Rare earth element is an important strategic metal, but the supply of high purity rare earth ores is growing slowly, which is in sharp contradiction with the rapidly growing demand. Froth flotation has been confirmed to be an effective method to separate bastnaesite from its gangue minerls. However, the traditional collectors are facing serious problems in flotation separation of minerals, requiring the addition of excess depressant and regulator in the flotation process. Herein, we proposed and synthesized novel Gemini hydroxamic acids Octyl-bishydroxamic acid (OTBHA), Decyl-bishydroxamic acid (DCBHA) and Dodecyl-bishydroxamic acid (DDBHA) as the collectors in bastnaesite-barite flotation system. The effect of different carbon chain lengths on the molecular properties were explored by density functional theory (DFT) calculations. DCBHA possessed a stronger reactivity compared with OCBHA and DDBHA. The flotation results verified the consistency of the computational calculation about the performance prediction of Gemini hydroxamic acids. Compared with OCBHA and DDBHA, DCBHA displayed superior collecting affinity toward bastnaesite, and did not float barite. Zeta potential results showed that the presence of DCBHA increased the potential of bastnaesite, while it had almost no effect on barite, indicating DCBHA had a stronger affinity for bastnaesite. Then, Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that the adsorption mechanism was due to two hydroxamate groups of DCBHA co-anchored on bastnaesite surface by forming five-membered hydroxamic―(O―O)―Ce complexes. In addition, atomic force microscopy (AFM) clearly observed that DCBHA uniformly aggregated on bastnaesite surface, which increased surface contact angle and improved the hydrophobicity of bastnaesite.

稀土元素是重要的战略金属，但高纯稀土矿供应增长缓慢，与快速增长的需求形成鲜明矛盾。泡沫浮选已被证实是从脉石矿物中分离氟碳铈矿的有效方法。然而，传统捕收剂在矿物浮选分离中面临着严重的问题，需要在浮选过程中添加过量的抑制剂和调节剂。在此，我们提出并合成了新型Gemini异羟肟酸，辛基双异羟肟酸（OTBHA）、癸基双异羟肟酸（DCBHA）和十二烷基双异羟肟酸（DDBHA）作为氟碳铈矿-重晶石浮选体系的捕收剂。通过密度泛函理论（DFT）计算探讨了不同碳链长度对分子性质的影响。与OCBHA和DDBHA相比，DCBHA具有更强的反应活性。浮选结果验证了Gemini异羟肟酸性能预测的计算结果的一致性。与OCBHA和DDBHA相比，DCBHA对氟碳铈矿表现出优异的捕收亲和力，并且不会浮选重晶石。Zeta电位结果表明，DCBHA的存在增加了氟碳铈矿的电位，而对重晶石几乎没有影响，表明DCBHA对氟碳铈矿有更强的亲和力。然后，傅里叶变换红外（FTIR）和X射线光电子能谱（XPS）分析表明，吸附机理是由于DCBHA的两个异羟肟酸基团通过形成五元异羟肟酸—（O—O）—共同锚定在氟碳铈矿表面上。 Ce配合物。此外，原子力显微镜（AFM）清晰地观察到DCBHA均匀聚集在氟碳铈矿表面，增大了表面接触角，提高了氟碳铈矿的疏水性。