Textural And Mineralogical Studies Of Two Tunisian Sedimentary Phosphates Or Carbonated Fluorapatite Used In The Process Of Production Of Phosphoric Acid

Tunisian phosphate is a sedimentary rock and is the second major expense in producing phosphoric acid which is used mainly in fertilizer field. Phosphate is a mesoporous solid and has very large specific surface areas which often lead to greater activity due to increased dispersion of the active sites. The reaction between phosphate rocks and acids is essentially a surface reaction. Within the framework of valorization of Tunisian natural phosphate which is a carbonate fluorapatite or francolite and to establish the relations between the reactivity of phosphate rock and their physico-chemical properties.Two Tunisians deposits of phosphate were selected. Several techniques were used such as the SEM physisorption for textural study X-ray diffraction technique and Infra Red Spectroscopy for the mineralogical study. From the textural study we note that the two samples of phosphate have a mesoporous texture and all phosphate rocks contain many impurities. From the mineralogical study we note that the two main constituents of sedimentary phosphate rocks are apatite and calcium carbonate. The results obtained show a slight difference in physico-chemical properties between the two types of sedimentary phosphates and the dependence between the chemical reactivity and the structure of these phosphates.