Modeling and Simulation of Hemihydrate Phosphoric Acid Plant

Abstract

In this paper, wet hemihydrate phosphoric acid process was modeled and simulated using ASPEN PLUS using properties of Sokoto Phosphate Rock to characterise the basic raw material. The process consisted of the reaction section, filtration section, and purification unit. Results of the simulation showed that the model developed in this study described the behavior of a real plant. Sensitivity analyses for the fundamental parameters were performed using the model. From the results of the sensitivity analyses, it was found that the temperature and pressure of the flash separator are the main factors that affect the purity of wet process phosphoric acid. At a temperature above 400°C, the purity of the phosphoric acid is maintained at 100%. This value changes at temperatures below 80°C where the phosphoric acid purity is maintained at 74%. This indicates that the purity of the acid increases with increase in flash separator temperature. The purity of the phosphoric acid varies inversely with the pressure of the flash separator. The purity of the phosphoric acid is about 84% at 0.5 bar. It decreases gradually with increase in pressure.