The flotation separation of molybdenite from talc using zinc sulfate in sodium silicate system and related mechanism

The function of sodium silicate is similar to that of sodium carbonate in flotation processes. In particular, in the presence of many different kinds of silicate gangue in minerals, sodium silicate performs better than sodium carbonate in inhibiting gangue formation by flotation. The results of this study showed that sodium silicate can replace sodium carbonate and inhibit talc flotation in combination with zinc sulfate; the associated depression mechanism was also investigated. The flotation results demonstrated that sodium silicate had a certain depressing effect on talc flotation compared with molybdenite, and that zinc sulfate could selectively inhibit talc flotation at pH ~10 in the sodium silicate system. Contact angle measurements further confirmed that the hydrophobicity of talc decreases upon the addition of zinc sulfate to the sodium silicate system. Fourier-transform infrared spectroscopy and zeta potential analysis provided strong evidence that zinc sulfate and sodium silicate underwent physical adsorption on talc surfaces. Additionally, zeta potential analysis, solution chemical analysis, and time-of-flight secondary ion mass spectrometry showed that sodium silicate may be hydrolyzed to form silicic acid micelles, which formed metal cation complexes with zinc sulfate and were intertwined and physically adsorbed on the talc surface.