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

ABSTRACT

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 SiO₂ with 1.3% recovery could be obtained, with a selectivity index of 27.4.

KEYWORDS:

• Cassiterite
• Karagwe Ankole Belt
• xanthan gum
• adsorption
• zeta potential
• quartz
• flocculation
• flotation

Abbreviations

GC	=	Gasambya cassiterite
GT	=	gravity tails
XG	=	xanthan gum
STS	=	sodium trisilicate
NaOL	=	sodium oleate
MIBC	=	methyl isobutyl carbinol
IEP	=	iso-electric point
FTIR	=	Fourier Transform Infra-Red

Acknowledgments

CN and LM thank the Indian Institute of Science for the grant of international student scholarships for pursuing the PhD programme. The authors express their gratitude to the Government of Rwanda for authorising sample collection and exportation. The Rutongo cassiterite mining company is thanked for facilitating the field investigation. Prof. Ramananda Chakrabarti and Dr. Valens Hishamunda are sincerely thanked for their help during the ICP-MS measurements.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.