Mineralogical and Micromorphological Characterization of Iron Impurity in Gedikler Bentonite Mine (Esme/Usak, Turkey)

Abstract

This paper deals with the determination of iron impurity in samples collected from the Gedikler (Esme) bentonite mine in Usak area, Turkey. Although the chemical analysis of the samples shows that their iron contents vary from 1.93 to 4.04 Fe₂O₃ %, any iron mineral could not be determined by X-ray diffraction (XRD) analysis in the raw samples. Hence, magnetic separation process was applied to the samples. XRD analysis followed by magnetic separation indicated that the major mineral of magnetic product (MP) is jarosite and there are minor amounts of smectite, kaolinite and opal-CT. In addition to XRD analysis of magnetic product, chemical analysis showed that it mainly consists of Fe₂O₃, K₂O, SO₄^2- and high LOI. In addition to confirm this deduction, the molecular equivalents of these elements, which were calculated based on these results, imply the presence of jarosite. These results were also supported by simultaneous thermo gravimetric/differential thermal analysis (TG/DTA) and infrared spectroscopy (IR) studies. Scanning electron microscopy (SEM) combined with energy-dispersive spectroscopy (EDS) analysis revealed that the magnetic product predominantly consists of pseudo cubic crystals in which mainly Fe, K, S, O and minor amount of Al is present. The presence of Al in crystals shows that some of the Fe positions are probably filled with Al. Based on these data, it is concluded that the iron mineral of the Gedikler bentonite mine is jarosite-alunite solid solution and it can be eliminated by magnetic separation easily.