Effect of dolomite on cationic reverse flotation of iron ore with amide-amine

Abstract

The reverse cationic flotation of siliceous iron ore containing dolomite is a current challenge in some mines of the Quadrilátero Ferrífero - Brazil, since the starch adsorbs on sites containing Ca and Mg species, previously adsorbed and/or precipitated on the quartz surface, thus preventing the adsorption of the collector (amine), and consequently, affecting the selectivity in the separation between quartz and iron bearing minerals. In previous studies on flotation of siliceous iron ore, using new amide-amine (pKa = 8.2) collector, selectivity was obtained in the process without the use of starch. In this work, the influence of Ca and Mg ions, added as CaCl2 and MgCl2, on the surface properties of quartz and hematite in pH 8 and 10.5, using amide-amine with and without the use of starch, as well as the effect of the collector and depressant on the surface properties of dolomite was evaluated. In bench scale flotation tests with an artificial siliceous iron ore sample containing dolomite (2.5%), it was found that starch (200 g/t) was required for the effective flotation of the ore at pH 8, which produced concentrate with 55% Fe, 25% SiO2 and 17.5% Fe in the tailing with 50 g/t of collector.