Abstract: This paper analyzed the relationship of the surface electricity of iron concentrate and silicate minerals with pH values of ore pulp, and the hydrolysis behavior of amine collector in ore pulps.On this basis, experiment is made to research the mechanism of amine collector in reverse flotation de-silicates process of iron concentrates.The results showed that the amine-collector in RNH₂ does not act with the silicate minerals and could not reduce silicon under strong alkaline; Under strong acid condition, high content of amine-cation (RNH⁺₃) in ore pulps acting with each other reduce or even lose the adsorption on mineral particles, and can not reach the good separation effect either.Hence, in reverse flotation de-silicates process of iron concentrates, an appropriate amine-action concentration should be kept by adjusting the  pH values according to the ore property.

Key words: Iron concentrate, Reverse flotation de-silicates, Amine-collector, Mechanism