Flotation separation of smithsonite from calcite with guar gum as depressant

Naturally, smithsonite and calcite have similar surface physico-chemical properties so as similar floatability, hence their separation via flotation has always been one of the difficult problems in mineral processing industry. To solve this dilemma, efficient flotation reagents which could expand the difference in surface properties could be a good bailout. In this study, guar gum was successfully employed as depressant for calcite during the smithsonite flotation, and its function mechanism were studied by micro flotation, and X-ray photoelectron spectroscopy (XPS) analysis, Fourier transform infrared (FT-IR) analysis, and Zeta potential measurement. The result of micro flotation showed that using guar gum as a depressant can effectively separate smithsonite from calcite by flotation; the analysis results of XPS, FT-IR, and Zeta potential measurements showed that the adsorption behavior of Guar gum on calcite and smithsonite was significantly different. Guar gum selectively adsorbed on the calcite surface and formed strong Ca-O chemical bond via phosphate group and hydroxide radical, which reduced the number of Ca adsorption sites on the calcite surface and thus hindered the interaction between sodium oleate and calcite surface, realizing the effective flotation separation of smithsonite from calcite. • GG helps achieve effective flotation separation of smithsonite. • GG selectively forms strong Ca-O bond on calcite surface. • GG adhesion on calcite surface inhibits NaOL adsorption.