MEASURING THE RHEOLOGY OF SLURRIES USING AN ONLINE VISCOMETER

Slurry rheology is an important property in many mineral processing sy stems, but its influence is not well understood and it is rarely incor porated into process design, analysis or optimisation. One reason for this is the difficulty of measuring rheology (particularly in plants) and of interpreting the output of such measurements. This paper presen ts a new procedure for obtaining a full shear rate-shear stress flow c urve for unstable slurries using the single bobbin Debex on-line visco meter. It is based on the use of a calibration algorithm which incorpo rates a correction for turbulent flow in the measurement vessel. It is shown that torque coefficient data from a variety of Newtonian fluids and non-Newtonian slurries fall on a single curve, and it is suggeste d that this calibration curve (the ''TC curve'') is characteristic for a particular instrument configuration. In principle, it can be easily determined using Newtonian fluids alone. It is shown that the Debex o n-line viscometer gives flow curves very similar to a conventional lab oratory viscometer when this procedure is applied.