Xanthan gum based investigations into the surface chemistry of cassiterite and beneficiation of cassiterite tailings

The surface chemistry of cassiterite mineral and selective dispersion-flocculation-flotation studies on cassiterite tailings have been investigated using xanthan gum. Mineralogical studies indicate that quartz is the major mineral encapsulating cassiterite. The results of the adsorption, electrokinetic, co-precipitation, and Fourier Transform Infrared spectroscopic studies indicate that xanthan gum adsorbs on cassiterite by both physical and chemical forces. The adsorption density of xanthan gum for cassiterite decreases with an increase in pH, whereas it does not adsorb on quartz in the pH range of 3 to 12. The Gibbs free energy of adsorption for cassiterite is determined to be -35.7 kJ/mole, indicative of chemisorption. The zeta potential of cassiterite becomes more negative and its isoelectric point is shifted to more acidic pH values, attesting to specific adsorption of xanthan gum, whereas that of quartz remains unaltered, after its addition. The Fourier Transform Infrared spectroscopic investigations reveal that the adsorption of xanthan gum on cassiterite is governed by both hydrogen bonding and chemical interaction. The complexation of xanthan gum with Sn ions in the bulk solution is confirmed by dissolution and co-precipitation studies. Selective dispersion-flocculation-flotation tests on gravity tailings from Gasambya mines, Rutongo, Rwanda, demonstrate that a cleaner concentrate of 64.8% grade of Sn with 89% recovery, containing 1.9% grade of SiO(2)with 1.3% recovery could be obtained, with a selectivity index of 27.4.