Flotation separation of smithsonite from calcite using a new depressant fenugreek gum

Abstract Selective separation of smithsonite from gangue, especially calcite, remains a difficult problem in practice duo to the fact that selectivity of depressants currently used are not good. In this study, fenugreek gum (FGM) was used as a new depressant to separate smithsonite from calcite when using cationic collector octadecylamine acetate (ODA). Flotation results show that FGM can excellently separate smithsonite from calcite. The selective interaction mechanism of FGM was disclosed by zeta potential measurements, adsorption amount measurements and FTIR studies. The results of adsorption amount measurements indicate that FGM adsorbs much more on calcite than smithsonite and the interaction of FGM with calcite lowers the adsorbed amount of ODA on calcite surface. The zeta potential measurements results show that FGM hardly interferes with the surface charge of smithsonite but has conspicuous influence on that of calcite. The FTIR studies confirm the chemisorption of FGM on calcite surface and weak adsorption on smithsonite surface, possibly caused by electrostatic interaction or hydrogen bond.