Abstract: The influences of metal ions on floatability of kyanite， quartz and biotite were studied by flotation tests. The test results showed that Ca²⁺ and Mg²⁺ have significant activation of kyanite flotation， while Al³⁺ and Fe³⁺ have strong depression of quartz and kyanite flotation. The analysis results of flotation solution chemistry showed that the flotation of kyanite and quartz are depressed intensively owing to the generation of corresponding hydroxide precipitations of A1³⁺ and Fe³⁺. The electrostatic interaction is contributing to strengthen the adsorption of minerals and dodecylamine when the zeta potential of kyanite shift markedly towards negative direction in the presence of corresponding hydroxy complex of Ca²⁺ and Mg²⁺， so flotation of kyanite can be activated. According to particle distribution theory in Boltzmann vector field， activation or depression mechanism of metal ions were analyzed by calculating amine ion(RNH⁺₃) concentration in liquid phase interior， the interface layer and their ratio under different pH value conditions before and after Fe⁺₃ effect on minerals.

Key words: metal ions, kyanite, quartz, biotite, flotation, solution chemistry