Preparation of silicate glass-ceramics nuclide solidified body using asbestos tailings and coal fly ash and solidification mechanism

Industrial solid waste poses serious risks to the human living environment and health owing to its diversity and complexity. In this work, asbestos tailings and coal fly ash were used as raw materials, and the trivalent actinide nuclide was simulated using Nd 2 O 3 . The silicate glass-ceramics nuclide solidified body was successfully prepared through melting, water quenching, and sintering methods. The properties of the solidified body and the solidification mechanism of the nuclide were studied via X-ray diffraction, Scanning electron microscope-energy dispersive spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and Atomic pair distribution function analysis. The results showed that the solidified body prepared via the molten water quenching–sintering method exhibited a unique microcrystalline structure, with properties that were significantly superior to those of traditional glass solidified bodies. Increasing the amount of Nd 2 O 3 further enhanced the stability of the solidified body. However, when the amount of Nd 2 O 3 exceeded 22 wt%, both the compressive strength and bulk density of the sample decreased. Therefore, the optimal package capacity of the solidified body for the nuclide Nd was 22 wt%. The leaching experiment demonstrated that the normalised leaching rate of Nd stabilised after 14 d and reached the order of 10 −5  g m −2  d −1 after 42 d, which indicated that the solidified body had excellent curing ability for nuclides. Analysis of the glass network structure revealed that Nd elements formed short-range ordered structures with Al, Si, Mg, O, and other elements through non-bridging oxygen bonds, thus becoming fixed in the amorphous phase of the solidified body. When the amount of Nd 2 O 3 exceeded 20 wt%, some short-range ordered structures containing Nd transitioned to form long-range ordered structures, which were stabilised in the crystal phase through lattice solidification. Overall, this study provides an experimental and theoretical basis for the solidification of highly radioactive nuclides using industrial solid waste.