Environment-friendly high-purity cerium dioxide extraction method

Abstract

The invention belongs to the technical field of separation and purification of rare earth, and particularly relates to an environment-friendly high-purity cerium dioxide extraction method. The methodcomprises the following steps: (1) extracting: mixing a cerium chloride material liquid and an extracting agent at the volume ratio of 1:(1.2-1.5), extracting, separating, adding hydrotalcite whose weight is 4-6% of the weight of the extracting agent at the same time, conducting ultrasonic dispersion for 20-30 minutes, leaving to stand, then separating, recycling a solid phase, inputting an organic phase into a reextraction procedure; (2) reextracting: taking an oxalic acid solution, wherein the volume of the oxalic acid solution is 1.5-2.0 times the volume of the organic phase, reextracting at the temperature of 50-60 DEG C, conducting ultrasonic dispersion for 20-30 minutes, filtering to obtain a precipitate; (3) oxidizing: firing and oxidizing the obtained precipitate at the temperatureof 1000-1100 DEG C for 12-15 hours, and obtaining the high-purity cerium dioxide. The method abandons the traditional alkaline saponification causing serious ammonia nitrogen pollution, and the artificial hydrotalcite is used to implement ion exchange in the extraction process, so that the balanced acidity of the system is maintained, and the environmental pollution is reduced.

Description

technical field [0001] The invention belongs to the technical field of rare earth separation and purification, and in particular relates to an environment-friendly extraction method of high-purity ceria. Background technique [0002] Rare earth element (rare earth element) is the general term for 17 elements of scandium, yttrium, and lanthanide in group IIIB of the periodic table of elements, mainly in the form of single minerals. There are more than 250 kinds of industrial minerals that are suitable for current dressing and smelting conditions. There are only more than 10 species. China's rare earth resources account for 41.36% of the world's total, and it is a veritable country with rare earth resources, which has laid a solid foundation for the development of China's rare earth industry. Traditional rare earth separation methods include fractional crystallization, ion exchange, and solvent extraction, but now solvent extraction is the main method for rare earth separatio...

AI Technical Summary

Problems solved by technology

The fractional crystallization method uses oxidation or reduction reactions to precipitate step by step, which requires lengthy and complicated crystallization steps, which is not conducive to the production of large amounts of rare earths; the ion exchange method is only suitable for rare earth solutions with low solubility

The characteristics of solvent extraction technology: simple equipment, simple and fast operation, high recovery rate, good purity, good selectivity, wide range of applications; in addition to being used for separation, it can also be used as a means of concentration. The disadvantage of this method is that the toxicity of the organic solvent is high, and the multi-stage extraction operation is time-consuming, troublesome and intensive; some reagents are expensive and the cost is high

[0003] At present, the most widely used extractant in industry is acidic extractant, such as P204, P507, Cyanex272 and naphthenic acid and other organic reagents, and requires extraction and separation under low acidity conditions, and its extraction capacity is inversely proportional to the equilibrium acidity of the water phase. Generally, to extract a rare earth ion, three hydrogen ions need to be replaced into the water phase, which increases the acidity of the water phase and affects the continuous extraction. Therefore, the extraction agent must be saponified with ammonia water or sodium hydroxide lye to remove the hydrogen ions, and then Then exchange and extract with rare earth material liquid

However, the saponification process not only consumes a large amount of alkaline substances, resulting in an increase in production costs, but also produces a large amount of ammonia nitrogen wastewater, causing serious pollution to water resources. This is a major problem in the rare earth separation industry at present.