掺合料对含氟放射性废液MKPC凝胶材料固化体性能的影响

Influence of Admixture on Property of Radioactive Fluoride Liquid Waste Solidified Form by MKPC

以KH_2PO_4、重烧MgO和硼砂按一定比例制备磷酸钾镁(MKPC)凝胶材料固化模拟含氟放射性废液,研究掺合料(石英砂、沸石、硅灰、粉煤灰)对固化体性能的影响。结果显示,掺合料不改变固化体的终凝时间,但影响其孔隙率,掺入粉煤灰后孔隙率降低,掺入硅灰则相反。固化体空气养护28 d后,抗压强度大于55 MPa,抗压强度的损失与孔隙率呈正比。所制备的固化体具有良好的抗浸出性能,浸出实验42 d后,模拟核素Sr^(2+)、Cs^+、Co^(2+)的浸出率和Cs^+的42 d累积浸出率低于GB 14569.1—2011的限值,F^-平均浸出浓度低于GB 5085.3—2007的限值。

In this paper,magnesium potassium phosphate cementitious (MKPC) material was preparaed by adding KH 2PO 4,dead-burned MgO and borax in a certain proportion to solidify simulated radioactive fluoride liquid waste.The influence of admixtures,such as quartz sand,zeolite,silica fume and fly ash,in the solidified forms was studied.The results show that admixtures don’t change the setting time of the solidified form,but influence its porosity.The porosity increases obviously after adding silica fume and decreases after adding fly ash.After cured 28 d,the compressive strength of the solidified forms is greater than 55 MPa.The loss rate of the compressive strength is proportional to porosity.The solidified forms prepared in this paper have good leaching resistance property.After 42 d leaching test,the leaching rate of simulated nuclides Sr^2+,Cs^+,Co^2+ and the 42 d cumulative leaching rate of simulated nuclide Cs+ are lower than the limit value of GB 14569.1-2011.Average leaching concentration of F- is lower than the limit value of GB 5085.3-2007.