Immobilization Mechanism of Fluorine in Aqueous Solution with Calcium Aluminates

概要

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Immobilization of fluorine in aqueous solution with 3CaO · Al2O3 (C3A) and 12CaO · 7Al2O3(C12A7) has been investigated under the shaking and static conditions. The hydration products are identified by XRD and the microscopic observation has been made for the hydrated particles using electron microprobe analysis. It is found that the degree of immobilization of fluorine increases in the order of CA2<CA<C12A7<C3A and the immobilization of fluorine occurs through the formation of Ca3Al2(OH)12-xFx and C3A · Ca(OH)2-xFx · 18H2O. The former which contains a larger amount of F (x = 0–1.2) is the major hydration product for hydrated C3A, and the latter which contains a smaller amount of F (x = 0–0.12) is the dominant phase for hydrated C12A7. The conversion of the hexagonal hydrates of C2A · 8H2O and C3A · Ca(OH)2 · 18H2O to the cubic hydrate of Ca3Al2(OH)12 occurs rapidly in the case of C3A, while it occurs slowly in the case of C12A7. During this conversion the F- ion is incorporated into (OH-) site in the Ca3Al2(OH)12 phase.
社団法人日本鉄鋼協会の論文
2001-05-15