Slurry Flow Modelling: A Critical Review of Deposition Velocity Correlations and Coefficient of Sliding Friction Measurements
Creators: Patel, Sonalika Rakesh
Publisher: name: University of Alberta Library
Year: 2024

<p>Settling slurry flows are widely encountered in the mining and mineral processing industries. Predictive models and correlations are used to estimate important pipeline parameters such as the frictional pressure loss and the minimum operating velocity (deposition velocity) required to prevent the formation of a stationary bed of particles in the pipe. An estimation of these parameters is required for slurry pipeline design. The accuracy of the estimated parameters depends upon the choice of the model and the quality of input parameters to the model. This research provides an evaluation of the existing deposition velocity correlations published in the literature to identify the most accurate correlations. Additionally, an experimental technique to measure the coefficient of sliding friction between particles and the pipe wall in settling slurry flows is introduced.<br>
The thesis presents a critical review of published correlations developed to predict the deposition velocity (VC). More than 60 correlations have been proposed by different researchers since 1950 to predict the deposition velocity, defined as the minimum operating velocity required to prevent a stationary deposit of particles from forming at the bottom of a pipeline. However, discrepancies among the predictions are significant, which limits the utility of many of the correlations. This review is an attempt to provide a comprehensive evaluation of these correlations based on their predictive performance, conceptual basis, and their applicability in different slurry flow conditions.<br>
The published correlations were categorized into different groups for an organized and efficient comparison. A sequential approach was used to eliminate the less accurate and more unreliable correlations. The results from the review indicate that no single correlation is universally applicable for all types of settling slurries and pipeline conditions. The Thomas (1979) correlation, Sanders et al. (2004), and Wilson (1979) were found to be reliable for fine and intermediate-sized particles. For slurries containing intermediate to coarse-sized particles, the SRC Correlation (Spelay et al., 2016) was recommended as the most suitable.<br>
Further improvements to these correlations could be achieved by developing a larger and more comprehensive experimental database, which would include data from larger pipe diameters and higher viscosity slurries.<br>
The second part of the thesis describes an offline technique to measure the coefficient of sliding friction, ηS, an important input parameter to the Saskatchewan Research Council (SRC) Two-Layer model, also known as the SRC PipeFlow model. The novelty of this measurement is its simplicity and ability to make measurements in both dry and submerged conditions. The proposed measurement technique was used to create a database of dry and submerged ηS values for nine particles, each for three different pipe materials relevant to the mining industry.<br>
Analysis of the results showed that dry and submerged ηS values were similar for stainless steel, carbon steel, and High-Density Polyethylene (HDPE), although the values in the submerged environment were generally slightly lower. The influence of different parameters such as the normal force, sliding velocity, particle size, particle shape, the height of the water column, and surface roughness were studied. It was found that, for the range of normal weights, velocities, and heights of the water column tested, ηS remained fairly constant; however, with the increase in roughness and particle angularity, an increase in ηS was observed. An effect of particle size was also observed.<br>
Further research is necessary to develop a more sophisticated experimental method that can closely replicate the velocities and particle motion in a slurry pipeline. This will ensure more precise measurements of the coefficient of sliding friction that can further contribute towards the improvement of the existing version of the PipeFlow model.</p>