Effects of Ore Particle Size Distribution on Rare Earth Leaching Process of Weathered Crust Elution-Deposited Rare Earth Ores

This paper investigates the rare earth (RE) leaching process of weathered crust leached rare earth ores (WCE-DREOs) with different ore particle sizes. Ore particles were categorized into seven distinct size ranges: −0.106 mm, +0.106 mm to −0.15 mm, +0.15 mm to −0.25 mm, +0.25 mm to −0.85 mm and +0.85 mm. The study examined the correlation between the thickness of the electrical double layer (EDL) and the RE content, as well as the swelling ratio of clay minerals. The findings demonstrated that the order of RE content with respect to varying particle sizes was as follows: C−0.106>C+0.106~−0.15>C+0.15~−0.25>C+0.25~−0.85>C+0.85 (C represents RE content). The RE content of full particle size was found to be 7.93 mg/g, with the particle size −0.106 mm exhibiting the highest RE content of 2.02 mg/g. In the fitting of the relationship between the RE content and the thickness of the EDL, it was observed that the particle size −0.106 mm exhibited a consistent correlation with the Logistic function y=2.03−0.43/(1+1.49x172.39). In the study of the swelling performance of the WCE-DREOs, the order of the swelling ratio of ore samples in different particle sizes was δ−0.106>δ+0.106~−0.15>δ+0.15~−0.25>δ+0.25~−0.85>δ+0.85(δ represents the swelling ratio), and the swelling ratio was 3.34%, 2.92%, 2.33%, 1.55% and 0.01%, respectively. In the fitting of the relationship between the swelling ratio of clay minerals and the thickness of the EDL, it was observed that a particle size of −0.106 mm corresponded to the exponential function y=3.65−99.89·exp⁡−x/0.12. The results of the study provide useful assistance in the mining of the WCE-DREOs.