The micro-scale mechanism of tailings thickening processing from metal mines

Water-locking flocs formed by ultrafine tailings particles are detrimental to the thickener underflow concentration in the process of gravity thickening operation for paste preparation. The relationship between mesostructure and seepage characteristics of tail mortar is typically ignored in the investigation of deep dehydration stage. Shearing seepage test of unclassified tailings sedimentation bed is carried out with copper tailings, morphology and geometric distribution of micropores are analyzed via computed X-ray tomography technology, and shearing evolution of micropore structure and seepage channel are investigated to evaluate the dewatering performance of underflow slurry using a three-dimensional reconstruction approach. Results showed that porosity decreases significantly with the occurrence of shearing action. Connected pore ratio and the average radius of throat channel obtain a peak value of 0.79 and 31.38 μm, respectively, when the shearing act is adopted for 10 min. However, reverse seepage velocity and absolute permeability in bed decrease in various ranges after the shearing action. Meanwhile, the maximum flow rate reached 1.537 μm/s and absolute permeability increased by 14.16%. Shearing action changes the formation process and pore structure of the seepage channel. Isolated pores relate to the surrounding flocs to form branch channels, which then become the main seepage channel and create the dominant water seepage flow channel.