Abstract:To improve the rare earth leaching efficiency of the heap leaching process, the influence of particle gradation combination type on the seepage characteristics of the weathered crust elution-deposited type rare earth ore was explored using layered graded column leaching experiment, CT scanning and image processing technology. The combination type of layered graded ore samples was optimized, and the seepage mechanism of layered graded ore samples was revealed from the perspective of microscopic pore structure. The results show that the permeability coefficient of the combined ore samples is higher than that of the raw ore, and the permeability coefficient of the coarse, medium and fine ore samples is the largest. The pore volume of raw ore is concentrated in -0.001 mm3, while the coarse, medium and fine particle size layers of coarse, medium and fine ore samples are mainly distributed in +0.001 mm3, 0.0001 mm3-0.001 mm3, -0.0001 mm3. The pore length and width of the raw ore are less than 0.4 mm, while the pore lengths of the coarse, medium and fine-grained layers are 0.4 mm-1 mm, 0.2 mm-0.4 mm and -0.2 mm respectively, and the pore widths are 0.4 mm-1 mm, -0.3 mm and -0.2 mm respectively. The pore throat length of the raw ore is mainly distributed with 0.1 mm-0.3 mm, while the coarse, medium and fine-grained layers are concentrated in 0.1 mm-0.3 mm, 0.2 mm-0.4 mm, and 0.2 mm-0.5 mm. The overall connectivity of coarse, medium and fine ore samples after leaching is better than that of raw ore. The research results can provide a theoretical basis for improving the rare earth leaching efficiency of the heap leaching process of weathered crust elution-deposited rare earth ore.