Method for preparing anhydrous praseodymium chloride on basis of spray drying-melting dehydration

Abstract

The invention discloses a method for preparing anhydrous praseodymium chloride on the basis of spray drying-melting dehydration. The method comprises the following steps: S1, a praseodymium chloride solution with concentration not lower than 200 g / L is prepared from praseodymium chloride heptahydrate; S2, the praseodymium chloride solution is subjected to spray drying at 110-120 DEG C, and praseodymium chloride trihydrate is obtained; S3, praseodymium chloride trihydrate is subjected to heating melting, and a clear melted liquid and an impurity liquid are obtained, wherein a mercury column atthe temperature of 760-1000 DEG C and the vacuum degree of 50-100 mm is adopted in the heating melting process; S4, separation and cooling are performed on the clear melted liquid, and anhydrous praseodymium chloride is obtained. According to the method, anhydrous praseodymium chloride is prepared from praseodymium chloride heptahydrate with the spray drying-melting dehydration method, the processis simple, pollution is avoided, equipment requirements are low, and industrial production is easy to realize; compared with the general dehydration method in the prior art, protective atmosphere isnot needed, introduction of organic matter or other heavy metals is not needed, and poisonous gases such as hydrogen chloride or ammonia gas and the like are not produced.

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 praseodymium chloride based on a spray drying-melting dehydration method. Background technique [0002] Praseodymium, element symbol Pr, atomic number 59, atomic weight 140.91, is located in group IIIB of the periodic table of elements, belongs to the lanthanide element, and is also a rare earth element. Praseodymium trichloride is generally used to prepare metal praseodymium and praseodymium compounds, glass, and ceramic coloring. At present, solvent extraction, ion exchange, precipitation, etc. are generally used to remove impurities from rare earth oxides. At present, the preparation methods of anhydrous praseodymium chloride mainly include: (1) dehydration under reduced pressure of crystal water and rare earth chlorides, (2) ) ammonium chloride sublimation method, (3) rare earth oxide chlorination method...

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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