Abstract: In order to provide reference for solving the inhibition problem of calcite in non-sulphide flotation system，the depression effect and mechanism of gallic acid on calcite in sodium oleate flotation system was studied through flotation tests，collector's adsorption measurements and infrared spectroscopic analysis.The results show that calcite is significantly depressed with the addition of gallic acid of 5×10^-5 mol/L in pH range of 9~11 and the concentration of sodium oleate of 1.0×10^-4 mol/L.The depression effect originates from hydrophilic chelate on the surface of calcite，which is formed by the reaction between the two hydroxyls in gallic acid and Ca2+ on calcite surface.The formed chelate prohibits the adsorption sodium oleate on calcite surface，and generates hydrophilic membrane on calcite surface.

Key words: Gallic acid, Calcite, Flotation, Depression, Adsorption, Chelate