In order to improve the flotation recovery of fine kaolinite, mixed dodecylamine chloride/fatty acid was used as collector in kaolinite flotation process. The performance of dodecylamine chloride/fatty acid mixture collector on kaolinite flotation was investigated using flotation test and computational method. Surface tension measurement, contact angle measurement and image analysis were also used to study the flotation behavior of dodecylamine chloride and mixture collectors. The flotation results showed that much higher kaolinite flotation recovery was obtained in the presence of dodecylamine chloride/octanoic acid mixture compared with that in the presence of dodecylamine chloride alone. Surface tension measurements indicated that the mixed dodecylamine chloride/octanoic acid collector was more efficient at decreasing the air water interfacial tension. Molecular dynamics simulation showed that the octanoic acid molecules were interleaved among dodecylamine chloride ions and co -adsorbed at the kaolinite (001) surface. The relative concentration of water molecules near kaolinite (001) surface further decreased in the presence of dodecylamine chloride/octanoic acid compared with that in the presence of dodecylamine chloride alone, which indicated a much stronger hydrophobicity of the kaolinite (001) surface. (C) 2017 Elsevier B.V. All rights reserved.