Method for preparing anhydrous rare-earth chloride based on spray drying-melting dehydration

Abstract

The invention discloses a method for preparing anhydrous rare-earth chloride based on spray drying-melting dehydration. The method comprises the following steps: S1, preparing a rare-earth chloride heptahydrate into a rare-earth chloride solution with a concentration of not less than 200 g / L; S2, performing spray drying on the rare-earth chloride solution at a temperature of 110-120 DEG C so as toobtain a rare-earth chloride trihydrate; S3, heating and melting the rare-earth chloride trihydrate so as to obtain molten liquor and impurity liquid, wherein in the heating and melting process, thetemperature is 850-1000 DEG C, and the vacuum degree is 50-100mm mercury column; and S4, separating and cooling the molten liquor, thereby obtaining the anhydrous rare-earth chloride. According to themethod disclosed by the invention, the operation of preparing the anhydrous rare-earth chloride from the rare-earth chloride heptahydrate is realized by adopting the spray drying-melting dehydration.The method is simple in process, pollution-free, low in equipment requirement and capable of easily realizing industrialized production; and compared with a general dehydration method in the prior art, the method disclosed by the invention has the advantages that a protective atmosphere is not needed, organic matters or other heavy metals do not need to be introduced, and production of hydrogen chloride or ammonia and other toxic gases is avoided.

Description

technical field [0001] The invention belongs to the technical field of preparation of rare earth chlorides, and specifically relates to a method for preparing anhydrous rare earth chlorides based on a spray drying-melting dehydration method. Background technique [0002] Rare earth elements are located in group IIIB of the periodic table and belong to the lanthanide series. In nature, rare earth elements exist in the form of various compounds, and rare earth trichloride is one of the more important ones. Rare earth is called industrial monosodium glutamate. Clean rare earth chloride is one of the matrix materials for aluminum alloy anti-corrosion protective film, organic reaction catalyst, scintillation crystal material, etc. It is also widely used in the fields of human tumor suppression, agricultural planting, and dye production. At present, solvent extraction, ion exchange, precipitation, etc. are generally used to remove impurities from rare earth oxides. At present, th...

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Problems solved by technology

However, there are certain problems in the above-mentioned methods: the dehydration effect of the decompression dehydration method is not good, the water content in the product is difficult to meet the requirements, and the product purity is not high; there will be redox in the reaction process of ammonium chloride sublimation method to prepare rare earth chloride. The occurrence of the reaction, hydrogen chloride gas and ammonia gas will be generated during the reaction process, the operating conditions are harsh, the risk is high, and it is difficult to obtain anhydrous rare earth chloride with high purity; the anhydrous rare earth chloride prepared by the rare earth oxide chlorination method is generally The water content is 5% to 10%, and the water insoluble matter is 5% to 10%. The product of this method is unstable, and the chlorination temperature is as high as 1050°C to 1100°C. During the chlorination process, chlorine gas will seriously corrode the equipment at high temperature. This method is a high Cost, high energy consumption, high pollution method; THF complex method introduces THF complex in the production process, by-product toxic substances such as HgCl 2 etc., seriously pollute the environment, and the subsequent treatment process is difficult, and the starting material of this method requires high-purity rare earth metals, which is not suitable for large-scale preparation of anhydrous rare earth chloride