A study on compressibility and permeability of tailings with different particle sizes under high pressure

Mine tailings are stored in tailings storage facilities (TSF), normally in the form of tailings dams. High-stacked tailings dams (HTD) are failure-prone for several reasons, such as overtopping, seepage failure, and strength deterioration. The investigation of compressibility and permeability of tailings material with different particle sizes under high pressure is essential for safety stability. By self-developed high-pressure consolidation permeability apparatus (HCPA), the laboratory conjoined consolidation permeability tests are carried out on tailings with different particle sizes at the maximum consolidation pressure (σ’_v) of 5 MPa. For compressibility of tailings in the high-pressure stage (σ’_v > 2 MPa), the void ratio e of tailings with different particle sizes has a new linear relationship with σ’_v. Coarse-grained tailings have a “secondary- compression-like property” due to particle breakage under high pressure. The hydraulic conductivity of tailings under high pressure presents a piecewise linear k-σ’_v relationship. With the decrease in particle size and the increase of σ’_v, the seepage pattern of tailings changes from channel seepage to micropore seepage. σ’_v = 2 MPa is regarded as the critical value for high-pressure compression of tailing, and the corresponding microscopic critical value of the average particle spacing is 1.2–1.8 nm. This research explored useful information on the compressibility and permeability of tailings with different particle sizes under high pressure that can provide a reference for improving the stabilization of HTD.