Cextrant 230对氟碳铈矿盐酸优浸液中钍和铁的选择性去除

Selective Removal of Thorium and Iron from Selective Hydrochloric Acid Leach Solution of Bastnaesite by Solvent Extraction Using Cextrant 230

研究了(二(2-乙基己基)-(N-(2-乙基己基)胺基)甲基膦酸酯(Cextrant 230,记为L)萃取剂对氟碳铈矿盐酸优浸液中Th(Ⅳ),Fe(Ⅲ)和稀土(Ⅲ)的萃取行为。结果表明:Cextrant 230对HCl介质中的Th(Ⅳ)和Fe(Ⅲ)有良好的萃取性能,而对稀土(Ⅲ)不萃取;Cextrant 230与Th(Ⅳ),Fe(Ⅲ)的萃合物结构式分别为ThCl4·4L和HFeCl4·L;萃取过程的热力学参数结果表明,Fe(Ⅲ)的萃取反应是吸热过程,而Th(Ⅳ)的萃取不受温度影响;当水相酸度为0.28 mol·L^(-1)HCl时,0.4 mol·L^(-1)Cextrant 230萃取Th(Ⅳ)和Fe(Ⅲ)的饱和负载容量分别为0.013和0.12mol·L^(-1);负载有机相中的Th(Ⅳ)和Fe(Ⅲ)可采用水和1.0 mol·L^(-1)HNO3分步反萃;经3级错流萃取,氟碳铈矿盐酸优浸液中的Th(Ⅳ)和Fe(Ⅲ)含量明显降低,其中,Th(Ⅳ)从65 mg·L^(-1)降至0.03 mg·L^(-1),Fe(Ⅲ)从5069 mg·L^(-1)降至42.56 mg·L^(-1)。

The extraction and separation of thorium,iron and trivalent rare earths from the selective hydrochloric acid leach solution of bastnaesite using di(2-ethylhexyl)[N-(2-ethylhexyl)amino methyl]phosphonate(Cextrant 230,abbreviated as L)were investigated.Cextrant 230 can extract thorium(Ⅳ)and iron(Ⅲ)but hardly trivalent rare earths in chloride medium.The extracted complexes were determined to be ThCl4·4L and HFeCl4·L.Thermodynamic parameters(ΔH,ΔG andΔS)were calculated and the extraction of Fe(Ⅲ)by Cextrant 230 is an endothermic process,while the extraction of Th(Ⅳ)was barely affected by temperature.The loading capacities of 0.4 mol·L^(-1)Cextrant 230 for Th(Ⅳ)and Fe(Ⅲ)from chloride solutions with 0.28 mol·L^(-1)HCl were determined to be 0.013 and 0.12 mol·L^(-1),respectively.The loaded Th(Ⅳ)and Fe(Ⅲ)can be stripped and separated by 1.0 mol·L^(-1)HNO3and distilled water.By 3 stages of cross-flow extraction on the selective hydrochloric acid leach solution of bastnaesite,the concentrations of thorium and iron decrease obviously from 65 and 5069 mg·L^(-1)to 0.03 and 42.56 mg·L^(-1),respectively.