Densification study of sodium zirconium phosphate-type ceramic for immobilizing radionuclides of Sr prepared with microwave sintering from uranium tailing sand
摘要
Strontium zirconium phosphate (SrZr4(PO4)6) ceramics has high density and chemical inertness, which can safely and effectively immobilize the divalent fission product Sr in the ceramic matrix. In this study, a novel SrZr4(PO4)6 ceramic was synthesized using microwave sintering of uranium tailings. This method features shorter sintering times and efficient energy use. Sr replaces Na in sodium zirconium phosphate (NaZr2(PO4)3) due to similar ionic radii, transforming it into SrZr4(PO4)6 ceramics. The results showed that the sintered samples prepared by holding at 1200 °C for 50 min, which the density of the solidified body reached up to 3.2 g/cm3.The ceramics showcase outstanding leach resistance, with Sr leaching rates far below the nuclear industry standard (1 × 10−2 g m−2 d−1). Similarly, the leaching rates for Na, Zr, P, and Si (10–4–10–6, 10–6–10–8, 10–3–10–4, and 10–2–10−3 g m−2 d−1) are significantly lower than industry standards.