Effect of Ultrasonication on the Flotation of Talc

The natural hydrophobicity of talc was depressed by the use of ultrasonic treatment during flotation. The recovery of the talc decreased by nearly 30% after 4 min of ultrasonic preconditioning. In addition, two talc depressants, namely, IMP4 and carboxymethyl cellulose (CMC), were compared during ultrasound treatment. The guar gum IMP4 showed a better depressant ability than the CMC. The effects of these depressants on talc were enhanced by ultrasonication, preferably by adding the depressants before ultrasonic treatment. Microtopographic studies by atomic force microscopy indicated that surface defects generated by ultrasound could serve as active sites for water adsorption, rendering the naturally hydrophobic talc hydrophilic. The enhanced formation of the hydrophilic magnesium and silicon hydroxyl species on talc surfaces slightly affected the natural hydrophobicity of talc in the presence of ultrasound as well.