Microwave Vitrification of Uranium Tailings: Microstructure and Mechanical Property

Abstract

In this work, the dense glass matrix of uranium tailings was successfully fabricated via microwave sintering process with Na2CO3 as a sintering aid. The effects of Na2CO3 additive and sintering temperature on the microstructure and mechanical properties of as-prepared solids were systematically investigated. XRD results confirmed the vitrified forms can be achieved at 1200°C within 30 min with 20 wt.% Na2CO3 addition. Importantly, the Na2CO3 additive significantly reduced the firing temperature from 1500°C to 1200°C and promoted densification. FT-IR analysis demonstrated that the main characteristic peaks of the sintered samples were attributed to the vibration of Si-O-Si. Microstructural studies presented the homogeneous distribution of glass phases. The results of mechanical properties of the sintered forms show that bulk density and Vickers hardness increased with increasing Na2CO3 content as well as sintering temperature, and the highest bulk density (2.45 ± 0.01 g/cm3) and Vickers hardness (823 ± 25 HV) were obtained at the temperature of 1300°C with 20 wt.% Na2CO3 addition, the heating rate of 20°C/min, and the soaking time of 30 min. It implied that the combination of microwave sintering with the appropriate addition of Na2CO3 would provide an efficient method for the immobilization of radionuclides in uranium tailings.

Wyzwania i możliwości odzysku w gospodarce odpadami podczas procesów wydobycia i wzbogacania rud zawierających uran i tor – przegląd

“…They also fulfil specific measurement requirements and enable the accurate assessment of U-wastes and potentially contaminated waste (Clark et al 2003). Characteristics of U-wastes include (Jiang et al 2020(Jiang et al , 2021(Jiang et al , 2022Wei et al 2021;liu et al 2021;Mao et al 2022):…”

“…The results showed that the leaching efficiency of U significantly increased when the wastes were subjected to microwave irradiation along with the composite oxidation of Fe 3 (III) and Mn(VII). (Wei et al 2021) investigated the production of a dense glass matrix of U-waste by microwave sintering. The addition of na 2 CO 3 as a sintering aid lowered the ignition temperature and promoted condensation, resulting in vitrified forms of waste.…”