The effect of FetO Content on MgO Solubilities in Lime-based Slags

Abstract

It was attempted to quantitatively elucidate the effect of Fe t O content on MgO solubilities in lime-based slags using the measured data of MgO solubility in the slags. The magnesia capacities of the lime-based liquid slags were nicely correlated with the optical basicities in case the ideal solution was assumed for the magnesiowustite saturation phase which is actually in equilibrium with the slags. The substitution of MgO for CaO in lime-based slags increased the activity coefficient of Fe t O for the constant activity of Fe t O, resulting in decreasing Fe t O content in the slags. It is believed that the Fe t O activities in metallurgical slags containing iron oxide play the decisive role in determining the MgO solubilities into the slags.KEY WORDS: MgO solubility; magnesia capacity; optical basicity; activity; activity coefficient; interaction coefficient.

Effect of FeO and Al2O3 on the MgO Solubility in CaO–SiO2–FeO–Al2O3–MgO Slag System at 1823 K

“…The relationship between optical basicity and MgO solubility in various slag systems 1, 4, 18, 24 and the present work is shown in Figure 2. The logarithm of the MgO solubility in molten slag (X MgO in slag ) decreases with increasing optical basicity and subsequently the activity of free oxygen ions($a_{{\rm O}^{2- } } $ ), which correlates well with the results of several previous works 1, 4–6, 8, 9, 14. Therefore, low basic slags will typically allow higher dissolution of MgO based refractory if the slag is not properly designed.…”

“…The concept of optical basicity has been adopted to evaluate the sulfide capacity, phosphate capacity, and MgO solubility 6–9 of the steelmaking slag system. However, it is reported that those modified values proposed by Duffy and Ingram,23 based on the Pauling electronegativity, does not accurately depict the basic slag systems and in particular those basic slag systems containing the transition metal oxide, such as MnO or FeO 25.…”

“…To extend the refractory life of furnaces, dolomite or MgO are typically added to the slag system to decrease the dissolution rate and the amount of MgO from the refractory and a fundamental understanding of MgO solubility in various slag systems has been the focus of much work 1–18…”

“…Jung et al6 reported the effect of MnO concentration on MgO solubility and calculated the Mg 2+ capacity of the slag system as suggested by Bergman7 using the MgO activity equilibrated with magnesiowüstite. Furthermore, the Mg 2+ capacity decreased with optical basicity 6, 8, 9…”

Effect of water vapour content in H2–H2O–CO–CO2mixtures on MgO solubility in slag under conditions of novel flash ironmaking technology

“…11 In magnesiowü stite, FeO coexists with MgO and thus affects a MgO . Thus, iron oxide activity a FeO in the magnesiowü stite layer, which equals a FeO in the slag at equilibrium, needs to be calculated.…”