| With the rapid development of the nuclear industry, radioactive waste liquid on the ecological environment and human health hazards have gradually been valued.As annual output of the largest industrial waste in China, the pressure of the environment from fly ash increases rapidly, and how to disposal fly ash in recycle method has aroused widespread concern.In present paper, two advantages of fly ash are used, one is to be used as the raw material for the zeolite with high ion exchange capacity, and the other is to have the properties of gelation.After separation and enrichment of simulated nuclear (Sr2+, Cs+) with zeolite from fly ash, following, original fly ash was used to solidify the fly ash based zeolite. Ultimately, we can dispose of radioactive waste liquid in a safe way and achieve the purpose of waste treatment and disposal.First of all, based on the traditional method of alkali fusion, this paper have presented the process of removing silicon, and have established the technology system of two kinds of zeolite A with alkali fusion and de silicon synchronization.The effects of different parameters such as NaOH concentration, crystallization time and crystallization temperature on the synthesis were studied, and the results showed that the synthesis conditions of the highest quality was NaOH concentration of 2mol/L, crystallization time of 12 hours, crystallization temperature of 90?. At the same time, XRD, SEM, FT-IR, TG-DTA and other testing methods were used to characterize zeolite (I) and zeolite (?) in detail, and then, the quality of the synthetic zeolite was determined.The results reveal that the zeolite (?) has the characteristics of high crystallinity, small grain size, large ion exchange capacity and less impurities, which can be used in commercial applications such as detergent.Correspondingly, the zeolite (I) contained more impurities, but it still had a large ion exchange capacity, which can be used in the treatment of wastewater.The following, According to the quality of two kinds of zeolite A, the zeolite (I) was applied to simulated radioactive nuclide pollution disposal, and the adsorption properties of zeolite (I) of simulated radioactive nuclides Sr and Cs were investigated through the static balance test.The results showed that the synthesized zeolite had good adsorption capacity for Sr and Cs, and the theoretical maximum adsorption capacity reached 87.20mg/g,106.10mg/g. When the zeolite dosage was more than 5g/L, the removal rate of Sr2+ and Cs2+ more than 95%; when the dosage was lOg/L, the removal rate of Sr2+ and Cs2+ nearly 100%.Although the ionic strength increased from 0 to 0.1M, the adsorption capacity was still maintained at a high level.By comparing the XRD and FT-IR Spectrums before and after adsorption, and combining with the fitting analysis of the adsorption model, we believe that the adsorption on synthetic zeolite Sr2+, Cs+ was mainly physical adsorption.Finally, the synthesis of zeolite A was applied in the final nuclide curing, the original fly ash, zeolite, simulated nuclide and water glass as raw materials, according to the national standard preparation of solidified body, and the curing properties of the solidified body were detected. The results showed that when the zeolite content was 10% and 50%, the compressive strength of the solidified body is not up to the standard, in the dosage of 20?30%, the compressive strength was higher than the national standard. The leaching rate of Sr2+ and Cs+ in the solidified body decreased with the increase of the content of zeolite, Comparison of Sr2+ and Cs+ leaching rate, the 42 days leaching rate of Sr2+ was 1.87?8.75×10-6 cm·d-1, the 42 day leaching rate of Cs+ was 3.44?8.63×10-5 cm·d-1. This is far lower than the national standard limit value of performance of solidified radioactive waste.In general, it exhibitedexcellent anti leaching performance.The results showed that the resistance to Sr2+ and Cs+ were different, the leaching rate of Sr2 was significantly less than that of Cs+.It can be seen that the curing effect of Sr2+ is better than Cs+. |
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