十二胺体系中铁离子对霓石浮选的影响及其作用机理

以十二胺(DDA)为捕收剂，通过单矿物浮选实验考察了不同矿浆pH值和铁离子浓度下霓石的浮选行为，利用人工混合矿浮选实验研究了铁离子对霓石?镜铁矿分离效果的影响。结合Zeta电位检测、Fe3+水解组分浓度计算、玻尔兹曼理论分析和分子动力学模拟研究了在DDA体系中铁离子对霓石的抑制机理。结果表明，铁离子对霓石的可浮性抑制作用较大，在pH=6.8及DDA浓度3.6×10?4 mol/L、无铁离子条件下，霓石回收率高达75.72%，溶液中铁离子浓度为3.0×10?4 mol/L时，霓石回收率仅为25.32%，同时人工混合矿浮选泡沫产品中铁品位由34.20%降低至28.71%，回收率由33.29%降低至18.35%。pH=3~11时，铁离子以荷正电的羟基络合物沉淀形式吸附在霓石表面，增大了霓石的亲水性，降低了霓石的可浮性，铁离子在霓石表面吸附使霓石零电点由2.14增至6.70，表面正电性增大减弱了阳离子捕收剂DDA与霓石表面的静电吸附，使霓石界面层内的RNH3+浓度小于界面层外，DDA吸附层松散程度增大，霓石(110)面法线方向DDA浓度分布向正方向偏移，造成霓石可浮性下降。

The effect and mechanism of iron ion on flotation of aegirite in dodecylamine system

Flotation behavior of aegirite was investigated by single mineral flotation tests at different pH values and Fe3+ concentrations which dodecylamine (DDA) was used as the collector. The effect of iron ion on the separation behavior of aegirite and specularite was studied by using artificial mixed minerals flotation. Zeta potential measurement, hydrolysis component concentration calculation of iron ion, Boltzmann theory analysis, and molecular dynamics simulation were conducted to study the depression mechanism of iron ions on aegirite in dodecylamine system. The results indicated that iron ions could depress aegirite in great extent. When the initial pH value was 6.8, and concentration of collector dodecylamine was 3.6×10?4 mol/L, the recovery rate of aegirite was 75.72%, while the recovery rate decreased to 25.32% with 3.0×10?4 mol/L iron ions in the pulp. The iron grade of froth product of artificial mixed minerals flotation decreased from 34.20% to 28.71%, while the recovery rate of iron declined from 33.29% to 18.35%. Iron ions adsorbed on the surface of aegirite in the form of hydrophilic hydroxyl complexes precipitates in the experiment range pH=3?11, which increased the hydrophilicity of aegirite and decreased its floatability. The adsorption of iron ion on aegirite surface shifted the point of zero charge from 2.14 to 6.70, which increased the surface electropositivity of aegirite and weakens the electrostatic adsorption between dodecylamine and aegirite, leading to the decrease of the RNH3+ concentration in interfacial layer of aegirite. The existence of iron ions resulted in the looser structure of the DDA adsorption layer and the shift of DDA concentration profile in the normal direction of aegirite (110) surface to the positive direction which decreased the floatability of aegirite. The results of the research improved better understanding of the role of metal ion in mineral flotation.