Abstract: The low-grade dolomite-type fluorite ore with fluorite grade of 37% and dolomite grade of 51% was selected as the research object. Sodium humate， tannin， acidified sodium silicate and sodium fluorosilicate was used as inhibit to study its inhibition effects on various gangue minerals in run-of-mine ore at different pulp pH values and different inhibitor dosages. Through research: under acidic conditions， the inhibition of sodium humate to calcite was enhanced， the inhibition to dolomite is weakened under alkaline conditions. The inhibition of tannin to calcite is weakened under acidic conditions， the inhibition to dolomite is enhanced under alkaline conditions， and the inhibition to calcite is weakened. The acidified sodium silicate has an enhanced inhibition to the calcite and dolomite under acidic conditions， and the inhibition is weakened under alkaline conditions. The pulp pH has no effect on the inhibition of sodium fluorosilicate to dolomite， and the inhibition to calcite is enhanced under alkaline conditions. Among the four inhibitors， the inhibition of sodium humate was stronger than that of sodium fluorosilicate， followed by acidified sodium silicate， and the inhibition of tannin was the weakest. Sodium fluorosilicate has better selectivity to gangue minerals than sodium humate. The optimum conditions are: grinding fineness -0.074 mm accounted for 73%， sodium carbonate dosage 500 g/t， collector BK410 dosage 400 g/t and sodium fluorosilicate dosage 1 000 g/t， fluorite concentrate with CaF2 grade 86.23% and recovery 61.20% was obtained by being treated with opened-circuit process consisting of once roughing one scavenging two cleaning.

Key words: Fluorite, Dolomite, Calcite, Inhibitor