Study On Technology Of Refined Rare Earth Gadolinium Removal Of Alumium By Ionic Liquid Method

With the rapid development of high-tech industry,the demand of high purity gadolinium is increasing in the fields of biomedicine,electronics and nuclear energy,and the rare earth gadolinium aluminum removal technology has become a research hotspot.However,it is difficult to separate and remove aluminum from the gadolinium solution because of its special occurrence state and amphoteric characteristics.The conventional solvent extraction technology for aluminum removal has the disadvantages of easy emulsification of extractant,high pollution in the process and low overall efficiency,which make it difficult to meet the requirements of preparing high-purity rare earth gadolinium.Ionic liquids are considered as green and efficient rare earth metal extractants with great potential to replace organic molecular solvents due to their design-able structure and easy performance regulation.Based on this,two functional ionic liquids[N1888][CA12]and[N1888][NA]were synthesized in this study.The extraction conditions of aluminum removal were optimized,the extraction mechanism was analyzed,the ionic liquid[N1888][CA12]was prepared on a large scale,and the continuous and stable cascade aluminum removal evaluation experiment was carried out.The main research contents are given as follows:(1)A carboxylic acid functional ionic liquid[N1888][CA12]was synthesized.The effects of different time,temperature,p H,concentration and comparison of salting out agent on the extraction efficiency of Al³⁺and Gd³⁺were investigated,and the stripping conditions were optimized.The results showed that in hydrochloric acid system,when the temperature is 25?,the equilibrium time is 20 minutes,the p H value is 3.2,the salting out agent is 1 mol/L Na Cl,the ratio of O/A is 1:1,the separation coefficient?_Al/Gd of[N1888][CA12]-n-heptane system for Al/Gd can reach 15.35.Combined slope analysis method with infrared spectrum analysis,it was confirmed that the mechanism of extraction of Al³⁺and Gd³⁺by[N1888][CA12]extractant is the ion complexation mechanism.The synthesis method of ionic liquid with good comprehensive performance for aluminum removal and the basic process data of continuous amplification were obtained.(2)A carboxylic acid functional ionic liquid[N1888][NA]was synthesized.The effects of H⁺concentration and Cl^-concentration on the extraction performance of[N1888][NA]-kerosene system were investigated,and the separation performance of Al/Gd by saponifiable/unsaponifiable naphthenic acid system and[N1888][NA]system were compared.The results showed that the lower the H⁺concentration in aqueous phase,the higher the Cl^-concentration,and the higher the extraction rate of Al³⁺by[N1888][NA]system.The extraction efficiency of[N1888][NA]system was similar to that of saponified NA system.The separation coefficient of Al/Gd of[N1888][NA]system was 21.74,which was much higher than that of the latter(1.35).The analysis of extraction mechanism show that the mechanism of[N1888][NA]extractant extraction of aluminum ions is ion complexation mechanism.(3)Based on the above research results,[N1888][CA12]was prepared on a large scale.The synthesis process and comprehensive extraction performance of[N1888][CA12]were compared with that of ethanol-water as solvent and kerosene-water as solvent.The results show that the comprehensive extraction performance of[N1888][CA12]prepared is basically similar to that of the small test synthesis,and different solvents have little effect on the extraction performance of the synthesized[N1888][CA12].After 5 stages of continuous extraction,the aluminum content of the aluminium-containing rare earth feed liquid can be reduced to less than 50 ppm,and the loss rate of the ionic liquid in the whole cycle is less than 0.2%.Through economic analysis,it was found that[N1888][CA12]extraction method can save more costs in aluminum removal compared with oxalic acid precipitation method.The technological conditions of rare earth gadolinium removal by ionic liquid method were obtained,which provided technical data for industrialization.