The work presented in this paper deals with the determination of optimum parameters during the partial acidulation of the phosphate ore of Djebel Onk (Algeria) and the determination of P 2 O 5 water-soluble. The first part is devoted to P 2 O 5 conversion rate during partial acidulation of phosphate with different particle sizes (80 μm, 160 μm and 250 μm). These conversion rates are obtained by performing a series of reactions between phosphate and sulfuric acid diluted from 10 to 50 wt% and with reaction times ranging from 10 to 50 minutes. The best conversion rate (38.78%) was obtained at a reaction time of 50 minutes with phosphate particle size of 80 μm and an acid concentration of 50 wt%. The second part, concerns the measurement of P 2 O 5 water-soluble of phosphate partially acidulated (PAPRs) with 40% and 50 wt% sulfuric acid. The percentage of P 2 O 5 soluble in water has reached 14.98% for PAPRs obtained with phosphate particle size of 80 μm and an acid of 50 wt%.

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In this work, some parameters during the partial acidulation by phosphoric acid of phosphate 53.75% BPL (bone phosphate of lime) having different particle sizes are determined. P 2 O 5 recovery is obtained by performing a series of reactions using phosphoric acid diluted from 10 to 40 wt.% and with reaction times ranging from 10 to 50 minutes. The best conversion rates are obtained with the following reaction parameters: phosphates size: 88-177 μm, reaction time: 50 minutes and phosphoric acid concentration: 40 wt.%. In the second part, the water-soluble P 2 O 5 of PAPRs (Partially Acidulated Phosphate Rocks) obtained with phosphoric acid 30% and 40 wt.% is measured. The results of experiments showed that the water-soluble P 2 O 5 has reached 15.2% for PAPRs obtained by reacting phosphate 88 μm with phosphoric acid 40 wt%.

The development of industrial processes designed to produce efficient fertilisers is nowadays of great importance, particularly in the field of farming. One way of producing phosphate fertilisers is by reacting phosphate rocks with nitric acid. In the present work, the kinetics of this reaction has been studied using phosphate mineral of the Djebel Onk mine (Algeria) and measurements of the conversion of P2O5 have been carried out by gravimetry. The effects of various operating parameters such as the reaction time, the reaction temperature, the nitric acid concentration and the size of the particle have been studied. The experimental conditions have been optimised and global kinetic data such as the reaction rate constant and the activation energy have been determined.