| Summary: | The floatability of scheelite and calcite in the presence of single depressant (SHMP or H<sub>3</sub>Cit) and mixed depressant (SHMP/H<sub>3</sub>Cit) was studied by microflotation experiments and artificial mixed mineral experiments. Solution chemical calculation, zeta potential tests, thermodynamic analysis and XPS analysis were used to explain the relevant depressive mechanism. Mixed depressant (SHMP/H<sub>3</sub>Cit) exhibited excellent selective depressive effect on calcite. The optimal molar ratio of SHMP to H<sub>3</sub>Cit was 1:4. The depressant SHMP and H<sub>3</sub>Cit can be chemically bonded with Ca<sup>2+</sup> to form CaHPO<sub>4</sub> and Ca<sub>3</sub>(Cit)<sub>2</sub> at pH 8. The CaHPO<sub>4</sub> was more easily formed than Ca<sub>3</sub>(Cit)<sub>2</sub> on the mineral surface, which indicated that the depressive effect of SHMP was stronger than H<sub>3</sub>Cit. The SHMP and H<sub>3</sub>Cit of the mixed depressant were co-adsorbed on the calcite surface, while the H<sub>3</sub>Cit of the mixed depressant was weakly adsorbed on the scheelite surface. The mixed depressant can significantly improve the separation efficiency of scheelite from calcite.
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