温度对放射性含氟浓缩液磷酸盐水合陶瓷固化体的性能影响

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

以KH_(2)PO_(4)、重烧MgO、硼砂、硅灰等为原料,20~1000℃下制备磷酸盐水合陶瓷并固化模拟放射性含氟浓缩液,研究固化体的物相组成、微观形貌、力学性能、孔隙率和元素浸出等。结果表明:随着温度升高,固化体内部最初的结构发生坍塌,抗压强度降低、孔隙率增大;温度达到800℃后,磷酸盐水合陶瓷固化体生成新矿相Mg_(7)F_(2)(SiO_(4))_(3)、Mg_(2)SiO_(4)、Mg_(3)B_(2)O_(6)等,组成了光滑致密的网络框架,抗压强度回升,孔隙率降低;生成的陶瓷矿相有助于增加元素滞留能力,对Cs主要是物理阻碍作用,对F主要是化学作用。

In this paper,phosphate hydrated ceramic waste form was prepared by simulating the radioactive fluorine-containing concentrated liquid with KH_(2)PO_(4),dead burned magnesium oxide,borax and silica fume at 20-1000℃.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 Mg_(7)F_(2)(SiO_(4))_(3),Mg_(2)SiO_(4) and Mg_(3)B_(2)O_(6) 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.