Low-alkalinity flotation separation method for pyrite activated by Cu2+ and chalcocite

The invention discloses a low-alkalinity flotation separation method for pyrite activated by Cu2+ and chalcocite. The method comprises the steps that lime is firstly added in the ore grinding stage so as to keep low alkalinity, a composition of citric acid, sodium sulfite and pyrogallic acid is added as a composite inhibitor in the rougher flotation stage to inhibit the pyrite, copper rougher flotation is achieved under the condition of low alkalinity, then a dispersing agent is added for concentration, inhibition on gangue minerals is intensified, and copper concentrates are obtained. Compared with the traditional manner of inhibiting sulfur through lime, the inhibition effect of the composite inhibitor on the pyrite activated by Cu2+ is remarkable, wherein citric acid is used for removing the activation action of Cu2+ on the pyrite, so that natural floatability of the pyrite is restored, the inhibition effect on the pyrite is intensified through sodium sulfite and pyrogallic acid, meanwhile, the phenomenon