复配固化 / 稳定剂处理复合放射性重金属污染底泥: 以信江流域为例.

At present, domestic and international studies on the Xinjiang River basin are limited to the study of sediment heavy metal and nuclide pollution characteristics, and there are few studies on the treatment of heavy metals in sediments of dredged bottom sediments in the Xinjiang River basin. Therefore, taking the sediment sediment of the Xinjiang River (Yingtan section) as the research object, three stabilizers were used to solidify / stabilize the heavy metal polluted sediment with Portland cement, and a heavy metal solidification / stabilization technology of river sediment was studied, which can be used for the restoration and treatment of heavy metal in river sediment. The optimal ratio of cement and three stabilizers was determined by conducting an indoor unconfined compressive strength test and leaching toxicity, and the solid phase morphological characteristics, mineral composition, and changes of heavy metal speciation before and after the treatment were combined to investigate the solidification and stabilization mechanisms of heavy metals Pb and U in the bottom sediments. The results show that the optimal formulation is 30% cement, 1∶ 1 potassium dihydrogen phosphate (Molar ratio of phosphorus to heavy metals), 5% bentonite, and 5% fly ash, under this experimental condition. The ratio of two heavy metals Pb and U active states in the substrate is reduced by about 30% after treatment with the compound reagent, and the method effectively limited the migration of heavy metals Pb and U in the substrate. SEM( scanning electron microscope) and XRD(X-ray diffraction) analysis show that the main hydration products in the cured body are hydrated calcium silicate (C-S-H), calcium alumina (Aft), and bentonite agglomerates, which can increase the strength of the curing body through the cementation. The hydration products can also adsorb and encapsulate heavy metals in the sediments. Result elucidate the mechanism of heavy metal solidification / stabilization technology for river sediment and find that the technology also has a better stabilization effect on radionuclides, which can provide a reference basis and technical support for the dredged sediment project in the Xinjiang River basin and its surrounding site soil treatment. [ABSTRACT FROM AUTHOR]