Research On Electrodialysis Technology Recover Rare Earth From Leaching Liquor Of Ion-absorbed Rare Rarth

Rare earth resources are abundant in China, the ion-absorbed rare earth is peculiar rareearth mineral of China, but the extensive production, serious pollution complex and longprocess has serious implications for the development and benefit of rare earth industry. As anefficient and practical new technology, membrane technology has significant effect in terms ofmaterial liquid separation, enrichment and purification, application areas have been expanding,electrodialysis technology is one of them. This topic proposed the electrodialysis technologyused for concentrating recycle rare earth of ion-absorbed rare earth ore leachingliquid, studied the influence factors and process flow of electrodialysis technologyconcentrating ion-absorbed rare earth ore leaching liquor.The sample is leaching liquor of one ion-absorbed rare earth ore that after In-situ leachedthen used ammonium bicarbonate making the impurities to precipitate, it came from GanZhouof Jiangxi, it’s rare earth concentration is0.207g/L. In the trial test of electrodialysisconcentrated ion-absorbed rare earth leaching liquid, the rare earth ion almost migrated to theconcentrate after15minutes, which indicated that electrodialysis technology could recoverthe rare earth from leaching liquor. The test of choosing ion exchange membrane confirmedhomogeneous membrane was the most suitable for concentrating the leaching liquor ofion-absorbed rare earth. The limiting current test got the limit current in different materialconcentration and operating conditions, and analyzed some factors’ effect on electrodialysisconcentrate the leaching liquor of ion-absorbed rare earth, such as working current, materialflow, rare earth concentration ratio of material, the best operation condition was work currentas high as possible in case of under the limit current value, thick and thin material flow was20L/h, equal initial rare earth concentration. The whole process test of electrodialysiscircularly recover the rare earth was done under the conditions of5V voltage and materialflow20L/h, after six times circular concentration, the final concentrate’s rare earthconcentration could reach4.532g/L, the desalination solution’s rare earth concentration is0.004g/L, the recovery of rare earth is75.47%. In addition, the other component includingammonia of the leaching liquor are also migrated to concentrate, it’s ammonia concentrationis5507.4mg/L, it could be recovered by directly evaporative crystallization.Membrane fouling has a great influence on electrodialysis recover rare earth. The main reasons for ion exchange membrane fouling during electrodialysis concentrate the leachingliquor of ion-absorbed rare earth are the polarization in the Electordialyzer and some ionssupersaturate in concentrate compartments, both of them easy to precipitate. Membranefouling can not completely avoid, it could be controlled to some extent by pretreating the rawwater, using pluse current and optimizing operation process. When the membranes arepolluted, uses5%citric acid circular cleaning for10minutes, the flow could recover,permeability recover to more than90%of the initial value.