Abstract: Before the paste is pumped or self-flowed to the well， it must be fully stirred to keep it homogeneous， enhance pumpability and ensure filling strength. In order to study the effect of mixing process parameters on paste homogeneity， the rheological characteristics of the paste were explored firstly， and the slump experiments were carried out to measure the rheological parameters of the paste. Based on the rheological properties of the paste， the full tailing paste was regard as a wet particle group with strong viscosity， a paste discrete element model was established by using Hertz-Mindlin with JKR contact method to simulate the slump experiment. The experiment and simulation results were compared to check the model parameters. Based on the paste discrete element model， a two-axis screw conveyor numerical model was constructed to investigate the effect of different process parameters on the degree of paste mixing. The research shows that the filling rate affects the stirring effect， and the mixing effect is better when the filling rate is 0.6， and the optimal filling rate should be in the range of 0.5~0.7； the stirring speed can promote vigorous movement between particles， but the rotation speed too large will also reduce the mixing degree of the material and affect the homogeneity of the paste. When the mixing speed is 10 rpm and 30 rpm， the mixing degree of the slurry is better. Considering the discharge efficiency， 30 rpm is the optimal stirring speed of the conveyor.

Key words: unclassified tailings paste, discrete element method, paste stirring, homogeneity