Thermodynamic Modeling of Ilmenite Smelting and Impurity Distribution

Pigment production utilizes TiO₂-rich slags produced by the ilmenite smelting process which is sensitive to impurity levels in the titania slag. Thermodynamic analyses of ilmenite smelting were conducted to outline a path for process improvement. Specifically, the distribution of Ti and Fe, as well as a wide range of impurities, including V, Cr, Mn, Al, Si, Ca, Mg, P, and S, between the titania slag and molten iron were investigated. A comprehensive literature review was conducted to adequately ascertain the chemical compositions of ilmenite concentrates, which are among the most critical operational parameters in ilmenite smelting. Additionally, the quality requirements regarding impurity contents in the raw materials for TiO₂ pigment production were reviewed. The partition coefficients of elements between slag and metal determined as a function of process variables (i.e., oxygen partial pressure, temperature, and MgO/(Al₂O₃ + SiO₂) ratio) has been presented. Moreover, an in-depth analysis of the oxygen potentials during the ilmenite smelting process and the analysis of slag viscosity in corresponding process conditions have been shown. The analysis results are compared to the experimental data reported in the literature.