Improvement Effect of FeSO·7HO on Flotation Separation of Scheelite from Fluorite.

In this study, FeSO·7HO 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 FeSO·7HO and subsequent addition of sodium silicate (SS) resulted in a stronger selective depression effect on fluorite compared with SS alone. Addition of FeSO·7HO reduced the required dosage of SS and had little negative effects on scheelite recovery. The selective depression mechanism of FeSO·7HO 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.