Rapid Fabrication of Granite-Based Glass-Ceramics via Laser Sintering for Immobilization of Complex Radioactive Waste

Simple, rapid, and efficient sintering is a crucial step in the process of high temperature composites fabrication, and the fast reaction mechanism is of great scientific significance. For the first time, this study employs laser sintering technology to immobilize simulated wastes after trialkyl phosphine oxide (TRPO) process using natural granite as the host matrix. This method decreased the sintering cycle from about 10 h using traditional Joule heating to less than 5 min. The synthesized waste forms are characterized via XRD, FT-IR, XPS, and SEM-EDS to elucidate the structural change of complex aluminosilicate. Their mechanical properties and chemical durability have also been evaluated. Results show that varying from the conventional method, the laser sintered samples exhibit a perfectly regular crystal growth. As the waste loading increases (within 10–50 wt.%), more apatite crystals form in the glass-based waste forms of samples prepared by laser sintering, which facilitates the understanding of the changes in waste content. Moreover, the increased incorporated waste cations gradually depolymerize the glass network structure, promoting the transition from the glass to the glass-ceramic phase. After 28 days of leaching treatment, the normalized leaching rates of La, Ce, and Nd in the waste forms reached ∼10 −9 g·m −2 ·d −1 . These findings indicate that natural granite as well as laser sintering technology holds significant research value for the efficient immobilization of complex radioactive wastes.