Molecular arrangement of starch, Ca2+ and oleate ions in the siderite-hematite-quartz flotation system

Based on the negative effects caused by siderite in the reverse flotation of hematite, different molecular arrangement and adsorption behaviors of flotation reagents on siderite, hematite and quartz were investigated by molecular simulations in order that the mechanism of depressant, activator and collector would be clearly understood and the adverse effects of siderite could be eliminated. Flotation results showed that both the grade and recovery of iron decreased with the increasing content of siderite and the decreasing grain sizes. Molecular arrangement of the flotation reagents in solution was visually displayed by the optimum adsorption models on different mineral surfaces. As the relative concentration shown, starch and oleate ions could be adsorbed on siderite surface which caused the mixture of concentrates and tailings. Ca2+ had little effects on siderite and hematite, but it had strongest effect on quartz. The formation of Ca(OH)+ and the connection between COO− and Ca(OH)+ made quartz be collected. But Ca2+ could not active the quartz covered by siderite. So it is essential to prevent siderite from entering the second stage of two-step flotation.