Modelling of a solid dissolution in liquid with chemical reaction: Application to the attack reaction of phosphate by sulphuric acid

Abstract

This paper aims at the determination of the kinetics and thermodynamics of a liquid–solid reaction: the attack reaction of the phosphate ore by sulphuric acid. This reaction, which is used industrially for the production of phosphoric acid, has two stages, the first of which consists in the dissolution of phosphate ore in the diluted phosphoric acid diluted and the second relates to the attack of the dissolved ore by sulphuric acid. The thermodynamic properties and the kinetic parameters of each reaction are determined using a calorimetric approach. The complete kinetic study of the step in dissolving the phosphate ore was conducted to develop a kinetic model involving the process of transfer kinetic liquid–solid and the chemical kinetic processes. This model takes into account the coupling between the mass and heat balance and the multitude particles' sizes of phosphate and the stirring speed. The study of the attack of monocalcium phosphate by sulphuric acid allows the evaluation of the reaction order and the values of various parameters that describe the kinetic model of the precipitation reaction. The comparison of different parameters determined with those reported in the literature shows the reliability and the relevance of the proposed methodology.

Kinetics of sulphur dissolution in lithium–sulphur batteries

“…The sulphur is in solid phase as S 8 allotrope [25,26] in contact with the electrolyte solution via a distinct plane solid-liquid interface of area A. The dissolution kinetics at the solid-liquid interface is described by the following equations [27][28][29]:…”

Dissolution of Tunisian phosphate ore by a mixture of sulfuric and phosphoric acid: Kinetics study by means of differential reaction calorimetry

“…Nevertheless, phosphate ore dissolution by sulfuric acid remains the most extensively used process [22] and over 90% of the phosphoric acid produced globally is manufactured through the decomposition of phosphate ore with sulfuric acid as an acidulate [23]. The decomposition of phosphate rocks using aqueous sulfuric acid has been studied by several authors [24][25][26][27][28][29][30][31]. Sevim et al [24] dissolved Turkish mineral phosphate in sulfuric acid at 14-70ºC showing that the reaction rate belongs to a solid-to-liquid ratio, temperature and particle size.…”

Attack of Tunisian Phosphate Ore by a Mixture of Sulfuric and Phosphoric Acid: Thermochemical Study by Means of Differential Reaction Calorimetry

“…It is well know that natural phosphates cannot be used directly as a fertilizer because of their insolubility to make them available to plants, phosphate are dissolved by acids. A number of published studies devoted to phosphate synthetic [9]- [16] or natural [17]- [37] in single aqueous acid solutions were carried such as phosphoric acid [10] [23], succinic acid [24], nitric acid [28] and hydrochloric acid [9] [13] [26] [27] or mixture acid solution [33] [34] [35] [36] in literature to clarify the kinetics and process mechanism and improve the performance of phosphate attack. However, phosphate rocks decomposition by sulfuric acid remains the most widely used method [29] [30] [21] [32] and over 90% of the phosphoric acid produced worldwide is manufactured by digestion of phosphate rocks with sulfuric acid as an acidulant [37].…”