In this study, the recovery of kaolinite particles in copper and gold flotation using fresh water and sea water was investigated. Cryo-SEM analyses together with settling tests were employed to examine the formation of kaolinite network structures and its correlation with the entrainment of kaolinite particles. It was found that kaolinite had a negative effect on copper and gold grades of flotation concentrates in fresh water due to the aggregation of clay platelets in the pulp and the transport of clay aggregates into the froth. Sea water modified the association of kaolinite platelets with the formation of cross-linked network structures exacerbating the entrainment, and copper and gold grades. In addition to the compression of the double layer, the adsorption of cations on the clay platelets may also facilitate the formation of network structures in sea water. (C) 2015 Elsevier B.V. All rights reserved.