Environmental hazards due to alkali elution can be mitigated by investigating the dissolution kinetics of calcium silicate mineral phases in water. This study demonstrated the effect of the silicate skeleton structure on the dissolution kinetics of calcium silicate mineral phases in water. The time dependence of the Ca-Si relative release ratio during leaching indicated the preferential elution of Ca to Si in the initial stage of dissolution. The formation of a Ca-depleted layer on the surface of the leached sample was confirmed by X-ray photoelectron spectroscopy and time-of-flight secondary-ion mass spectrometry. The elution kinetics of Ca and Si were determined by the semi-infinite diffusion model and the detachment reaction of the intermediate phase that was formed on the surface of the mineral by hydration, respectively. Furthermore, the nanoscale intermediate phase was observed by transmission electron microscopy. The diffusion coefficient of Ca in the leached layer and the reaction-rate coefficient of Si were obtained from the elution kinetics of Ca and Si, respectively, and these decreased with the increase in the degree of polymerization of the silicate skeleton structure that varied in the following sequence: calcio-olivine (γ-Ca2SiO4) > rankinite (Ca3Si2O7) ≈ wollastonite (β-CaSiO3) > pseudowollastonite (α-CaSiO3).
|ジャーナル||Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science|
|出版ステータス||Published - 2021 4|
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