Thermodynamic analysis of chemical processing of iron-titanium ores: calculation of thermochemical constants

The thermodynamic analysis method of chemical processing for refractory iron-titanium ores is increasingly utilized to enhance the efficiency of experimental research by reducing energy and resource consumption. Despite its growing application, the current methods for calculating the thermochemical characteristics of compounds containing many critically important metals need further refinement. This research addresses this issue by introducing improvements to the methods used for calculating thermochemical constants for irontitanium and other oxides. The study focuses on commonly found minerals such as ilmenite, magnetite, perovskite, and pseudobrookite under standard conditions. These improvements provide a solid foundation for thermodynamic analysis, specifically to identify potential phase transformations that may occur during the chemical processing of complex ores. To achieve this, a hyperbolic model was employed, which takes into account the detailed internal structure of the compounds, including the type of crystal lattice and the number of occupied positions. Using this model, the study calculated the heat capacity and entropy for compounds within the Fe–Ti–O system and developed a curve that shows how heat capacity varies with temperature. Moreover, a new method was proposed for calculating the standard enthalpy of formation of these oxides. These refined calculation methods offer more accurate empirical data for iron-titanium and other oxides and can predict the heat capacity and standard enthalpy of formation for less well-studied compounds. When comparing the new calculations to reference data, the results showed good convergence, with relative errors for heat capacity, entropy, and standard enthalpy of formation at about 1.4 %. This accuracy is significantly better than that of the traditional additive methods, showing a 20-fold improvement. The calculation methods proposed in this research provide a straightforward and reliable means of thermodynamic analysis for understanding phase transformations. They have the potential to significantly advance energy- and resource-efficient technologies in mineral processing, applicable to both natural exogenous-hypergene environments and the processing of refractory iron-titanium ores.This research was conducted under the State Assignment of the Institute of Geology of the Federal Research Center Komi Scientific Center of the Ural Branch of the Russian Academy of Sciences.