Collier N C, Milestone N B, Hill J, Godfrey I H
Immobilisation Science Laboratory, Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK.
Waste Manag. 2006;26(7):769-75. doi: 10.1016/j.wasman.2006.01.031. Epub 2006 Apr 18.
An iron hydroxide floc is used as treatment for adsorbing low amounts of actinides during nuclear fuel re-processing. This waste is cemented only after pre-treatment with Ca(OH)(2). Characterisation of all simulant material has been undertaken using XRD, TGA and SEM/EDS. The floc is a moderately alkaline colloidal slurry containing approximately 15wt% solids, with the main particulate being an amorphous hydrated iron oxide. The main phase formed during pre-treatment appears to be an X-ray amorphous hydrated calcium-ferrate phase. Embedded within this are small amounts of crystalline Ca(OH)(2), calcite, Fe(6)(OH)(12)(CO(3)), Ca(6)Fe(2)(SO(4))(3)(OH)(12).26H(2)O and Ca(3)B(2)O(6), and can form depending on concentrations of Ca(OH)(2) and time. Apart from Ca(OH)(2) and calcite, none of the crystalline phases detected during pre-treatment are detected when the floc is encapsulated in an OPC/PFA composite cement hydrated for 90 days. The main crystalline phase detected in the hardened wasteform is a solid solution hydrogarnet, Ca(3)AlFe(SiO(4))(OH)(8), known as C(3)(A,F)SH(4) in cement chemistry nomenclature.
氢氧化铁絮凝物用于核燃料后处理过程中吸附少量锕系元素。这种废物仅在经过Ca(OH)₂预处理后才进行固结。已使用XRD、TGA和SEM/EDS对所有模拟材料进行了表征。该絮凝物是一种中等碱性的胶体浆料，含有约15wt%的固体，主要颗粒为无定形水合氧化铁。预处理过程中形成的主要相似乎是一种X射线无定形水合钙铁酸盐相。其中嵌入了少量的结晶Ca(OH)₂、方解石、Fe₆(OH)₁₂(CO₃)、Ca₆Fe₂(SO₄)₃(OH)₁₂·26H₂O和Ca₃B₂O₆，它们的形成取决于Ca(OH)₂的浓度和时间。当絮凝物被封装在水化90天的OPC/PFA复合水泥中时，除了Ca(OH)₂和方解石外，预处理过程中检测到的结晶相均未被检测到。在硬化的废物形式中检测到的主要结晶相是一种固溶体水石榴石，Ca₃AlFe(SiO₄)(OH)₈，在水泥化学命名法中称为C₃(A,F)SH₄。
