金属阳离子在锂辉石浮选中的活化行为及作用机理

在油酸浮选锂辉石体系中分别加入Ca^2+、Al^3+、Fe^3+离子,通过单矿物浮选试验、金属离子吸附量检测、金属离子水解组份浓度计算、矿物表面动电位测试、红外光谱检测以及量子化学模拟计算研究Ca^2+、Al^3+、Fe^3+离子对锂辉石浮选的活化行为和作用机理。结果表明:Ca^2+离子的最佳活化区间为pH大于12的强碱性条件,Al^3+离子的最佳活化pH为6.47,而Fe^3+离子的最佳活化pH为7.25;在这些pH区间内,锂辉石浮选回收率和金属离子吸附量均达到最大值。在锂辉石浮选过程中起活化作用的有效组份为它们分别对应的氢氧化物沉淀。Ca^2+、Al^3+、Fe^3+离子可使锂辉石表面动电位向正值方向显著偏移;Ca^2+离子在锂辉石表面双电层的外层发生静电吸附,Al^3+和Fe^3+离子在锂辉石表面双电层的内层发生特性吸附。钙原子与锂辉石矿物表面吸附后形成的Ca—O键的键强较小,以离子键为主;铁原子与矿物表面形成Fe—O化学键的键强较大,含有一定的共价键组份;而铝原子与矿物表面吸附后形成的Al—O键的键长、键强等参数介于钙、铁的参数之间。油酸在Ca^2+活化后的锂辉石表面发生了化学吸附和少量的物理吸附,而在Al^3+、Fe^3+活化后的锂辉石表面发生了较为强烈的化学吸附。

Activation behavior and mechanism of metallic cations in spodumene flotation

Ca^2+,Al^3+,Fe^3+ions were added as activator into spodumene flotation system using collector of oleic acid.The activation performance and mechanism of Ca^2+,Al^3+,Fe^3+ions on spodumene flotation were investigated by single mineral flotation experiments,metal ion adsorption detection,calculation of solution chemistry of metal ions,zeta potential measurements,infrared spectroscopy analysis and quantum chemical simulation calculation.The results show that the optimum activation range of Ca^2+is in strong alkaline condition with pH greater than 12,the optimum activation pH of Al^3+is 6.47,and the optimum activation pH of Fe^3+is 7.25.Within these pH ranges,the recovery of spodumene flotation and the adsorption capacity of metal ions reach the maximum value.The dominant active components are hydroxide precipitation of Ca^2+,Al^3+,Fe^3+ions accordingly.The ions can make the surface potential of spodumene shift significantly to the positive direction.Ca^2+ions are adsorbed on the outer layer of the electric double layer on the surface of spodumene by electrostatic adsorption,while Al^3+and Fe^3+ions are adsorbed on the inner layer of the electric double layer by specific adsorption.Ca—O bonds formed by the adsorption of calcium atoms on the surface of spodumene minerals are weak,mainly in the form of ion bonds.The bond strength of Fe—O bonds is strong and contained certain covalent bond components,while the bond length and bond strength of Al—O bonds formed by adsorption of Al atom on mineral surface are between those of Ca and Fe.It is chemical and faint physical reaction by which oleic acid is adsorbed on the Ca^2+activating spodumene surface,and the strong chemical adsorption occurs on the surface of spodumene activated by Al^3+and Fe^3+.