ABSTRACT In this work, the simultaneous effects of Ca2+ and Cl− ions in an aqueous solution at pH 10.5 on the flotation of quartz (the main impurity in itabiritic iron ore) and hematite by starch and amine was investigated. A strong depression in the flotation of both quartz and hematite conditioned with CaCl2 was observed. This effect was higher for hematite than for quartz. Based on zeta potential measurements and the speciation diagram of calcium in aqueous solutions, the physical adsorption of Ca2+ on the surfaces of both minerals was inferred. The infrared spectrum of quartz conditioned with CaCl2 at pH 10.5 was similar to its reagent-free reference spectrum. However, a new band at the wavenumber of 1465 cm−1 was identified in the spectrum of hematite conditioned with CaCl2; this band did not exist in its reference spectrum. This new band may indicate the chemical adsorption of Cl− ions on the hematite surface. The complexation of Ca2+ by ethylenediaminetetraacetic acid enabled complete quartz recovery with amine. For hematite, recovery was partially restored, probably because of the positive chloro-complexes on the hydrated iron surfaces of hematite, which prevented the adsorption of aminium ions at these sites. Therefore, the selective inverse cationic flotation of itabiritic iron ore at pH 10.5 in water containing Ca2+ is possibly only after complexing them with EDTA.

中文翻译：

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钙离子和氯离子对铁矿石反阳离子浮选的影响：基础研究

摘要 在这项工作中，研究了 pH 10.5 水溶液中 Ca2+ 和 Cl- 离子对淀粉和胺浮选石英（铁矿石中的主要杂质）和赤铁矿的同时影响。观察到用 CaCl2 调节的石英和赤铁矿的浮选效果明显下降。赤铁矿的这种影响高于石英。基于 zeta 电位测量和水溶液中钙的形态图，推断 Ca2+ 在两种矿物表面的物理吸附。在 pH 10.5 条件下用 CaCl2 调节的石英的红外光谱与其不含试剂的参考光谱相似。然而，在用 CaCl2 调节的赤铁矿光谱中，在 1465 cm-1 波数处发现了一个新谱带；该波段在其参考光谱中不存在。这个新带可能表明 Cl− 离子在赤铁矿表面的化学吸附。Ca2+ 与乙二胺四乙酸的络合使石英与胺完全回收。对于赤铁矿，回收率部分恢复，这可能是因为赤铁矿水合铁表面上的正氯络合物阻止了这些位点对铵离子的吸附。因此，在 pH 10.5 的条件下，在含有 Ca2+ 的水中选择性反阳离子浮选 itabirite 铁矿石可能只有在它们与 EDTA 络合之后才能进行。可能是因为赤铁矿水合铁表面上的正氯络合物阻止了这些位点对氨离子的吸附。因此，在 pH 10.5 的条件下，在含有 Ca2+ 的水中选择性反阳离子浮选 itabirite 铁矿石可能只有在它们与 EDTA 络合之后才能进行。可能是因为赤铁矿水合铁表面上的正氯络合物阻止了这些位点对铵离子的吸附。因此，在 pH 10.5 的条件下，在含有 Ca2+ 的水中选择性反阳离子浮选 itabirite 铁矿石可能只有在它们与 EDTA 络合之后才能进行。