Effect of Temperature on Performance of Radioactive Fluorine-Containing Concentrated Liquid Phosphate Hydrate Ceramics Solidification

In this paper, phosphate hydrated ceramic waste form was prepared by simulating the radioactive fluorine-containing concentrated liquid with KH₂PO₄, dead burned magnesium oxide, borax and silica fume at 20-1 000 ℃. The phase composition, microstructure, mechanical properties, porosity and element leaching of the solidified body obtained at different temperatures were studied. The results show that with the increase of temperature, the initial structure of the solidified body collapses, the compressive strength decreases and the porosity increases. When the temperature reaches 800 ℃, some new ore phases of Mg₇F₂(SiO₄)₃, Mg₂SiO₄ and Mg₃B₂O₆ are generated. The smooth and dense network frame contribute to an increasing of the compressive strength and a decreasing of the porosity. The generated ceramic mineralization contributes to the increase of element retention capacity, which is considered that it is a physical effect on Cs and a chemical effect on F.