Regulating effects of citric acid and pregelatinized starch on selective flocculation flotation of micro-fine siderite

To improve the beneficiation efficiency of carbonate-bearing iron ore, a selective-flocculation flotation method was developed to separate micro-fine siderite with citric acid and pregelatinized starch, which serve as the dispersant and the flocculant, respectively. Given that pregelatinized starch may have adverse effects on dispersion effect of citric acid, the regulating effects of these two species on the selective flocculation flotation of micro-fine siderite were examined by micro-flotation of artificially mixed ores and molecular dynamics simulations. The analyses of particle-size distribution and aggregation behaviour showed that citric acid effectively decreased the attachment of micro-fine siderite to hematite and quartz. In contrast, micro-fine siderite formed flocs selectively with pregelatinized starch. Molecular dynamics calculations revealed that citric acid and pregelatinized starch could co-adsorb on siderite. Collector molecules of sodium oleate penetrated the adsorption layer and thus were adsorbed onto siderite. However, sodium oleate was unable to penetrate the dense pregelatinized starch layer on hematite. Furthermore, both pregelatinized starch and sodium oleate were barely adsorbed onto quartz. The regulating effects of citric acid and pregelatinized starch improved the selective flocculation flotation of micro-fine siderite. The FeO content of the ore was 5.15%, and this was increased to 20.15% by the above treatment, with a recovery rate of 71.08%.