Evaluation of a non-Newtonian two-layer model for high concentration suspensions

High concentration thickened tailings slurries that appear to be homogeneous mixtures often contain coarse particles that settle in the pipeline under laminar flow conditions. During pipeline transport, these coarse particles may eventually settle to the pipe invert. Frequently, these high concentration suspensions are misclassified as homogeneous slurries, leading to the use of incorrect models for predicting the pressure gradient and flow behaviour. This paper discusses the use of a non-Newtonian two-layer model to predict the pressure gradient of a high concentration suspension with a sliding bed in laminar flow conditions. The success of the model is measured by comparing the results obtained by applying the model to experimental results for a typical iron ore tailings slurry. It was found that the model predicted the laminar flow pressure gradient with less than 10% error for slurries with carrier fluid yield stresses above 10 Pa.