Effective flotation separation of fluorite and calcite is a critical challenge due to their comparable physicochemical characteristics and surface iso-transformation. The effects of sodium silicate (SS) and Al3+ on the flotation separation of homogenized fluorite and calcite were investigated based on flotation experiments and various measurements such as Zeta potential, scanning electron microscopy (SEM), solution chemistry, X-ray photoelectron spectroscopy (XPS), microcalorimetry. The results showed that the combination of SS and Al3+ significantly depressed calcite flotation, but only slightly affecting fluorite flotation. The surface potential of calcite was found to be increased in the presence of Al3+, enhancing the adsorption of SS. A higher affinity for the formation and adsorption of aluminum oxide on the surface of calcite compared to fluorite was indicated by SEM results, increasing the selective depression of SS on calcite. The DFT findings verified the formation of Al − O bonds upon the interaction between Al3+ and calcite. However, no Al − O bonds occurred on fluorite surface. The distinct adsorption energies were attributed to variations in the surface bonding characteristics of Al3+ with O on the calcite and F− on the fluorite. The microcalorimetry analyses revealed that the adsorption of Al3+ on calcite surface exhibited more negative adsorption enthalpy and faster adsorption kinetics, improving the adsorption of SS species on calcite surface, ultimately reducing the floatability of calcite.

中文翻译：

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使用硅酸钠和 AlCl3 作为复合抑制剂对均质萤石和方解石进行浮选分离


萤石和方解石的有效浮选分离是一项关键挑战，因为它们的物理化学特性和表面等变换相似。通过浮选实验和 Zeta 电位、扫描电子显微镜 （SEM）、溶液化学、X 射线光电子能谱 （XPS）、微量热法等各种测量，研究了硅酸钠 （SS） 和 Al3+ 对均质萤石和方解石浮选分离的影响。结果表明，SS 和 Al3+ 的组合显著抑制了方解石浮选，但对萤石浮选的影响很小。发现在 Al3+ 存在下方解石的表面电位增加，增强了 SS 的吸附。SEM 结果表明，与萤石相比，SS 对方解石表面氧化铝的形成和吸附具有更高的亲和力，增加了 SS 在方解石上的选择性抑制。DFT 研究结果证实了 Al3+ 和方解石相互作用时 Al − O 键的形成。然而，萤石表面没有出现 Al − O 键。不同的吸附能归因于 Al3+ 与方解石上的 O 和萤石上的 F− 的表面结合特性的变化。微量热分析表明，Al3+ 在方解石表面的吸附表现出更多的负吸附焓和更快的吸附动力学，提高了 SS 物种在方解石表面的吸附，最终降低了方解石的可浮性。