Effect of EDTA on quartz and hematite flotation with starch/amine in an aqueous solution containing Mn2+ ions

Deisiane Ferreira Lelis,Rosa Malena Fernandes Lima,Versiane Albis Leão

doi:10.1590/0370-44672016690014

Deisiane Ferreira Lelis, Rosa Malena Fernandes Lima + Show 1 more

Open Access

https://doi.org/10.1590/0370-44672016690014

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Abstract

In this paper, a detailed study of the influence of Mn2+ 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 Mn2+ ions is due to the following: (i) the adsorption of Mn hydroxy complexes (Mn2(OH)3+ and Mn(OH)+); (ii) Mn2+ 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 Mn2+ 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.

Highlights

Reverse cationic flotation is commonly used to concentrate the pellet feed fraction (−150 μm) of low-grade iron ores (25% to 45% Fe)
This study presents the influence of Mn2+ ions on the floatability and zeta potential values of quartz and hematite, which are the main minerals present in the iron ore previously studied by Cruz and Lima (2015), at pH 10.5 with: i) ether amine, ii) starch/ether amine and iii) chelating ethylenediaminetetraacetic acid (EDTA))/starch/ether amine
The reagents used in the microflotation tests and zeta potential measurements were as follows: i) commercial ether amine acetate with a 50% neutralization degree (Clariant A.S.) as the collector; ii) commercial corn starch (Unilever A.S.) as the depressant; iii) manganese chloride tetrahydrate (MnCl2·4H2O) (LabSynth Ltd.); iv) EDTA (C10H14N2O8Na2·2H 2O) (LabSynth Ltd.) as the complexing agent; v) sodium chloride (NaCl)

Summary

Introduction

Reverse cationic flotation is commonly used to concentrate the pellet feed fraction (−150 μm) of low-grade iron ores (25% to 45% Fe). Ζeta potential measurements of sulphide minerals (pyrite, galena, arsenopyrite) (Wang and Forssberg, 1990), and metal hydrous oxides (hematite, β-FeOOH) (Rubio and Matjevic, 1979, Chang et al 1982 ) show that in presence of EDTA, the IEP of these minerals is shifted to lower pH values, which was ascribed to specific interactions between their surfaces with complexing solute species at pH values

Mineral samples and reagents

Microflotation tests

Zeta potential measurements

Manganese species in water

Conclusions