A Structural Molar Volume Model for Oxide Melts Part III: Fe Oxide-Containing Melts
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I.
INTRODUCTION
MANY slag systems in the steelmaking process and non-ferrous metallurgical process contain significant amounts of iron oxide. For example, the CaO-FeOFe2O3-SiO2 slag is the main slag system of both the basic oxygen furnace (steelmaking process) and converter process of non-ferrous metals such as Cu and Zn. In addition, the slags for ferro-alloy production and electric arc furnace slags for steel production contain a large amount of iron oxide. Molar volume or density is one of the most fundamental physical properties of liquid slags and is required for the design of industrial processes. However, the molar volume of Fe oxide-containing slag is complex because of the redox reaction in slag producing both FeO and Fe2O3 in liquid state. The amount of FeO and Fe2O3 changes with slag composition, temperature, and oxygen partial pressure. Critical evaluation of all experimental molar volume data in the Li2O-Na2O-K2O-MgO-CaO-MnO-PbOAl2O3-SiO2 system, the modeling of molar volume of unary and binary melts, and demonstration of predictive ability of the present structural molar volume model in ternary and multicomponent melts were already presented in the Parts I and II of this series of studies.[1,2] The purpose of the present study is to critical review of the experimental molar volume data of the FeOFe2O3-Na2O-K2O-MgO-CaO-MnO-Al2O3-SiO2 system and modeling based on a structural molar volume
ERIC THIBODEAU, Graduate Student, and IN-HO JUNG, Associate Professor, are with the Department of Mining and Materials Engineering, McGill University, 3610 University Street, Montreal, QC H3A 0C5, Canada. Contact e-mail: [email protected] AIMEN E. GHERIBI, Research Associate, is with the Centre de Recherche en Calcul Thermochimique, Departement de Genie Chimique, Ecole Polytechnique de Montreal, C.P. 6079, Succ. Centre-ville, Montreal, QC H3C3A7, Canada. Manuscript submitted November 27, 2014. Article published online December 30, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS B
model. The molar volume parameters of pure FeO and Fe2O3 and hypothetical binary FeO-SiO2 and Fe2O3SiO2 melts were optimized in the present study based on the most reliable experimental data. Then the molar volumes of all ternary and multicomponent melts under any oxygen partial pressure can be accurately predicted from the present structure molar volume model.
II.
STRUCTURAL MOLAR VOLUME MODEL
A structural molar volume model for binary systems was presented in Part I of this study and its expansion to ternary and multicomponent systems was explained in Part II. A short review of the model is given below. The total number of oxygen (nt) in one mole of a M2O-…-MO-…-M2O3-…-SiO2 melt (where M is any metallic cation such as Na, Ca, Mg, Fe(II), Al, Fe(III), etc.) is nt ¼ XM2 O þ þ XMO þ þ 3XM2 O3 þ þ 2XSiO2 ; ½1 where X is the mole fraction of each respective oxide in the melt. Then the number of bridged oxygen (nOo ) in one mole of solution can be calculated by multiplying the mole fraction of Si–Si pairs (XSi–Si) in the
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