Pore structure characterization and seepage analysis of ionic rare earth orebodies based on computed tomography images

Pore network structure of ore body is a diffusion channel of leaching agent solution that exerts a significant influence on seepage. The ore body structure, pore distribution, pore and throat size, and pore network characteristics of topsoil, weathered, and semiweathered layers of ionic rare earth ore in southern Jiangxi Province were explored in this study. The effect of leaching operation on the pore structure was investigated, and main factors affecting the seepage were analyzed. Results showed that the semiweathered layer presents a dense structure and a small number of unconnected pores. Pores of topsoil and weathered layers are mainly long and narrow column openings with some planar fractures. Even pore distribution and large size span were observed. Compared with the weathered layer, the topsoil layer demonstrates larger voids, smaller average pore volume and equivalent radius, and fewer coordination throats; however, the average equivalent radius of the throat in the topsoil layer is larger and large-scale channels exist through ore body vertically. Hence, permeability of the topsoil layer is significantly higher than that of the weathered layer. Colloidal clay minerals migrate easily and the occurrence of silting in the small porosity blocks the throat and significantly decreases the permeability of the ore body in the leaching process. The equivalent radius of the throat is the key to the seepage. Reducing the migration of fine particles is an effective measure to protect the throat and shorten the leaching period.