A novel (1– x )SrZP– x NdPO 4 composite ceramic was designed to simultaneously enable uranium tailings utilization and the immobilization of divalent fission products (Sr) and trivalent surrogate nuclides (Nd). • Uranium tailings are directly upcycled into composite ceramics waste forms via microwave sintering. • A dual-phase SrZP/monazite structure enables simultaneous immobilization of Sr 2+ and Nd 3+ . • Rapid microwave sintering achieves high densification (4.24 g·cm −3 ) within 50 min at 1200 °C. • The composite ceramics exhibit enhanced mechanical strength up to 714.1 HV 1 . • Ultra-low leaching rates of Sr (10 –4 ) and Nd (10 –7 g·m −2 ·d –1 ) ensure long-term stability. As a primary byproduct of uranium mining and processing, Uranium tailings result in significant hazards for environment and human health owing to the presence of multivalent radioactive nuclides, especially for 226 Ra(II), 144 Nd(III), and 237 Np (III). Herein, we proposed a microwave one–step sintering of the uranium tailings to fabricate novel composite ceramics as (1– x )SrZP– x NdPO 4 ( x = 0, 0.2, 0.4, 0.6, 0.8, 1), suggesting the dual purposes of treating uranium tailings and immobilizing divalent fission products (FPs) and trivalent simulated nuclide. The phase evolution, microstructure, density, and chemical stability were systematically investigated for the sintered samples with different Sr/Nd ratios. As presented, the ceramics exhibit high densification without elemental enrichment via sintering at 1200 °C with a 50–min soak . As x increases in the crystalline phase, the content of monazite synchronously increases, leading to a maximum density of 4.24 g·cm −3 and a maximum Vickers hardness of 714.1 HV1 in final SrZP–NdPO 4 composite ceramics. More importantly, the SrZP–NdPO 4 composite ceramics demonstrate an excellent leaching resistance, correponding to the leaching rates of Sr and Nd as low as 10 –4 g·m −2 ·d –1 and 10 –7 g·m −2 ·d –1 over a 42–day period, respectively. This study offers a promising strategy for the long-term stabilization and safe disposal of the divalent FPs and trivalent radionuclides in uranium tailings via a ceramic solid-solution approach.
Li et al. (Wed,) studied this question.