Thermo-kinetic and Physico-Chemical Modeling of Processes Generating Scaling Problems in Phosphoric Acid and Fertilizers Production Industries

The wet-process phosphoric acid (WPPA) production is generally based on the use of sulfuric acid (H2SO4) for phosphate ore attack. One of the main issues encountered in this process is related to the uncontrolled formation of mineral deposits at sensitive steps. In the generated complex aqueous systems, the dissolved species and the resulting physicochemical interactions are closely dependent on the variability of both the phosphate rock quality and the operating conditions of the process (40-95 °C; H3PO4 and H2SO4 concentrations up to 20 mol/kg H2O, typically). A collaborative project (CA2PHOS) between OCP and BRGM aims to develop a computational tool dedicated to predict and quantify these mineral deposits in the context of WPPA production. The integrated work presented allows one to gain insight into the understanding of the complex behavior of such systems. It involves specific data such as the activity of water, measured by the hygroscopic method, the density and the chemical composition of the very highly saline aqueous solutions of interest, characteristics of the deposited minerals, and the use of the Pitzer formalism for the thermodynamic modeling of such complex system.