Water structure is the most important parameter that influences the flotation of soluble salts. In this paper bubble attachment time measurements and FTIR analyses were performed to investigate the effect of water structure on the flotation behavior of sylvite (KCl), bischofite (MgCl2 center dot 6H(2)O) and carnallite (KMgCl3 center dot 6H(2)O). The results from bubble attachment time measurements suggest that collector adsorption at the surface of KCl induces flotation with either the cationic collector, ODA. or anionic collector, SDS. In contrast bubble attachment did not occur for bischofite (MgCl2 center dot 6H(2)O) or carnallite (KMgCl3 center dot 6H(2)O). Results show that the surface charge is not a determining factor in the flotation of soluble salts. Further, the interaction between water molecules and the three chloride salts dissolved in aqueous solution were studied by measuring the shift in the hydrogen-bonding of water molecules. The results indicate that KCl is a structure breaker salt, while MgCl2 center dot 6H(2)O and KMgCl3 center dot 6H(2)O are structure maker salts. Viscosities for the brines of these three salts were determined. The results give additional evidence of differences in water structure and are in good agreement with the FTIR and bubble attachment results. The findings provide further evidence that water structure plays an important role in the flotation of soluble salts. (C) 2010 Elsevier Ltd. All rights reserved.