Abstract: Talc easily is reported to reduce concentrate grade as a common gangue mineral in complex sulphide ores.The influences and mechanism of several metal ions(Ca²⁺、Mg²⁺、Cu²⁺、Fe³⁺) on the flotation of talc were investigated by flotation experiments of single talc，measurements of Zeta potential and induction time，calculation of solution chemistry and electrostatic interactions.The results show that Ca²⁺，Mg²⁺，Cu²⁺and Fe³⁺ can adsorb on the surface of talc.Ion like Ca²⁺shows no significant influence and Mg²⁺can depress flotation of talc at higher pH values (pH＞10).Flotation of talc can be depressed at pH 4~10 while adding Cu²⁺ and the inhibition is strongest when pH=6.Similarly，flotation of talc can be depressed at pH 3~9 while adding Fe³⁺ and the inhibition is strongest when pH=7.Solution chemistry calculations confirm that the Zeta potential of talc can be changed through the adsorption of metal ion complexes onto the surfaces of talc and the recovery of talc decreases due to precipitation of hydroxide.The calculations of electrostatic interactions indicate the hydrophobic surfaces of talc become hydrophilic and talc flotation is depressed within certain pH range due to hetero-coagulation of the metal hydroxides on surfaces of talc.The flotation recovery of talc can rise again when pH＞PZC of metal hydroxides.The experiments play an instructive role for depressing and separation talc from sulphide ores contain talc.

Key words: Talc, Metal ions, Flotation, Depression, Adsorption