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In this paper, a detailed study of the influence of Mn 2+ ions on quartz and hematite flotation (at pH 10.5 with starch/amine as depressor/collector) in the absence and presence of ethylenediaminetetraacetic acid (EDTA) is presented. By using zeta potential measurement and a careful analysis of manganese species present in water for dosages in which manganese hydroxide precipitated, we confirmed that the depression of both minerals by Mn 2+ ions is due to the following: (i) the adsorption of Mn hydroxy complexes (Mn 2 (OH) 3+ and Mn(OH) +); (ii) Mn 2+ and mainly (iii) the precipitation of Mn(OH) 2 on mineral surfaces. These effects hindered the adsorption of amine species on the surfaces of the minerals (quartz and hematite). EDTA was used to complex Mn 2+ to restore the recoveries of both minerals. This was confirmed by the species distribution diagrams of Mn and EDTA-Mn in water. Conditioning with starch followed by amine at pH 10.5 enabled a selective separation of these minerals.

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