Abstract: The effect of five combined compressors, namely Na₂S₂O₃+ pyrogallic acid, NaClO+ pyrogallic acid, CaCl₂+tannic acid, KMnO₄+tannic acid and NaClO+ sodium humate, on the floatability of chalcopyrite and pyrite at low basicity of pH=8 were studied. The results showed that all of them can be used as the selective depressor of pyrite in the flotation for separating copper from sulfur but are different in the selectivity and dosage. With the combination of NaClO+ sodium humate as example, the pyrite depression effects of combined depressor and single depressor were compared and the result proved that the combined depressor has a better effect. Finally, the depression mechanism of NaClO+ sodium humate for pyrite was studied by infrared spectroscopic analysis.

Key words: Combined depressor, Chalcopyrite, Pyrite, Flotability