Characterization and production of Turkish nepheline syenites for industrial applications

Nepheline syenite, which is a silica-poor crystalline rock, competes with feldspar in applications such as glass, ceramic filler, and pigment industries. While its appearance is medium coarse granular like granite, main differences between them are nepheline syenite is silica poor, and contains high alumina and alkali content. Turkey has considerable nepheline syenite deposits in Kirşehir Region, and they contain 1.3% Fe₂O₃ on average, thus cannot be used unless beneficiated by flotation or/and magnetic separation. In this paper, physical and physicochemical experiments were carried out to improve the quality of nepheline syenite ore. After determinations of chemical, mineralogical, and properties of the sample, three different technologies such as flotation, magnetic separation, and leaching were applied on the ore sample, separately and combined. The obtained results showed that the magnetic separation alone could not produce a nepheline syenite concentrate assaying 0.45% Fe₂O₃. It was not also possible to obtain a nepheline concentrate less than 0.25% Fe₂O₃ adapting optimum flotation conditions. The best results were found in combination of the high intensity wet magnetic separation and flotation between -212+63 μm particle size, and a final concentrate with 0.20% Fe₂O₃ and 0.01% TiO₂ was obtained. The leaching experiments were conducted to further decrease Fe₂O₃ content. Finally, a saleable nepheline syenite concentrate for tile, sanitary ware, electrode, glass, and fiberglass industries was obtained with 6.63% K₂O, 9.02% Na₂O, 0.15% Fe₂O₃, and 0.01% TiO₂ by the weight of 63.9% at the end of the experiments.