Abstract

Cemented paste backfill (CPB) technology has the advantages of safety, environmental friendliness, economics, and efficiency. This method offers assurances for practical underground mining and tailings pond management. The bed drainage channel structure and coarse particles with diameters above 45 & mu;m were reconstructed and quantitatively characterized in 3D by computed tomography (CT) for the whole tailings thickening process. The spherical pore diameter evolution trends, stick throat channel radius and throat channel length were analyzed with and without shear using the pore network model (PNM). The functional relationship between the average spherical pore diameter and bed pressure is given, and the boundary values between the bed' primary and secondary drainage channels are clarified. The ratio of throat length to diameter (Tw) is proposed to measure the difficulty of throat channel structure on the water discharge in the bed. The effects of the volume and number of coarse particles with diameters above 45 & mu;m on the bed porosity and pore connectivity were analyzed. The range of particle diameters that significantly affect the bed porosity and pore connectivity was clarified. The results show that the spherical pore diameter, throat channel radius, and throat channel length decrease with increasing bed pressure with and without shear. Moreover, the average spherical pore diameter in the bed has a power-law relationship with the bed pressure. The spherical pore diameter, throat channel radius, and throat channel length with shear were lower than without shear, and the slurry concentration was higher than without shear. The main drainage channels of the bed with and without shear consisted of large pore structures with diameters of not less than 433.3 & mu;m and 329.8 & mu;m, respectively. The throat channel structure parameter Tw increases with the increase of bed pressure. When Tw is higher than 8.7, the discharge of water in the bed is hindered, making it challenging to improve the slurry concentration. The porosity and pore connectivity of the bed decreases with increasing volume and number of coarse particles. Among them, coarse particles in the diameter 150-300 & mu;m range significantly reduce the bed porosity and pore connectivity. This study guides the preparation of high-concentration paste filling slurry, which is helpful to improve the efficient mining capacity of mines and have fewer tailings ponds.