Structural and thermal investigations of a Tunisian natural phosphate rock

Tunisian natural phosphate rock from M’dhilla deposits are characterized by different methods. The principal constituent of the phosphate rock sample is the carbonate fluoroapatite phase to which other clay and siliceous mineral; sulfates, carbonates and organic matter are associated. The crystallographic structure of natural phosphate was examined by powder X-Ray diffraction (XRD) at different temperatures of calcinations. The XRD diagrams show a significant structure change with increasing of the temperature to 1100 °C. The MAS-NMR technique was used to study the carbon, phosphorus, silicon and fluoride environment. The result confirms the single phosphate apatitic phase; the NMR study also indicates the presence of a small amount of organic compounds which was detected by chemical analysis (only 0.6%), IR spectroscopy and thermogravimetric analysis.