Abstract

The flocculation effect of tailings has an important influence on the turbidity of thickener overflow and the solidliquid separation effect of tailings slurry. However, pipeline flocculation has not been applied to the tailings dewatering in the thickening process of mines. Moreover, previous studies are limited by the size of the experimental device, and the variation of floc structure with settling height during the free settling process in the thickener was insufficient. Therefore, based on a plot thickener with sufficient height (113 cm) and the pipeline flocculation device, the evolution of the structure and physical properties of flocs with settling height can be clearly explored. And the effects of flocculant dosage, tailings slurry concentration, flocculant slurry concentration, and fluid shear gradient on floc structure, physical properties, and supernatant turbidity in pipeline flocculation were studied. The evolution of floc size and physical properties with settling height in thickener with or without shear was also analyzed. The results show that when the flocculant dosage is 90 g center dot t(-1)-105 g center dot t(-1), the concentration of tailings slurry is 20 wt% similar to 25 wt%, the concentration of flocculant solution is 0.005 wt% similar to 0.01 wt%, and the fluid shear gradient is 29.2 s(-1)-48.7 s(-1), the tailings particles are fully mixed with the flocculant solution. Which effectively reduces the turbidity of the overflow. The flocs were broken during the settling process. Accordingly, the floc size and settling velocity decreased with the decrease in settling height, and the density and strength of flocs increased with the decrease in settling height. The reasonable control of the shearing speed of the rake can improve the settling velocity of flocs, which is beneficial to the solid-liquid separation of thickening. Through the research of this study, a method of thickening and dewatering mine tailings slurry through pipeline flocculation was proposed. The variation law of floc structure in the process of free settling in thickener was explored, which provided a reference for the rapid solid-liquid separation of tailings slurry in the thickener.