Influence of Glass Structure on the Dissolution Behavior of Fe from Glassy Slag of CaO-SiO2-FeOx System

Glassy slag of CaO-SiO2-FeOx systems is an important mineral phase of steelmaking slag when being used as a fertilizer for paddy fields, because this glassy phase can easily dissolve Fe and can stabilize hydrogen sulfide and suppresses over reduction. Structural analysis using Raman spectroscopy and Si-29 NMR was performed to clarify the mechanism of dissolution of the glassy slag of CaO-SiO2-FeOx systems in aqueous solutions, similar to the soil conditions of a paddy field. These results were then compared to the leaching results reported previously. The structural unit of SiO4 tetrahedra in the glassy oxide showed a decrease in the fraction of Q(2) and Q(3) and an increase in the fraction of Q(0) and Q(1) with increasing basicity and FeO content. Both the Raman and NMR spectra showed a significant decrease in Q(0) and Q(1) peaks after leaching, indicating that the Q(0) and Q(1) in the glassy slag were selectively dissolved. A comparison between the average number of bridging oxygens measured by Raman spectroscopy and the amount calculated by composition showed that a deviation occurs and increases when the basicity and FeO content are high. Based on this, it was assumed that some FeO started to bond to bridging oxygens.