Characterization and Modeling of Industrial Phosphoric Acids' Rheological Behavior: Impact of Magnesium Monoxide on Viscosity

ABSTRACT This study investigates the rheological behavior of industrial phosphoric acids (H 3 PO 4 ) produced at the JORF–LASFAR phosphoric plant in Morocco, with P 2 O 5 concentrations of 18%, 29%, 42%, and 54%. Rheological measurements were performed using a rotary cylinder rheometer over a shear rate range of 1–1000 s −1 . The influence of temperature, density, and magnesium monoxide (MgO) content on the flow behavior and viscosity of the acids was examined, and the fluid flow activation energy ( Ea ) was determined for each concentration. The results indicate that phosphoric acid with 54% P 2 O 5 exhibits dilatant behavior in the temperature range of 40°C–80°C while showing Newtonian behavior at lower temperatures between 25°C and 30°C. Furthermore, MgO content was found to have a significant effect on the rheological properties and viscosity of industrial phosphoric acids. The experimental rheological data were successfully analyzed and modeled using several empirical models, including the Casson, Bingham, power law, and Herschel–Bulkley models.