(148a) Enhancing the Filtration Rate of Phosphogypsum Using Polymers

Phosphoric acid Phosphoric acid is an important intermediate product for production of fertilizers; it is produced either by wet process or by thermal process.  The wet process using sulfuric acid is the most comment used process, in wish the phosphate rock ([fluor-apatite Ca₁₀F₂ (PO₄ )₆] is dried, crushed, and then continuously fed into the reactor and reacted (digested) with sulfuric acid (H2SO4). The reaction led to the production of phosphoric acid (H3PO4) and calcium sulfate dihydrate or phosphogypsum (CaSO4·2H2O).Phosphogypsum is separated from the reaction solution by filtration.

Filtration is a key operation in the manufacturing process of phosphoric acid, the objective of this operation is to separate the phosphogypsum and phosphoric acid. My presentation will be subdevised on two main parts; in the first part I will discuss the parameters that affect the filtration operation for the separation of phosphoric acid from phosphogypsum cake. In the second part, I will present a result of study for the filtration rate improvement and the reduction of P2O5 losses in the gypsum cake by using a suitable polymer. The results of this study are based on the online measurement of filtration rate and soluble content of P2O5 in gypsum cake, using bench scale of filtration unit.  The study have been conducted in the case of two different process for phosphoric acid production  Rhone Poulenc and Prayon.