single radioactive tracer. Rheology experiments were conducted using a U-tube rheometer. The rheometer experiments were performed to characterise the rheological behaviour of the El Soldado slurry at a wide range of shear rates. The PEPT results provided information about the typical shear rate ranges that occur inside the mill. The combination of these results enabled the quantification of viscosity distribution from the slope of the rheogram at typical shear rates found in the tumbling mill. The rheology results indicated that the Bingham model is the rheological model which gives the best description of the rheology of El Sol dado s…
abstract: Milling is the most expensive operation in a mineral processing circuit and accounts for the highest amount of energy utilized. The efficiency of the milling process is affected by the rate of breakage of bigger rocks and the rate of transport of the slurry within and out of the mill. The transport of material in the mill is dependent on the rheological properties of the slurry such as viscosity. Viscosity is therefore one of the important parameters that influences the transport of the material in the mill. Slurries in tumbling mills are known to exhibit non-Newtonian behaviour. This means slurry viscosity is not constant but is a function of shear rate. To characterize slurry transport in the mill it is necessary to study the viscosity distributions in order to determine regions of high and low resistance to flow in the mill. To determine the influence of slurry viscosity on the transport of particles it is important to quantify the typical shear rate ranges that occur inside the tumbling mill. The aim of this project w as to develop a methodology for characterising viscosity distributions inside a tumbling mill using in-situ shear rate distributions obtained from PEPT at different solids concentrations and mill speeds. The P EPT technique was used to study the in-situ mot ion of slurry particles with in tumbling mill charge using a single radioactive tracer. Rheology experiments were conducted using a U-tube rheometer. The rheometer experiments were performed to characterise the rheological behaviour of the El Soldado slurry at a wide range of shear rates. The PEPT results provided information about the typical shear rate ranges that occur inside the mill. The combination of these results enabled the quantification of viscosity distribution from the slope of the rheogram at typical shear rates found in the tumbling mill. The rheology results indicated that the Bingham model is the rheological model which gives the best description of the rheology of El Sol dado s…
author: Mangesana, Nobathembu
language: eng
date published: 2012
date modified: 2026-07-22T22:22:44Z
provider: University of Cape Town
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Department of Chemical Engineering

PropertyValue
property ID: Handle
value: http://hdl.handle.net/11427/16917