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Abstract

Thickening is a pivotal process in the mining industry, representing a cost-effective technology for water recovery from tailings streams. Enhanced thickener performance results in substantial energy savings and augments water recovery proximal to the milling site. The rheological properties of slurry at the raking zone significantly influence thickener performance. The dynamics of high-density slurries at the thickener's bottom floor are crucial to thickener operation and the tailing transport system. Furthermore, the flowability of highly viscous material is paramount for pumping the thickener underflow. An open channel was developed for non-Newtonian tailing samples to comprehend the behaviour of dense slurry along the path to a thickener floor. This study presents an experimental investigation of gravity driven flow in a custom open channel flume designed to replicate the sliding zone of industrial thickeners. Three tailings materials from copper and gold operations were characterised using particle size analysis, vane rheometry, and automated mini slump testing. Open channel tests conducted over controlled slopes and rheological conditions yielded measurements of sliding velocity and deposited bed depth. Across all tests, the three tailings showed differences in their movement in the channel. Copper Tailings (CT-02) consistently flowed the fastest, while Copper Tailings (CT-01) remained in the middle range. Gold Tailings (GT-01), which had the highest solids content and finest particle network, moved more slowly and left noticeably thicker beds along the flume. These differences reflect how yield stress and particle size influence both the surface flow and the material that remains deposited after each run. By comparing the vane measured yield stress with the apparent yield stress from cylindrical slump tests, the study also evaluates the limitations of each method for characterising dense tailings. While both approaches are consistent at moderate yield stresses, divergence at higher concentrations underscores the importance of selecting measurement techniques appropriate to the material’s rheological range. The results give practical, measured evidence of how high-yield-stress tailings slide and deposit in an inclined channel, which helps explain the behaviour observed on thickener floors.