The flotation separation of sphalerite from pyrite through a novel flotation reagent system of FeCl3-CuSO4-aminotriazolethione

To reduce the consumption of lime in mineral processing means reducing CO2 emission. Herein, a novel FeCl3-CuSO4-APTT (4-amino-5-pentyl-1,2,4-triazole-3-thione) approach was first developed to replace the common CaO-CuSO4-xanthate technology during flotation separation of sphalerite from pyrite. APTT exhibited a stronger collecting power towards pyrite than sphalerite, while the attendance of ferric chloride significantly depressed the floatability of pyrite and sphalerite, and its inhibition against pyrite was stronger than that to sphalerite. The addition of cupric sulfate not only removed the inhibition of ferric chloride against sphalerite, but also promoted its floatability. Nevertheless, the floatability of the FeCl3-depressed pyrite was hardly recovered by cupric sulfate. Using FeCl3 as the depressor against pyrite and CuSO4 as the activator for sphalerite, APTT realized a selective and efficient flotation recovery of sphalerite from pyrite in the weakly-acidic medium. FTIR (Fourier Transform Infrared Spectroscopy) and contact angle indicated that the pretreatment with FeCl3 and CuSO4 in sequence significantly weakened APTT adsorption on pyrite, while benefited sphalerite adsorption towards APTT, resulting in creating a dramatical difference of surface hydrophobicity and flotation recovery between the two minerals. XPS (X-ray photoelectron spectroscopy) elucidated that after modifying sphalerite surface successively through FeCl3, CuSO4 and APTT, the Cu-APTT complexes were detected on sphalerite, which were of significance to hydrophobizing its flotation.