Immobilization of Pyroprocessing Molten Salt Waste with Aluminosilicate Ceramics

The waste molten salt (LiCl-KCl) generated from high-temperature pyrometallurgical processing of spent fuel has high water solubility and strong corrosiveness. Thus, it is difficult to be effectively solidified with traditional matrices, such as cement and glass. In this study, high-temperature solid-phase reactions were carried out between reactive aluminosilicate precursors and LiCl, KCl, LiCl-KCl, and their oxalate-transformed products (Li 2 C 2 O 4 -K 2 C 2 O 4 , NaCl) to synthesize ceramic waste forms containing Li + , K + , and Cl - . The phase composition, morphology, and elemental distribution of the solidified products were characterized using XRD, SEM/EDS, ICP, and ion chromatography. The results indicate that: (1) When directly solidifying LiCl-KCl, the solidification rates of Li + and K + were relatively high, while that of Cl - was comparatively low; (2) Using oxalate-transformed products (Li 2 C 2 O 4 -K 2 C 2 O 4 , NaCl) obtained by heating the simulated molten salt of LiCl-KCl mixed with oxalic acid as starting materials, the solidification rates of Li + , K + , and Cl - are significantly increased; (3) the leaching rates of Li + , K + , Na + , and Cl - of the aforementioned solidification bodies are all below 7.0×10 -4 g·m −2 ·d −1 .