阅读说明：本技术 一种高品质无水稀土氯化物、溴化物的制备方法 (Preparation method of high-quality anhydrous rare earth chloride and bromide ) 是由 段西健 温永清 张瑞森 张志宏 赵长玉 张呈祥 郝先库 张瑞祥 杨占峰 于 2018-10-29 设计创作，主要内容包括：本发明提供了一种高品质无水稀土氯化物、溴化物的制备方法,包括以下步骤：(1)将稀土卤化物REX<Sub>3</Sub>·xH<Sub>2</Sub>O进行预脱水,得到粗无水REX<Sub>3</Sub>；其中,X为Br和/或Cl元素,RE为Y、Sc、La、Ce、Pr、Nd、Sm、Pm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu中的任一种或两种以上稀土元素；0≤x≤7；(2)将步骤(1)得到的粗无水REX<Sub>3</Sub>于隔绝水和氧气的条件下抽真空；(3)将步骤(2)中的体系从200-1500℃分若干个阶段进行梯度升温,将目标物REX<Sub>3</Sub>进行蒸馏提纯,获得绝对纯度≥99.99％的高纯无水REX<Sub>3</Sub>。本发明所述的高品质无水稀土氯化物、溴化物的制备方法,将材料中不同物质通过工艺控制分离,进而得到绝对纯度极高的无水稀土卤化物,工艺成本较低,易于工业化生产。(The invention provides a preparation method of high-quality anhydrous rare earth chloride and bromide, which comprises the following steps: (1) pre-dehydrating rare earth halide REX 3. xH2O to obtain crude anhydrous REX 3; wherein, X is Br and/or Cl element, RE is one or more rare earth elements of Y, Sc, La, Ce, Pr, Nd, Sm, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; x is more than or equal to 0 and less than or equal to 7; (2) vacuumizing the crude anhydrous REX3 obtained in the step (1) under the condition of isolating water and oxygen; (3) and (3) performing gradient temperature rise on the system in the step (2) in a plurality of stages from 200-1500 ℃, and performing distillation purification on the target object REX3 to obtain high-purity anhydrous REX3 with absolute purity of more than or equal to 99.99%. The preparation method of the high-quality anhydrous rare earth chloride and bromide, disclosed by the invention, has the advantages that different substances in the material are separated through process control, so that the anhydrous rare earth halide with extremely high absolute purity is obtained, the process cost is lower, and the industrial production is easy to realize.)

1. A preparation method of high-quality anhydrous rare earth chloride and bromide is characterized by comprising the following steps: the method comprises the following steps:

(1) Pre-dehydrating rare earth halide REX 3. xH2O to obtain crude anhydrous REX 3; wherein, X is Br and/or Cl element, RE is one or more rare earth elements of Y, Sc, La, Ce, Pr, Nd, Sm, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; x is more than or equal to 0 and less than or equal to 7;

(2) Vacuumizing a system where the crude anhydrous REX3 obtained in the step (1) is;

(3) And (3) carrying out gradient temperature rise on the system in the step (2) in a plurality of stages from 200-1500 ℃, and carrying out distillation purification on the target REX3 by utilizing the difference of melting points, boiling points and vapor pressures of different substances to obtain high-purity anhydrous REX3 with the absolute purity of more than or equal to 99.99%.

2. The method for preparing high-quality anhydrous rare earth chloride and bromide according to claim 1, wherein: the method also comprises the steps of dissolving rare earth carbonate or oxide or hydroxide by using hydrochloric acid or hydrobromic acid to obtain a clear rare earth halide REX3 solution, and concentrating and crystallizing to obtain REX 3. xH2O, wherein the step is positioned before the step (1).

3. The method for preparing high-quality anhydrous rare earth chloride and bromide according to claim 2, wherein: in the step (1), the rare earth halide REX 3. xH2O is pre-dehydrated to obtain LaOBr and crude anhydrous REX 3.

4. The method for preparing high-quality anhydrous rare earth chloride and bromide according to claim 1, wherein: in step (1), the pre-dehydration of REX3 · xH2O may be performed in air, an inert atmosphere, a vacuum state, or a hydrogen halide atmosphere, wherein the hydrogen halide is HBr or HCl corresponding to the X element in REX 3.

5. the method for preparing high-quality anhydrous rare earth chloride and bromide according to claim 1, wherein: in the step (3), the air pressure in the distillation system is less than or equal to 3000 Pa; preferably, in the step (3), the air pressure in the distillation system is less than or equal to 1000 Pa; more preferably, in the step (3), the air pressure in the distillation system is less than or equal to 100 Pa; more preferably, in step (3), the pressure in the distillation system is less than or equal to 10 Pa.

6. the method for preparing high-quality anhydrous rare earth chloride and bromide according to claim 1 or 5, wherein: in the step (3), gradient temperature rise is carried out in the following four stages:

The first stage, raising the temperature to 200-300 ℃, keeping the temperature for 2-12H, and removing residual H2O in crude anhydrous REX 3;

The second stage, on the basis of the first stage, continuously raising the temperature to 400-600 ℃, keeping the temperature for 2-10h, and removing impurities with low boiling point or large vapor pressure in the crude anhydrous REX3 through gasification;

in the third stage, on the basis of the second stage, continuously heating to 600-850 ℃, keeping for 4-14h, removing residual carbon in the crude anhydrous REX3, and removing impurities FeX2, CaX3 and NaX 3;

And a fourth stage, continuing to heat to 650-1500 ℃ on the basis of the third stage, keeping the temperature for 12-50h, distilling and collecting a target object REX3 to obtain high-purity anhydrous REX 3.

7. The method for preparing high-quality anhydrous rare earth chloride and bromide according to claim 6, wherein: in the step (3), the temperature rise rate in the whole gradient temperature rise process is less than or equal to 20 ℃/min; preferably; in the step (3), the temperature rise rate in the whole gradient temperature rise process is less than or equal to 10 ℃/min; more preferably, in the step (3), the temperature rise rate in the whole gradient temperature rise process is less than or equal to 5 ℃/min.

8. the method for preparing high-quality anhydrous rare earth chloride and bromide according to claim 1, wherein: in the step (1), in the crude anhydrous REX3 obtained by dehydrating REX 3. xH2O, the content of H2O is less than or equal to 1 wt%; preferably, in the step (1), the content of H2O in the crude anhydrous REX3 obtained by dehydrating REX 3. xH2O is less than or equal to 0.1 wt%; the method also comprises the step of collecting and packaging the high-purity anhydrous REX3 obtained in the step (3) under the condition of isolating water and oxygen, wherein the condition of isolating water and oxygen refers to a system environment with the content of water and oxygen being less than or equal to 3 ppm.

9. The method for preparing high-quality anhydrous rare earth chloride and bromide according to claim 1, wherein: in the step (3), the water content in the obtained high-purity anhydrous REX3 is less than or equal to 50ppm, and the oxygen content is less than or equal to 100 ppm.

10. The method for preparing high-quality anhydrous rare earth chloride and bromide according to claim 1, wherein: in step (3), REX3 is one or a mixture of two or more of ScCl3, YCl3, LaCl3, CeCl3, PrCl3, NdCl3, PmCl3, SmCl3, EuCl3, GdCl3, TbCl3, DyCl3, HoCl3, ErCl3, TmCl3, YbCl3, LuCl3, ScBr3, YBr3, LaBr3, CeBr3, PrBr3, NdBr3, PmBr3, SmBr3, EuBr3, GdBr3, TbBr3, DyBr3, HoBr3, ErBr3, TmBr3, YbBr3, and LuBr 3.

Technical Field

The invention belongs to the field of preparation of inorganic materials, and particularly relates to a preparation method of high-quality anhydrous rare earth chloride and bromide.

background

scintillation crystals are crystals that emit visible light or ultraviolet light under the action of rays (X rays, alpha rays, beta rays) or high-energy particles (neutrons, etc.), and have wide applications in nuclear medicine imaging, high-energy physics, geological exploration, space exploration, petroleum exploration, nondestructive inspection, safety inspection, etc.

In recent 20 years, the research on halide scintillators has been rapidly developed, and a large number of novel scintillation crystals with high light output and good energy resolution or simultaneously with the capability of distinguishing gamma rays and neutrons emerge successively. Among them, rare earth halide scintillator materials represented by LaBr3: Ce3+ and LaCl3: Ce3+ have attracted much attention due to their characteristics of high luminous efficiency, fast attenuation, high energy resolution, high spatial resolution, small nonlinear response, and the like. These scintillator materials typically require crystal preparation starting from highly pure anhydrous rare earth chlorides or bromides. However, due to the difficulty in dehydration, oxyhalides are easily generated in the dehydration process, and the finished product is very easy to deliquesce, which brings great difficulties to the preparation, packaging, storage, crystal growth and the like of raw materials. At present, the high-purity anhydrous rare earth halide meeting the growth requirement of the scintillator has tens of thousands of selling prices per kilogram in the market, the CeBr3 has more than 6 ten thousand yuan per kilogram, and the development of the rare earth halide scintillator industry is seriously hindered by the high price. Therefore, the anhydrous rare earth halide preparation method which is low in cost and easy to prepare in a large scale is provided, and great promotion effect on development and application of the rare earth halide scintillator material is certainly achieved.

disclosure of Invention

In view of the above, the present invention aims to provide a method for preparing high-quality anhydrous rare earth chlorides and bromides, so as to overcome the defects of the prior art, separate different substances in the material through process control, further obtain anhydrous rare earth halides with extremely high absolute purity, and have the advantages of low process cost and easy industrial production.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

A preparation method of high-quality anhydrous rare earth chloride and bromide comprises the following steps:

(1) Pre-dehydrating rare earth halide REX 3. xH2O to obtain crude anhydrous REX 3; wherein, X is Br and/or Cl element, RE is one or more rare earth elements of Y, Sc, La, Ce, Pr, Nd, Sm, Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; x is more than or equal to 0 and less than or equal to 7;

(2) Vacuumizing a system where the crude anhydrous REX3 obtained in the step (1) is;

(3) and (3) carrying out gradient temperature rise on the system in the step (2) in a plurality of stages from 200-1500 ℃, and carrying out distillation purification on the target REX3 by utilizing the difference of melting points, boiling points and vapor pressures of different substances to obtain high-purity anhydrous REX3 with the absolute purity of more than or equal to 99.99%.

Preferably, the preparation method of the high-quality anhydrous rare earth chloride and bromide further comprises the steps of dissolving rare earth carbonate or oxide or hydroxide by using hydrochloric acid or hydrobromic acid to obtain a clear rare earth halide REX3 solution, and concentrating and crystallizing to obtain REX 3. xH2O, wherein the step is positioned before the step (1). The process of dissolving the rare earth carbonate or oxide or hydroxide by using hydrochloric acid or hydrobromic acid is specifically as follows: weighing a proper amount of rare earth carbonate or oxide or hydroxide, gradually adding the rare earth carbonate or oxide or hydroxide, and completely dissolving the rare earth carbonate or oxide or hydroxide into a proper amount of concentrated hydrochloric acid or concentrated hydrobromic acid (added according to a stoichiometric ratio) until the pH of the solution is 5-7, namely the mass ratio of the rare earth elements to the acid is 1: 3; wherein, concentrated hydrochloric acid or concentrated hydrobromic acid is generally commercially available super-grade pure or analytically pure concentrated hydrochloric acid, and the concentration is generally 36-38%.

Preferably, in step (1), the rare earth halide REX 3. xH2O is pre-dehydrated to obtain LaOBr and crude anhydrous REX 3.

Preferably, in step (1), the pre-dehydration of REX3 · xH2O can be performed under air, inert atmosphere, vacuum state or hydrogen halide atmosphere, wherein the hydrogen halide is HBr or HCl corresponding to the X element in REX3, i.e. during the preparation of rare earth chlorides and bromides, the hydrogen halide gas is hydrogen chloride and hydrogen bromide.

Preferably, in the step (3), the air pressure in the distillation system is less than or equal to 3000 Pa; preferably, in the step (3), the air pressure in the distillation system is less than or equal to 1000 Pa; more preferably, in the step (3), the air pressure in the distillation system is less than or equal to 100 Pa; more preferably, in step (3), the pressure in the distillation system is less than or equal to 10 Pa.

Preferably, in the step (3), the temperature is increased in a gradient manner in the following four stages:

The first stage, raising the temperature to 200-300 ℃, keeping the temperature for 2-12H, and removing residual H2O in crude anhydrous REX 3;

The second stage, on the basis of the first stage, continuously raising the temperature to 400-600 ℃, keeping the temperature for 2-10h, and removing impurities with low boiling point or large vapor pressure in the crude anhydrous REX3 by gasification, such as NH3X, SiX4, FeX3 and the like;

In the third stage, on the basis of the second stage, continuously heating to 600-850 ℃, keeping for 4-14h, removing residual carbon in the crude anhydrous REX3, and removing impurities such as FeX2, CaX3, NaX3 and the like;

And a fourth stage, continuing to heat to 650-1500 ℃ on the basis of the third stage, keeping the temperature for 12-50h, distilling and collecting a target object REX3 to obtain high-purity anhydrous REX 3.

the temperature overlapping region of the third stage and the fourth stage is caused by different melting points of different substances, wherein the melting point of one substance is lower, so that the distillation temperature of the substance is possibly lower than the impurity removal temperature of the other substance.

Preferably, in the step (3), the temperature rise rate in the whole gradient temperature rise process is less than or equal to 20 ℃/min; preferably; in the step (3), the temperature rise rate in the whole gradient temperature rise process is less than or equal to 10 ℃/min; more preferably, in the step (3), the temperature rise rate in the whole gradient temperature rise process is less than or equal to 5 ℃/min.

Preferably, in the step (1), the content of H2O in the crude anhydrous REX3 obtained by dehydrating REX 3. xH2O is less than or equal to 1 wt%; preferably, in the step (1), the content of H2O in the crude anhydrous REX3 obtained by dehydrating REX 3. xH2O is less than or equal to 0.1 wt%; the method also comprises the step of collecting and packaging the high-purity anhydrous REX3 obtained in the step (3) under the condition of water and oxygen isolation, wherein the water and oxygen isolation condition refers to a system environment with the water and oxygen content less than or equal to 3ppm, the requirements can be met in a commercially available circulating glove box and a drying chamber, and in addition, the requirements can be met by high-purity inert gas.

Preferably, in the step (3), the obtained high-purity anhydrous REX3 has the water content of less than or equal to 50ppm and the oxygen content of less than or equal to 100 ppm.

Preferably, in step (3), REX3 is one or a mixture of two or more of ScCl3, YCl3, LaCl3, CeCl3, PrCl3, NdCl3, PmCl3, SmCl3, EuCl3, GdCl3, TbCl3, DyCl3, HoCl3, ErCl3, TmCl3, YbCl3, LuCl3, ScBr3, YBr3, LaBr3, CeBr3, PrBr3, NdBr3, pm 3, SmBr3, EuBr3, GdBr3, TbBr3, DyBr3, HoBr3, ErBr3, TmBr3, YbBr3, and LuBr 3.

the reagents and raw materials used in the invention are commercially available, and the industrial purity and higher purity can meet the requirements.

Compared with the prior art, the preparation method of the high-quality anhydrous rare earth chloride and bromide has the following advantages:

Compared with the traditional process, the process can separate different substances in the material by process control, so as to obtain the anhydrous rare earth halide with extremely high absolute purity, and meanwhile, because water and oxygen are isolated in the preparation process, the pollution can be avoided; in addition, the process cost is low, and the industrial production is easy to realize.

After crude anhydrous REX3 is obtained, four-stage gradient temperature rise is carried out in a vacuum, oxygen-free and water-free environment, wherein the first stage (below 300 ℃) is used for strictly removing water, the second stage (400-.

Drawings

FIG. 1 is a process flow chart of the present invention using crude lanthanum bromide as an example.

Detailed Description

Unless defined otherwise, technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods are conventional methods unless otherwise specified.

The present invention will be described in detail with reference to the following examples and accompanying drawings.

The products of the following examples, prepared by the process of the present invention, were treated under exclusion of water and oxygen (water and oxygen content: 3ppm or less), for example, collected and packaged in a commercially available circulating glove box, and will not be described again. The following is an illustration of the product preparation (steps prior to collection and packaging), as seen in examples 1-5.