阅读说明：本技术 一种稀土氟化物及其制备方法和用途 (Rare earth fluoride and preparation method and application thereof ) 是由 肖吉昌 宗国强 安华英 余东海 于 2020-12-25 设计创作，主要内容包括：本发明涉及一种稀土氟化物及其制备方法和用途,所述方法包括：将闪烁晶体废料的粉末在混合气氛下进行热处理,之后在保护气氛下冷却,得到所述稀土氟化物。本发明将闪烁晶体废料粉碎研磨成细粉,洗涤后真空高温干燥除水除杂,然后将其进行高温处理,硅酸(钇)镥中的硅和氧元素转化为气态的SiF-4和H-2O排出,经碱液吸收。氟化反应炉内的高纯稀土氟化物经自然冷却后取出,可用于制备高纯金属、荧光材料、特种添加剂和其它高端材料,因其杂质和氧含量极低,可用于还原法制备高纯稀土金属。(The invention relates to a rare earth fluoride and a preparation method and application thereof, wherein the method comprises the following steps: and carrying out heat treatment on the powder of the scintillation crystal waste in a mixed atmosphere, and then cooling in a protective atmosphere to obtain the rare earth fluoride. The invention crushes and grinds the scintillation crystal waste into fine powder, dries at high temperature in vacuum after washing to remove water and impurities, then carries out high-temperature treatment to convert silicon and oxygen elements in lutetium oxyorthosilicate (yttrium) into gaseous SiF 4 And H 2 Discharging O, and absorbing with alkali solution. The high-purity rare earth fluoride in the fluorination reaction furnace is naturally cooled and taken out, can be used for preparing high-purity metals, fluorescent materials, special additives and other high-end materials, and can be used for preparing high-purity metals, fluorescent materials, special additives and other high-end materials due to extremely low impurity and oxygen contentsThe original method is used for preparing high-purity rare earth metal.)

1. A method for preparing rare earth fluoride from scintillation crystal waste, characterized in that the method comprises: and carrying out heat treatment on the powder of the scintillation crystal waste in a mixed atmosphere, and then cooling in a protective atmosphere to obtain the rare earth fluoride.

2. The method of claim 1, wherein the scintillation crystal waste comprises lutetium silicate waste and/or yttrium lutetium silicate waste.

3. The method according to claim 1 or 2, wherein the powder is obtained by subjecting the scintillation crystal to pulverization, sieving, washing, and drying in this order;

preferably, the mesh number of the screen in the screening is 60-200 meshes;

preferably, the cleaning is performed by water;

preferably, the drying mode is vacuum drying;

preferably, the temperature of the drying is 600-;

preferably, the drying time is 5-20 h.

4. The method of any one of claims 1-3, wherein the mixed atmosphere comprises hydrogen fluoride gas and an inert gas;

preferably, the volume ratio of the hydrogen fluoride gas to the inert gas in the mixed atmosphere is 1 (1-10).

5. The method according to any one of claims 1 to 4, wherein the temperature of the heat treatment is 600 ℃ and 1000 ℃.

6. The method according to any one of claims 1 to 5, wherein the heat treatment time is 10 to 40 h.

7. The method of any one of claims 1-6, wherein the protective atmosphere comprises nitrogen and/or an inert gas.

8. The method of any one of claims 1-7, wherein the method comprises: carrying out heat treatment on the powder of the scintillation crystal waste in a mixed atmosphere, and then cooling in a protective atmosphere to obtain the rare earth fluoride;

the scintillation crystal waste comprises lutetium silicate waste and/or yttrium lutetium silicate waste; the powder is obtained by sequentially crushing, screening, cleaning and drying the scintillation crystal;

the mixed atmosphere comprises hydrogen fluoride gas and inert gas, and the volume ratio of the hydrogen fluoride gas to the inert gas in the mixed atmosphere is 1 (1-10); the temperature of the heat treatment is 600-1000 ℃, and the time of the heat treatment is 10-40 h.

9. Rare earth fluoride obtainable by the process according to any of claims 1 to 8, characterized in that it has an oxygen content of < 100 ppm;

preferably, the purity of the rare earth fluoride is more than or equal to 99.99%.

10. Use of rare earth fluorides according to claim 9 for preparing one of high purity metals or laser crystals.

Technical Field

The invention relates to the field of solid waste recycling, in particular to a rare earth fluoride and a preparation method and application thereof.

Background

Rare earth is called as industrial gold, has excellent physical properties such as photoelectromagnetism and the like, can form novel materials with various properties and varieties with other materials, is widely applied to more than 40 industries in 13 fields such as metallurgical machinery, petrochemical industry, light industry and agriculture, electronic information, energy environmental protection, national defense and military industry, high and new materials and the like, is a traditional industry for transformation of countries in the world at present, and is indispensable strategic material for developing high and new technologies and national defense advanced technologies.

In recent years, lutetium-based compounds have attracted great interest due to their advantages of high density and rapid decay, and become a research focus in this field, especially lutetium silicate (Lu)₂SiO₅LSO), lutetium yttrium silicate (Lu)_2(1-x)Y_2xSiO₅LYSO) as representative lutetium-based scintillation crystal, which integrates a plurality of advantages of high density, short afterglow, high light yield and the like into a whole and has become a substituted Bi₄Ge₃O₁₂The emergence of (BGO) crystals for the most powerful competitors of PET (positron emission tomography) equipment, especially the commercial clinical LSO crystal-based PET devices, has accelerated the consumption of LSO crystals. But at least 20% of cutting scraps are generated in the production process of the LSO crystal, lutetium is one of the most valuable and deficient rare earth elements, the lutetium oxide content in the waste material is up to more than 70%, and the recovery value is very high.

At present, researches on comprehensive recovery of rare earth elements from lutetium (yttrium) silicate scintillation crystal waste are few, and the adopted method mainly comprises the steps of extracting the rare earth elements into acid leaching solution by using a high-concentration strong acid solution, then separating and recovering the rare earth elements by using an organic extractant through regulating the pH value of the acid leaching solution, and preparing rare earth oxides through precipitation and ignition. For example, CN110042245A discloses a method for recovering and purifying lutetium from lutetium yttrium silicate scintillation crystal waste, which comprises using lutetium yttrium silicate waste obtained by laser cutting lutetium yttrium silicate scintillation crystal as raw material, mixing the raw material with alkali fusing agent according to a certain proportion, carrying out thermal decomposition at a certain temperature, cooling, leaching with hydrochloric acid, and converting lutetium yttrium silicate into lutetium yttrium chloride solution. And the lutetium yttrium chloride solution after sodium and silicon removal is synergistically extracted and separated by P507 and C272 to obtain purified LuCl₃The liquid is precipitated by oxalic acid, burned and the like to synthesize the high-purity lutetium oxide, and the purity of lutetium reaches 99.999 percent.

CN103436719A discloses lutetium oxide recovered from scintillation crystal waste doped with lutetium cerium aluminate and a recovery method. The method comprises the following steps:

s1, adding sodium hydroxide and/or potassium hydroxide into the scintillation crystal waste, and roasting to obtain a roasted product;

s2, soaking the roasted product in water, filtering, adding nitric acid and an oxidant into the obtained filter residue, and stirring to obtain a mixed solution;

s3, adding the mixed solution into an organic extractant, and extracting to obtain an extract containing cerium and a raffinate containing lutetium;

s4, adding oxalic acid into the lutetium-containing raffinate, stirring, filtering, and burning the obtained precipitate to obtain lutetium oxide. The process obtains the lutetium oxide with the purity of 99 percent and the recovery rate of 99.5 percent, has short process flow, less equipment investment, simple and easy operation, saves resources, reduces pollution, has huge practical value and provides a new way for recovering lutetium from the scintillation crystal waste material doped with cerium lutetium aluminate.

However, the above treatment process is complicated in operation, high in cost, low in added value and large in water consumption.

Disclosure of Invention

In view of the problems in the prior art, the invention aims to provide a rare earth fluoride and a preparation method and application thereof, so that the purposes of efficient comprehensive utilization of rare earth resources and environment-coordinated development are realized, the high-purity rare earth fluoride is prepared by directly fluorinating lutetium yttrium silicate waste, the added value is high, the operation is simple and convenient, the environment is friendly, and the double benefits of economy and environment are achieved.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a method for preparing rare earth fluoride from scintillation crystal waste, which comprises the following steps: and carrying out heat treatment on the powder of the scintillation crystal waste in a mixed atmosphere, and then cooling in a protective atmosphere to obtain the rare earth fluoride.

The method comprises the steps of crushing and grinding the scintillation crystal waste into fine powder, washing, drying at high temperature in vacuum to remove water and impurities, and then carrying out the treatment in a specific atmosphereHigh temperature treatment, silicon and oxygen in lutetium oxyorthosilicate are converted into SiF in gas state₄And H₂Discharging O, and absorbing with alkali solution. The high-purity rare earth fluoride in the reaction device is naturally cooled and then taken out, so that the high-purity rare earth fluoride can be used for preparing high-purity metals, fluorescent materials, special additives and other high-end materials, and can be used for preparing the high-purity rare earth metals by a reduction method due to extremely low impurity and oxygen contents. The invention not only recovers the rare earth elements, but also forms new high-added-value high-purity rare earth fluoride, thereby not only meeting the requirements of saving rare earth resources and reasonably utilizing the rare earth resources, but also reducing the environmental pollution and meeting the requirements of environmental protection. The method separates the rare earth from silicon and oxygen, converts the rare earth into rare earth fluoride with high additional value, thereby achieving the purpose of recovering the rare earth, and has the advantages of simple and easy operation, high additional value, environmental protection, resource saving and environmental protection.

As a preferred technical scheme of the invention, the scintillation crystal waste material comprises lutetium silicate waste material and/or yttrium lutetium silicate waste material.

As a preferable technical scheme of the invention, the powder is obtained by sequentially crushing, screening, cleaning and drying the scintillation crystal.

Preferably, the mesh number of the screen in the screening is 60 to 200 mesh, for example, 60 mesh, 80 mesh, 100 mesh, 120 mesh, 140 mesh, 180 mesh or 200 mesh, etc., but is not limited to the enumerated values, and other values not enumerated within the range are also applicable.

Preferably, the cleaning is performed with water.

Preferably, the drying mode is vacuum drying.

In the invention, the vacuum drying equipment comprises a smelting furnace, a resistance furnace, a box-type atmosphere furnace and the like; removing volatile impurities and moisture at high temperature.

Preferably, the drying temperature is 600-1000 deg.C, such as 600 deg.C, 700 deg.C, 800 deg.C, 900 deg.C or 1000 deg.C, but not limited to the recited values, and other values not recited in this range are also applicable.

Preferably, the drying time is 5 to 20 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, or 20 hours, etc., but not limited to the recited values, and other values not recited in the range are also applicable.

As a preferable technical scheme of the invention, the mixed atmosphere comprises hydrogen fluoride gas and inert gas.

In the present invention, the inert gas may be 1 or a combination of at least 2 of helium, neon, or argon, and the like.

The volume ratio of the hydrogen fluoride gas to the inert gas in the mixed atmosphere is preferably 1 (1-10), and examples thereof include, but are not limited to, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, and 1:10, and other values not listed in the range are also applicable.

In a preferred embodiment of the present invention, the heat treatment temperature is 600-1000 deg.C, and may be, for example, 600 deg.C, 650 deg.C, 700 deg.C, 750 deg.C, 800 deg.C, 850 deg.C, 900 deg.C, 950 deg.C, or 1000 deg.C, but is not limited to the values listed above, and other values not listed above in this range are also applicable.

In a preferred embodiment of the present invention, the heat treatment time is 10 to 40 hours, and may be, for example, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours, or 40 hours, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.

In the present invention, the reaction furnace in the heat treatment is a static or dynamic rotary furnace, and preferably a rotary furnace. The crucible is made of materials such as graphite or platinum which are resistant to hydrogen fluoride corrosion.

As a preferred embodiment of the present invention, the protective atmosphere comprises nitrogen and/or an inert gas.

As a preferred technical solution of the present invention, the method comprises: carrying out heat treatment on the powder of the scintillation crystal waste in a mixed atmosphere, and then cooling in a protective atmosphere to obtain the rare earth fluoride;

the scintillation crystal waste comprises lutetium silicate waste and/or yttrium lutetium silicate waste; the powder is obtained by sequentially crushing, screening, cleaning and drying the scintillation crystal;

the mixed atmosphere comprises hydrogen fluoride gas and inert gas, and the volume ratio of the hydrogen fluoride gas to the inert gas in the mixed atmosphere is 1 (1-10); the temperature of the heat treatment is 600-1000 ℃, and the time of the heat treatment is 10-40 h.

In a second aspect, the present invention provides a rare earth fluoride obtained by the process of the first aspect, said rare earth fluoride having an oxygen content of < 100ppm, such as 95ppm, 90ppm, 85ppm, 80ppm, 75ppm, 70ppm, 65ppm, 60ppm, 55ppm or 50ppm, but not limited to the recited values, and other values not recited in this range are equally applicable.

Preferably, the purity of the rare earth fluoride is 99.99% or more, and may be, for example, 99.99%, 99.995%, 99.999%, 99.9995%, 99.9999%, 99.99995%, 99.99999%, or the like, but is not limited to the enumerated values, and other values not enumerated within this range are also applicable.

In a third aspect, the present invention provides the use of a rare earth fluoride as described in the second method for the preparation of one of a high purity metal or a laser crystal.

Compared with the prior art, the invention at least has the following beneficial effects:

(1) the method provided by the invention is utilized to separate rare earth from silicon and oxygen, and the rare earth is converted into rare earth fluoride with high addition value, so that the purpose of recovering the rare earth is achieved.

(2) The method is simple and easy to operate, has high added value and environmental protection, has double benefits of resource saving and environmental protection, and can be used for preparing high-purity metal or laser crystals, and the purity of the obtained rare earth fluoride is more than or equal to 99.99%.

Detailed Description

To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:

example 1

The embodiment provides a method for preparing rare earth fluoride from scintillation crystal waste, which specifically comprises the following steps:

(1) 500g of lutetium silicate scintillation crystal waste is crushed and sieved by a 100-mesh sieve, and then is washed for 3 times by 50L of deionized water and filtered;

(2) then putting the mixture into a vacuum drying smelting furnace, and keeping the temperature of 600 ℃ for vacuum drying for 10 hours;

(3) putting the dried powder into a high-purity graphite crucible of a fluorination reaction furnace, introducing mixed gas of dry HF gas and Ar gas in a volume ratio of 1:3 for reaction at 700 ℃ for 48 hours to generate gaseous SiF₄And H₂Absorbing tail gas such as O and the like by a sodium hydroxide solution;

(4) naturally cooling the prepared lutetium fluoride to room temperature under the protection of nitrogen;

the prepared rare earth lutetium fluoride has the purity of 99.99 percent, the yield of 98.5 percent and the oxygen content of 85ppm, and can be used for preparing high-purity metal and laser crystals.

Example 2

The embodiment provides a method for preparing rare earth fluoride from scintillation crystal waste, which specifically comprises the following steps:

(1) 500g of yttrium lutetium silicate scintillation crystal waste is crushed and sieved by a 100-mesh sieve, and then is washed for 3 times by 50L of deionized water and filtered;

(2) then putting the mixture into a vacuum drying smelting furnace, and keeping the temperature at 800 ℃ for vacuum drying for 20 hours;

(3) putting the dried powder into a high-purity graphite crucible of a fluorination reaction furnace, introducing mixed gas of dry HF gas and nitrogen gas in a volume ratio of 1:3 for reaction at 900 ℃ for 10 hours, and generating gaseous SiF in the reaction process₄And H₂Absorbing tail gas such as O and the like by potassium hydroxide solution;

(4) naturally cooling the prepared yttrium lutetium fluoride to room temperature under the protection of argon;

the obtained rare earth lutetium yttrium fluoride has the purity of 99.99 percent and the oxygen content of 92ppm by analysis, and can be used for preparing rare earth alloy.

Example 3

The embodiment provides a method for preparing rare earth fluoride from scintillation crystal waste, which specifically comprises the following steps:

(1) 500g of yttrium lutetium silicate scintillation crystal waste is crushed and sieved by a 100-mesh sieve, and then is washed for 2 times by 50L of deionized water and filtered;

(2) then putting the mixture into a vacuum drying smelting furnace, and keeping the temperature at 800 ℃ for vacuum drying for 20 hours;

(3) putting the dried powder into a high-purity graphite crucible of a fluorination reaction furnace, introducing mixed gas of dry HF gas and nitrogen gas in a volume ratio of 1:7 for reaction at 700 ℃ for 17 hours, and generating gaseous SiF in the reaction process₄And H₂Absorbing tail gas such as O and the like by potassium hydroxide solution;

(4) naturally cooling the prepared yttrium lutetium fluoride to room temperature under the protection of argon;

the obtained rare earth lutetium yttrium fluoride has the purity of 99.999 percent and the oxygen content of 72ppm by analysis, and can be used for preparing rare earth alloy.

Example 4

The embodiment provides a method for preparing rare earth fluoride from scintillation crystal waste, which specifically comprises the following steps:

(1) 500g of lutetium silicate scintillation crystal waste is crushed and sieved by a 100-mesh sieve, and then is washed for 3 times by 50L of deionized water and filtered;

(2) then putting the mixture into a vacuum drying smelting furnace, and keeping the temperature of 600 ℃ for vacuum drying for 10 hours;

(3) putting the dried powder into a high-purity graphite crucible of a fluorination reaction furnace, introducing mixed gas of dry HF gas and Ar gas in a volume ratio of 1:10 to react for 12 hours at 1000 ℃ to generate gaseous SiF₄And H₂Absorbing tail gas such as O and the like by a sodium hydroxide solution;

(4) naturally cooling the prepared lutetium fluoride to room temperature under the protection of nitrogen;

the prepared rare earth lutetium fluoride has the purity of 99.99 percent, the yield of 99.2 percent and the oxygen content of 65ppm, and can be used for preparing high-purity metal or laser crystals.

Comparative example 1

The difference from the example 1 is that the mixed gas in the step (3) does not contain nitrogen, and the prepared rare earth lutetium fluoride has the purity of 98.52%, the yield of 97.1% and the oxygen content of 80 ppm.

Comparative example 2

The difference from the example 1 is only that the volume ratio of the hydrogen fluoride gas to the inert gas in the mixed gas in the step (3) is 0.1:3, and the prepared rare earth lutetium fluoride has the purity of 99.91 percent, the yield of 98.3 percent and the oxygen content of 335 ppm.

Comparative example 3

The only difference from example 1 is that the temperature of the treatment was 500 deg.C, and the rare earth lutetium fluoride was prepared with a purity of 99.69%, a yield of 98.8%, and an oxygen content of 266 ppm.

Comparative example 4

The only difference from example 1 is that the temperature of the treatment was 1200 deg.C, and the rare earth lutetium fluoride was prepared with a purity of 98.12%, a yield of 96.5%, and an oxygen content of 90 ppm.

Comparative example 5

The only difference from example 1 is that the treatment time was 5 hours, and the rare earth lutetium fluoride was prepared with a purity of 98.60%, a yield of 97.3% and an oxygen content of 525 ppm.

As can be seen from the results of the above examples and comparative examples, the method provided by the invention realizes the efficient preparation of the rare earth fluoride by controlling the gas composition of the reaction and the reaction conditions, and the purity of the obtained rare earth fluoride is more than or equal to 99.99%, and the rare earth fluoride can be used for preparing high-purity metal or laser crystal. The invention not only recovers the rare earth elements, but also forms new high-added-value high-purity rare earth fluoride, thereby not only meeting the requirements of saving rare earth resources and reasonably utilizing the rare earth resources, but also reducing the environmental pollution and meeting the requirements of environmental protection.

The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be understood by those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, additions of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.

In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.