Improvement Effect of FeSO4•7H2O on Flotation Separation of Scheelite from Fluorite

In this study, FeSO4 center dot 7H(2)O was used as an auxiliary depressant to improve the selective depression effect on fluorite. Microflotation tests using oleic acid as the collector showed that the pre-addition of FeSO4 center dot 7H(2)O and subsequent addition of sodium silicate (SS) resulted in a stronger selective depression effect on fluorite compared with SS alone. Addition of FeSO4 center dot 7H(2)O reduced the required dosage of SS and had little negative effects on scheelite recovery. The selective depression mechanism of FeSO4 center dot 7H(2)O was investigated in detail. X-ray photoelectron spectroscopy indicated that the difference in the number of surface active sites was the mechanism for improved differential flotation of scheelite from fluorite. The improved depression of fluorite was attributed to both ferrous and sulphate ions. The pre-adsorption of ferrous species increased the number of active sites, enhancing the adsorption of silicate species on the fluorite surface. Simultaneously, sulfate ions were selectively adsorbed on the fluorite surface to form hydrophilic calcium sulfate, reducing the floatability of fluorite.