Enhancing flotation separation effect of fluorite and calcite with polysaccharide depressant tamarind seed gum

Abstract

Tamarind seed gum (TSG), a neutral polysaccharide extracted from the endosperm of tamarind seeds, was used as depressant to separate fluorite and calcite for the first time. Micro-flotation experiment results revealed that TSG has great influence on the floatability of calcite at pH range of 6–11, the flotation recovery of calcite was only 6.61% at pH 9.0, while the floatability of fluorite still kept excellence (flotation recovery 88.05%). Artificial mixed mineral experiment results indicated that TSG as depressant can successfully separate fluorite from calcite. Zeta potential analysis, Fourier transform infrared (FTIR) analysis and X-ray photoelectron spectroscopy (XPS) analysis results indicated that the adsorption capacity of NaOL on fluorite surface was much stronger than that of calcite in the presence of TSG. It was found that many active hydroxyl groups in TSG can complex with Ca2+ on the surface of calcite to prevent the adsorption of NaOL, while the interaction between NaOL and fluorite was still intense. Atomic force microscopy (AFM) images indicated that calcite surface presented a dense aggregation adsorption and higher roughness after treated with TSG. All results confirmed that there are significant differences in the adsorption behavior of TSG between fluorite and calcite, and separating the two minerals can be efficiently achieved by adding TSG.