Heat effects in the reaction of sulfuric acid with ilmenites influenced by initial temperature and acid concentration

Maciej Jabłoński,Andrzej Ściążko,Krzysztof Lubkowski,Sandra Tylutka

doi:10.2478/pjct-2021-0028

Abstract

Abstract The influence of temperature and sulfuric acid concentration on the enthalpy and the rate of heat release during the reaction of Norwegian and Australian ilmenites with sulfuric acid was determined. The experimental results obtained from calorimetric measurements were compared with theoretical calculations based on the oxide composition and the phase composition of the raw material. Experimentally determined heat of reaction for Norwegian ilmenite (900–940 kJ/kg) and Australian ilmenite (800–840 kJ/kg) showed good agreement with theoretical calculations based on the phase composition of the raw material. It was found that the enthalpy of ilmenites decomposition reaction does not depend on the concentration of sulfuric acid in the concentration range from 83% to 93%. It was also demonstrated that the temperature and concentration of sulfuric acid have a significant impact on the thermokinetics of the decomposition process, increasing the value of the average rate of temperature change.

Highlights

The reaction of titanium-bearing minerals with sulfuric acid is of great practical and technological importance, as it is the first stage in the production of titanium dioxide pigments by the sulfate method[1,2,3,4]
The thermal effect and thermokinetics of the sulfuric acid reaction with titanium raw materials strongly depend on such parameters as the initial concentration of sulfuric acid[18], reaction initiation temperature[19] and the particle size of the titanium raw material[20]
The enthalpy effect of the reaction has been calculated based on thermodynamic data for all components of the reaction mixture, taking into account a) the oxide composition, and b) the phase composition of the raw material

Summary

Introduction

The reaction of titanium-bearing minerals with sulfuric acid is of great practical and technological importance, as it is the first stage in the production of titanium dioxide pigments by the sulfate method[1,2,3,4]. The thermal effect and thermokinetics of the sulfuric acid reaction with titanium raw materials strongly depend on such parameters as the initial concentration of sulfuric acid[18], reaction initiation temperature[19] and the particle size of the titanium raw material[20]. The impact of these parameters on the course of the reaction is dependent on the elemental and phase composition of titanium raw materials[21]. Improper selection of the initial reaction parameters may lead to incomplete reaction of the reaction mixture, which in turn contributes to specific and measurable economic losses

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