Experiments for Enhancing Tailings Slurry Drainage and Geotechnical Performance Using Nonsegregation Flocculation and Geotextile

Pumping tailings slurry into geotextile bags is a burgeoning method employed to build tailings dams with improved tailings management. Fine contents bring great challenges for tailings stability. In this article, nonsegregation flocculation was selected for fine tailings. Experiments were carried out in three campaigns: nonsegregation flocculation of tailings slurry to reduce fine content in supernatant (low turbidity); water drainage evaluation via filtration tests, plus the measurement of capillary suction time; and the study of geotechnical properties, including hydraulic conductivity and yield strength. From the results, it is demonstrated that the tailings slurry without flocculation showed apparent particle segregation and poor drainage performance compared to tailings with nonsegregation flocculation. The yield strength with nonsegregation tailings was enhanced by two times to initial values. Scanning electron microscopy image analysis was used to check the attachment status of solid particles on geotextile surfaces after being used for filtration tests. The mechanism of enhancing geotextile drainage revealed that increased permeability and reduced geotextile pore-plugging should account for the enhanced water drainage and tailings stability. A pattern of achieving optimal drainage strategy of geotextile bag was recommended for building a tailings dam, which is to use large-sized flocs plus geotextiles with large pore sizes (up to 0.6 mm).