Properties of Mestaoua evaporites (southern Tunisia) for plaster industry

Abstract

Southern Tunisia exhibited thick series of naturally occurring gypsum deposits. Those evaporites may constitute important feeds for plaster industry. An in-depth study of the evaporites deposits outcropping in the Tataouine area (southern Tunisia) has been undertaken to find out their detailed physical and chemical properties. Ten gypseous samples collected from the Oued El Ghar study site were characterized using several techniques. Thus, physical–chemical characterization concerned chemical analysis by X-ray fluorescence, mineralogical analysis by X-ray diffraction and spectroscopic analysis by Fourier transform infrared. Other techniques including thermogravimetric analysis and textural analysis were used for the assessment of the Mestaoua gypsum deposits. It was found that the studied samples were mainly composed of sulfates (as $$ {\text{SO}}_{3}^{ - } $$ ) and calcium oxide (CaO) together with minor amounts of silica, iron and magnesium oxides. This chemical composition was completed by specific surface area measurements (21.25 m2/g), volumic mass (2.33 g/cm3) and porosity (17.2 %). A technical specifications chart was established to gather the main requirements that will be used as criteria for the selection of products to be manufactured. Based on the above-mentioned analyses, natural gypsum deposits of the Mestaoua area showed the required technical specifications for use as feeds for the manufacture of plaster and derivatives, adjuvant, chemicals, among other industrial uses.