Mineral characterization of the Oum El Khacheb phosphorites (Gafsa-Metlaoui basin; S Tunisia)

Abstract

The mineralogy of the Tunisian phosphatic series of the Jebel Oum El Khacheb deposit which belongs to the Gafsa-Metlaoui basin, located in the South of Tunisia, was studied. Chemical and mineralogical characterization of eight representative samples (2 mm–70 μm) were undertaken by X-ray diffraction, thermal analysis TG/DTA, Carbon and Sulfur analyzer and Atomic Absorption Spectroscopy. It was revealed that each phosphatic layer contains various silicates and carbonates. The X-ray diffraction results were supported by the Rietveld method to confirm the presence of certain minor phases (calcite, dolomite, bassanite and anorthoclase). The precision and accuracy of the quantitative-phase analysis, using the Rietveld method as a routine tool for process control, were highlighted. Keywords: Phosphorite, Mineralogy, Quantitative XRD, TGA–DTA