Mechanism of interaction between cationic surfactant and kaolinite

Abstract

The floatability of kaolinite was investigated in the presence of dodecylamine(DDA).Based on the analysis of chemical composition of each kaolinite cleavage plane and the quantum calculation of interaction between kaolinite surfaces and DDA,the interaction model under diverse pH values was constructed to explain the special flotation behavior of kaolinite in the presence of cationic surfactant.In alkaline pulp,the mineral powders can be fully dispersed in the suspension owning to negative charge held by both side and bottom surface of kaolinite crystal. The cationic surfactant DDA has the adsorption priority on the (001) surface of kaolinite resulting in the varying hydrophilic of different surfaces of kaolinite.Triggered by intensive hydrophilic force of mineral powder,hydrophobic flocculation occures, then the hydrophobic surface areas are reduced greatly and followed by the increased difficulties of mineral flotation. In acid pulp,dodecylamine can be fairly adsorbed on each surfaces of kaolinite for the similar surface properties of (001) surface and {001} resulted from the H~+ adsorption on the bottom surface. And the adsorptive density of collector is well increased for the decreased total surface areas of kaolinite powders as a result of the flocculation caused by the positive charge and the negative charge held by side and bottom surface respectively.Thus the kaolinite flotation rate could keep a relatively high level under lower pH values condition.