UBC Theses and Dissertations
Segregation and hindered settling behavior of mine tailings suspension Li, Yuan
In the field of mining engineering, the occurrence of sedimentation phenomenon is commonly observed in various applications such as tailings thickening, deposition of tailings slurry into tailings ponds, and the backfilling of tailings materials. Extensive research has been conducted on the sedimentation behavior of mud, sludge, or dredged materials, yielding a wealth of documented knowledge. However, when it comes to some fundamental aspects of the sedimentation process specifically associated with mine tailings, our understanding remains somewhat limited. This thesis is concerned with the segregation and hindered settling behaviors of copper tailings suspension. A theoretical study was first performed to analyze the segregation mechanism of non-flocculated coarse particles during the hindered settling process of a suspension. Through the force balance analysis on particles of different sizes, a concept of critical particle size was introduced to account for the segregation phenomenon of coarse particles. A size-dependent continuous segregation mode was presented to illustrate the segregation sequence of particles. Based on the theoretical analysis, an experimental program was designed, which includes the conventional batch settling tests and interruptive batch settling tests. The experimental results indicate that the initial and continuous segregation behaviors in hindered settling of the copper tailings suspension can be captured and explained by the segregation mechanism proposed. To comprehensively investigate the overall settling behavior of copper tailings suspensions under different solids content and PSD conditions, additional batch settling tests were performed on three distinct types of copper tailings suspensions, each with different initial solids contents. Different settling modes were illustrated through the solids content profile and a type of three-dimensional PSD curve plot, which are the result of the combined influence of solids content and PSD of the suspension. In hindered settling impacted by continuous segregation, the properties of the suspension within the settling zone underwent changes over time. As a result, a modification was conducted to Kynch's approach to incorporate the influence of continuous segregation into the settling modes described by Kynch. The modified approach enables a more accurate representation and characterization of the sedimentation process impacted by continuous segregation.
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