Effect of FeOt Content and CaO/SiO2 Ratio on Hydrogen Dissolution in CaF2–CaO–SiO2‐Based
The solubility of hydrogen in the CaF2–CaO–SiO2–FeOt slag system
was studied to characterize the dependence of hydrogen dissolution behavior on the CaO/SiO2 ratio and the Fe3+/Fe2+
redox equilibrium at 1823 K. In an acidic slag composition, the dissolved hydrogen seems to exist as an incorporated hydroxyl, where the supplied water vapor reacts with the bridged oxygen (Oo) of the slag network. In a basic slag composition,
hydrogen dissolves as a free hydroxyl in the molten slag by reacting with the free oxygen (O2−). Using FTIR (Fourier transform infrared) and Raman spectroscopy, the addition of FeOt
depolymerized the slag structure in an acidic slag system, but polymerized the slag structure in a basic slag system as the FeOt content increased. Furthermore, the formation of γ‐ and δ‐FeO(OH)
was controlled by the amount of Fe2O3 present in the flux and increased at higher concentrations of Fe2O3.
At a fixed Fe2O3 content and with CaO/SiO2 ratios varying from 0.7 to 1.3, the hydrogen solubility
curve was parabolic as a function of CaO/SiO2, with a minimum near the CaO/SiO2 ratio of 1.0 and rapidly
increasing at CaO/SiO2 ratios above 1.0.