Cell model proposed by H. Gaye and J. Welfringer [1] is one of universal thermodynamic models of refining slag where energy parameters are mainly accessed by comparison of phase boundary of multi-component liquid slag and precipitating solid phase, sulfide capacity and phosphate capacity of slag. These values come from the result of equilibrium between slag and others, which are solid oxides and liquid steels. Therefore, if some evaluated values of the others are changed, the accessed energy parameters of slag must be re-accessed in order to satisfy the equilibrium relation with them.
In the cell model, the fractions of heterogeneous cation pairs are obtained which compose cells with an oxygen atom in between by minimizing free energy of slag with the energy parameters. Therefore, if the fractions of heterogeneous cation pairs in slag can be evaluated some how, the energy parameter values in the slag can be evaluated by itself directly independent from the equilibrium relation with other phases. By using NMR the fractions can be measured and the energy parameter values can be assessed so that the calculated fractions in the slag with its minimum of free energy coincides with the measurement. As a cross check of the assessment of the energy parameter values, ab initio calculation of formation energy of heterogeneous cation pairs and interaction energy between cells can be utilized.
From 17OMAS spectrum and 27Al→17O CP/MAS spectrum of a slag full labeled and calcinated at 1400 centigrade degree, whose chemical composition is 38.23 mass% SiO2-15.68 mass% Al2O3-46.08 mass% CaO, the ratio of NBO/BO in the slag was determined as 42/58. On the other hand the ratio was calculated by the use of cell model in Solgasmix and the value was 36/64. This agreement of the first trial gives a good expectation to the proposed method.
[1] H. Gaye and J. Welfringer, 2nd Int. Sympo. on “Metallurgical slags and flues”, Warrendale, P.A., TMS-AIME, Ed. H. A. Fine and D. R. Gaskell, 1984, 357.