Rheological properties and wall-slip behavior of cemented tailing-waste rock backfill (CTWB) paste

Cemented tailing-waste rock backfill (CTWB) can effectively improve the ecological environment of the mine. CTWB paste exhibits unique rheological and wall slip characteristics during pipeline transport, which has a significant impact on reducing transport resistance and extending transport distance. A numerical model that integrates material ratio and wall-slip was established by analyzing the rheological test results. COMSOL Multiphysics was used to numerically simulate the paste flow process and output the flow parameters distribution. The results show that CTWB is a yield-plastic fluid, and the shear-thickening phenomenon occurs at 67% and 69% solids content, respectively, and the critical shear rate value gradually increases with the SC. Increasing the coarse aggregate content significantly improves the paste fluidity, and the rheological parameters (plastic viscosity and yield stress) decrease linearly with coarse aggregate content. CTWB paste flow structure has an "equilibrium distance" at which slip velocity starts to stabilize. Tailing-waste rock (T/W) ratio, inlet velocity (IV), and solid content (SC) have a significant effect on the CTWB paste slip behavior. Slip contribution ratio (SR) tends to increase and then decrease with IV, and the process can be described by a quadratic function. Although the SR decreases gradually with the T/W ratio, it can be inferred that the optimal transportation effect is achieved at the T/W ratio is 5:5.