Jiapeng Zhang, Dengjie Yan, Muwen Chen, Baoqiang Xu, Bin Yang, Bingyi Song, Lingxin Kong
ABSTRACT To address palladium scarcity and the low efficiency of conventional recovery processes, this work presents a molten–salt extraction strategy for palladium recovery via the CaPd 2 intermetallic compound. The process is based on the formation of CaPd 2 and its subsequent oxidation by active iodine species generated in molten CaI 2 . First–principles calculations reveal a charge transfer of approximately 0.84 |e| from Ca to Pd in CaPd 2 , resulting in an ionic bonding framework with covalent contributions arising from Ca–Pd orbital hybridization. This unique bonding characteristic confers excellent thermal stability, with a mass loss of less than 0.13% up to 1273 K. The CaPd 2 intermetallic compound was successfully synthesized and experimentally verified by X–ray diffraction and thermogravimetric analysis. In molten CaI 2 , iodine species selectively oxidize the anionic Pd species in CaPd 2 , enabling the direct recovery of metallic Pd. Under optimized conditions (1073 K, 1 h), palladium with a purity of 99.5 ± 0.3 wt.% was obtained. Unlike conventional pyrometallurgical and hydrometallurgical processes, the proposed approach eliminates the acid–leaching step and achieves rapid Pd recovery within 1 h. The results establish an iodine–mediated molten–salt recovery mechanism and provide a potential route for future palladium recovery from secondary resources.