DOI: 10.54287/gujsa.1981398 ISSN: 2147-9542

Relationship Between Post-Leaching Particle Shape Characteristics and Rare Earth Element Recovery from Pb-Zn Flotation Tailings

Tuğba Deniz Tombal, Burçin Kaymakoğlu
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This study investigates the relationship between post-leaching particle shape characteristics and the recovery of cerium (Ce), lanthanum (La), and neodymium (Nd) from Pb-Zn flotation tailings leached in H2SO4, HCl, and HNO3 media. Rather than evaluating particle morphology as a factor controlling leaching performance, the study examines the morphological characteristics of solid residues obtained after leaching under the optimum conditions determined for each acid system. Leaching experiments were evaluated under previously determined optimum conditions, and the main focus of the study was placed on the morphological response of the tailings particles rather than on leaching optimization itself. Microscopic images of the raw tailings and post-leaching residues were analyzed by ImageJ to quantify circularity, roundness, solidity, aspect ratio, and porosity. The results showed that leaching performance and post-leaching particle morphology were both strongly dependent on the acid medium. Among the tested systems, H2SO4 and HNO3 generally yielded higher recoveries than HCl. The highest Ce and Nd recoveries were obtained in H2SO4 medium (69.18% and 77.10%, respectively), whereas the highest La recovery was achieved in HNO3 medium (79.42%). Image-based analysis revealed that H2SO4 leaching caused the most pronounced morphological transformation, reflected by lower roundness together with increased porosity and altered particle geometry, indicating the formation of more irregular and porous residues. In contrast, HNO3 leaching produced a comparatively smoother and more compact residual morphology, despite yielding high recovery values, particularly for La. HCl showed an intermediate morphological response but lower overall recovery performance. The combined evaluation of leaching results and particle shape parameters demonstrated that particle morphology provides useful complementary information for interpreting acid leaching behavior. In particular, porosity alone was not sufficient to explain the recovery trends, whereas the combined interpretation of porosity, solidity, and aspect ratio offered a more meaningful description of the structural response of the tailings to acid attack. The findings indicate that the relationship between particle shape and REE recovery differs among the investigated optimum leaching systems and that image-based particle shape analysis can support the interpretation of hydrometallurgical performance in complex flotation tailings.

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