Technique for extraction separation of quadravalence cerium, thorium, fluorine and cerium less tervalence rare earth from sulphuric acid rare earth solution

Abstract

The invention relates to a technological method for extracting and separating quadrivalent cerium, thorium, fluorine and less-cerium trivalent rare-earth from rare earth sulfate solution. The rare earth sulfate solution, which is obtained through processing the rare-earth ores and contains high-valence cerium, the fluorine, the thorium and ferrum, is used as raw material; synergistic extraction agent basing on P507 and P204 is adopted for extracting and separating; the cerium (1V), the thorium, the fluorine, and the ferrum are extracted into an organic phase, then selective washing and back extraction are performed step by step to obtain three products that are the cerium, the fluorine, and the thorium, the trivalent rare-earth is left in a water phase, and then unsaponifiable P507 or thesynergistic extraction agent basing on P507 is adopted to perform multistage fractional extraction to separate single rare earth elements. The technological method has the characteristics that the synergistic extraction agent basing on P507 and P204 is adopted, the thorium is easy to perform the back extraction, and extraction capacity is large, and the emulsification is not generated during the extraction process; the cerium (1V), the thorium, the fluorine, the ferrum and the trivalent rare-earth are extracted and separated in the same extraction system; both extraction and the separation adopt unsaponifiable extraction agent, and ammonia-nitrogen wastewater is not generated; in addition, the thorium and the fluorine are recovered as products, and the pollutions caused by thorium-containing waste residue, fluoride-containing wastewater and the ammonia-nitrogen wastewater are eliminated from headstream. Therefore, the technological method has the advantages of simple procedures, greenenvironmental protection, and low manufacturing cost.

Description

technical field [0001] The invention relates to a process for extracting and separating cerium (IV), thorium, fluorine and cerium-less trivalent rare earth from a rare earth sulfate solution containing thorium, fluorine and high-valent cerium. Rare earth sulfate solution with high valence cerium is used as raw material, and the non-saponification co-extractant based on P507 or P204 is used for extraction and separation. The invention belongs to the field of rare earth hydrometallurgy. Background technique [0002] my country is a big country with rare earth resources, and the rare earth industry has occupied a leading position in the world. With the continuous expansion of the scale of the rare earth industry, the low utilization rate of resources and the pollution of three wastes generated in the process of rare earth smelting and separation are becoming more and more serious. For example, Sichuan bastnaesite is the second largest rare earth resource in my country. At pre...

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Problems solved by technology

For example, Sichuan bastnaesite is the second largest rare earth resource in my country. At present, the industry mainly adopts oxidative roasting-hydrochloric acid leaching of trivalent rare earths, cerium, fluorine and part of thorium are enriched in the slag, and then the fluorine is removed by alkali decomposition, and then hydrochloric acid is used to extract the trivalent rare earths. Excellent solution reclaims cerium, and this process has following problems: 1) the purity of cerium product is low, is 97%-98% (CeO 2 / TREO); 2) Thorium enters the waste residue, and thorium is discharged into the environment along with the waste residue, causing radioactive pollution and waste of resources; 3) In the process, a large amount of water is used to wash and remove fluorine, and fluorine is discharged into the environment in the waste water, causing serious damage to water resources pollution, and waste of fluorine resources at the same time; 4) cross-use of acid and alkali in the process, high consumption of chemical raw materials such as acid and alkali

However, this method does not consider the separation and recovery of thorium and trivalent rare earths. Using extractants such as P204, thorium back-extraction is very difficult, and it will also poison the extractant, making it difficult for the extraction process to run smoothly for a long time

[0006] Chinese patent 94111277.2 discloses leaching extraction method to separate cerium oxide and cerium-less mixed rare earths. This invention is to extract rare earth minerals represented by bastnaesium in mineral acid, and thorium and cerium (IV) are extracted into P507 or P204 or TBP In the organic phase, hydrogen peroxide is used to back-extract cerium, and RE(III) enters the raffinate aqueous phase and is extracted during the leaching process. The behavior of impurity ions is relatively complicated. Solid-liquid extraction results in a large loss of extractant and is difficult to industrialize.

[0007] The above-mentioned process has the following problems: while the rare earth products are obtained through extraction and separation, other non-rare earth elements such as fluorine and thorium are not effectively recovered, either only the recovery of fluorine is considered, or the extraction of thorium is only considered, and a thorough Process solutions to solve environmental pollution and resource waste

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