Solvent extraction and separation of light rare earths from chloride media using HDEHP-P350 system

• 作者: Wenjie Zhang Dongxia Feng Xian Xie Xiong Tong Yunpeng Du Yang Cao
• 来源期刊: 稀土学报（英文版）
• 年，卷（期）: 2022,（2）
• 所属期刊栏目: CHEMISTRY AND HYDROMETALLURGY
• 页码范围: 328-337
• 页数: 10页
• 语种: 英文

摘要

Solvent extraction is the most important method for rare earth extraction and separation.Currently,di(2-ethylhexyl) phosphoric acid (HDEHP) and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEH/EHP) are widely used in industrial production,but there are still obvious deficiencies that require further research to resolve.In this paper,the unsaponification extraction of light rare earth ions in a hydrochloric acid medium by di(2-ethylhexyl) phosphoric acid-di(1-methyl-heptyl) methyl phosphonate (HDEHP-P350) system was studied.The results show that the addition of P350 reduces the extraction capacity of HDEHP,and also greatly reduces the concentration of acidity required for the back-extraction.It still has a good separation factor for light rare earths without saponification,and the extractant is not easy to emulsify.With an aqueous phase of pH =2.85,and HDEHP mole fraction XHDEHP =0.9 (compared with O/A-2),the separation effect of light rare earth is the best,resulting in the separation coefficient βCe/La =3.39,βPr/Ce =1.67 and βNd/Pr =1.45,respectively.The loaded light rare earth ions extracted by HDEHP-P350 can be easily stripped when 2 mol/L HCl is used as the stripping agent.Finally,the extraction mechanism is discussed using a slope method,and the final structure of the extracted com-plex is determined to be RECl[(DEHP)2]2P350(o),based on a combination of infrared spectra and 1H NMR and 31p NMR analyses.