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Critical assessment of activity coefficients of oxides in molten binary and ternary silicates, aluminates and aluminosilicates
Author(s) -
Turkdogan E. T.
Publication year - 2001
Publication title -
steel research
Language(s) - English
Resource type - Journals
eISSN - 1869-344X
pISSN - 0177-4832
DOI - 10.1002/srin.200100104
Subject(s) - ternary operation , aluminosilicate , ternary numeral system , mole fraction , oxide , thermodynamics , mineralogy , activity coefficient , chemistry , binary system , materials science , binary number , metallurgy , organic chemistry , physics , aqueous solution , arithmetic , mathematics , computer science , programming language , catalysis
Critical assessment is made of the activity coefficients of CaO, MgO, MnO, FeO, Al 2 O 3 and SiO 2 in molten silicates, aluminates and aluminosilicates. In this assessment due consideration is given to the consistency of the free energies of formation of the interoxide compounds derived from the oxide activity data, compared with those derived from the compiled thermochemical data. For most oxides, it is found that by using an empirical formulation of the melt composition in ternary systems, the composition dependence of the oxide activity coefficient, γO X , can be represented by a single curve. For example, over a wide composition range in the FeO‐CaO‐SiO 2 system, the log(γCaO) is a single function of the melt composition in mol fraction as ( ᵡ SiO 2 + 0.3 x FeO); this relation being similar to that in the binary CaO‐SiO 2 melts. Therefore, with respect to γCaO, this ternary system is reduced to a pseudo binary system as x CaO ‐ ( ᵡ SiO 2 + 0.3 x FeO). With respect to γCaO, the ternary system CaO‐Al 2 O 3 ‐SiO 2 is reduced to a pseudo binary system as x CaO ‐ ( ᵡ SiO 2 + 0.4 x Al 2 O 3 ). With γSiO 2 , this ternary system is reduced to a pseudo binary system as ( ᵡ CaO + x Al 2 O 3 ) ‐ x SiO 2 .