A NATURAL MATERIAL FOR DESULPHATION OF THE 29% P2O5 PHOSPHORIC ACID: MODELING AND OPTIMIZATION

The natural material made from dolomite, quartz and illite is used for 29% P2O5 phosphoric acid desulphation in order to reduce the unwanted effects due to a solid genesis during the phosphoric acid concentration process. For eventual valorization and uses of this material on an industrial scale, a simple protocol which can be inserted into the manufacturing process, is proposed for phosphoric acid pre-treatment. This protocol modeling is performed according to the phosphoric acid quality obtained by sulfuric acid attack, and considering three main factors: amount of natural material (Q), temperature (T) and time (t) needed for desulphation. For an efficient removal of sulphates, full factorial design methodology has afforded a statistically validated model (R² = 99.94%) able to predict the optimal conditions (Q, T, t) and taking in consideration the initial amount of sulphate in the phosphoric acid to be pretreated.