Technology for extraction and separation of thorium and rare earth

Abstract

The invention provides a technology for extraction and separation of thorium and rare earth, wherein the technology comprises the steps: firstly, dissolving prior dissolved slag produced in a monazite treatment alkaline-process technology by using hydrochloric acid to obtain a material liquid containing thorium, rare earth and uranium; taking P350 as an extractant, extracting and separating thorium and rare earth in the material liquid containing thorium and rare earth in a high-acidity hydrochloric acid system, to obtain a thorium-loaded organic phase and a raffinate; washing the thorium-loaded organic phase with high-acidity HCl, then carrying out back extraction by using a solution containing HNO3 and NaNO3 to obtain Th(NO3)4 back-extracted solution; and allowing the raffinate containing rare earth and high-concentration hydrochloric acid and obtained from extraction and separation to return to a prior dissolving process. The separation coefficient of thorium and rare earth can be effectively improved in the high-acidity extraction system, the separation efficiency is improved, the separation effect of rare earth and thorium is improved, high-purity thorium nitrate is obtained, rare earth and other valuable elements in the raffinate are comprehensively recycled, the hydrochloric acid in the raffinate is comprehensively utilized, the utilization rate of resources is improved, the postprocessing process is reduced, environment pollution is reduced, and the comprehensive utilization of the resources is achieved.

Description

technical field [0001] The invention relates to a process for extracting and separating thorium and rare earths. Specifically, P350 is used as an extractant to extract and separate thorium and rare earths from a solution containing thorium and rare earths in a high-concentration hydrochloric acid system, which belongs to the field of hydrometallurgical separation. Background technique [0002] Monazite is one of the important rare earth ores. The caustic soda decomposition method is widely used in industry to process monazite concentrate to obtain alkali decomposition slurry, and the rare earth hydroxide solid and sodium phosphate solution are obtained through solid-liquid separation; the rare earth hydrogen obtained by hydrochloric acid is Oxide solids are subjected to refractory treatment to obtain RECl 3 Solution and excellent slag; ("Rare Earth", first edition volume, Metallurgical Industry Press 1978, P221-237), excellent slag after extracting rare earth, that is, urani...

AI Technical Summary

Problems solved by technology

[0004] The main disadvantage of the above process is that when the P350-hydrochloric acid system separates the chloride solution containing U, Th, RE, and Fe, the raffinate containing thorium and rare earth is first obtained, and the acidity is generally about 2.5mol / L. The liquid is extracted and separated by P350, and the rare earth-containing raffinate and the organic material loaded with pure thorium are obtained

The main problem of the above process is that, due to the relatively low acidity of the operation, the tetravalent titanium in the system is easily hydrolyzed to generate titanium hydroxy complexes and titanium oxide, etc., and it is easy to form three-phase substances during the extraction process, resulting in poor extraction and phase separation. , leading to continuous operation can not be carried out, the feed liquid must be hydrolyzed to remove Ti, adjust the pH value and multiple filtration, clarification and washing treatment, which brings difficulties in operation, and consumes hydrochloric acid at the same time, which brings difficulties in operation; and in the case of low acidity, In the P350 system, the RE and Th separation coefficients are small, and the process needs to be adjusted by increasing the number of extraction and washing stages and the amount of acid used for washing, which greatly increases the operating cost.