阅读说明：本技术 一种高纯氟化镁光学材料制备方法 (Preparation method of high-purity magnesium fluoride optical material ) 是由 李雪 马亚丽 岳岩 曹笑宁 刘云义 于 2020-11-20 设计创作，主要内容包括：一种高纯氟化镁光学材料制备方法,一种光学材料制备方法,首先将轻烧粉与铵盐按一定比例配成溶液进行蒸氨反应,将得到的氨气通入一定浓度的氢氟酸进行固化,然后将制得的氟化铵溶液与蒸氨得到的镁盐溶液加入到聚四氟乙烯容器中,在充分搅拌的情况下,控制反应温度于一定范围内进行结晶反应,反应一定时间且反应液pH值为7～10左右,恒温陈化1～4 h后进行过滤、洗涤及干燥得到高纯氟化镁。滤液中铵盐可用于蒸氨反应,实现铵盐的循环使用。本发明所得产品纯度高,质量好,原料来源丰富,操作简便,设备占地面积小,生产成本低,污染物排放量小,适宜于规模生产,是制备光学材料高纯氟化镁的一种技术。(The preparation method of the high-purity magnesium fluoride optical material comprises the steps of firstly preparing solution from light burning powder and ammonium salt according to a certain proportion, carrying out ammonia evaporation reaction, introducing obtained ammonia gas into hydrofluoric acid with a certain concentration for solidification, then adding the prepared ammonium fluoride solution and magnesium salt solution obtained by ammonia evaporation into a polytetrafluoroethylene container, controlling the reaction temperature to carry out crystallization reaction within a certain range under the condition of fully stirring, carrying out reaction for a certain time, enabling the pH value of reaction liquid to be about 7-10, ageing at constant temperature for 1-4 h, and then filtering, washing and drying to obtain the high-purity magnesium fluoride. Ammonium salt in the filtrate can be used for ammonia distillation reaction, so that the recycling of the ammonium salt is realized. The product obtained by the invention has high purity, good quality, rich raw material sources, simple and convenient operation, small occupied area of equipment, low production cost and small pollutant discharge amount, is suitable for large-scale production, and is a technology for preparing high-purity magnesium fluoride of optical materials.)

1. The preparation method of the high-purity magnesium fluoride optical material is characterized by comprising the following preparation processes: mixing light calcined powder as raw material with ammonium salt solution, performing ammonia distillation reaction to obtain magnesium salt solution and ammonia gas, removing impurities to obtain magnesium salt refined solution (MgO + NH)₄ ⁺ → Mg²⁺ + NH₃↑ + OH^-) (ii) a Absorbing the ammonia gas with hydrofluoric acid to obtain ammonium fluoride solution (HF + NH)₃ = NH₄F) (ii) a Adding the solution into a crystallization reactor, introducing a magnesium salt refining solution under a stirring state, heating the reaction solution to perform double decomposition reaction, controlling the reaction conditions, and after the reaction, performing constant-temperature aging, filtering, washing and drying on the reaction solution to obtain the high-purity magnesium fluoride crystal (Mg) of the optical material²⁺ + 2NH₄F → MgF₂↓ + 2NH₄ ⁺) (ii) a The ammonium salt solution in the filtrate is recycled for the first step of reaction through crystallization reaction, so as to realize ammoniumAnd (4) recycling the salt.

2. The method for preparing a high-purity magnesium fluoride optical material according to claim 1, wherein the method uses light calcined powder as a magnesium source.

3. The method for preparing a high-purity magnesium fluoride optical material according to claim 1, wherein the ammonium salt is one or a combination of any several of ammonium nitrate, ammonium chloride, ammonium sulfate and organic ammonium salt (ammonium acetate).

4. The method for preparing a high-purity magnesium fluoride optical material according to claim 1, wherein the solid-phase light calcined powder is reacted with a liquid-phase ammonium salt solution by ammonia distillation to prepare a refined magnesium salt solution.

5. The method for preparing a high-purity magnesium fluoride optical material as claimed in claim 1, wherein the ammonia gas generated by the ammonia evaporation reaction becomes a raw material for the magnesium precipitation crystallization reaction through the solidification of hydrofluoric acid.

6. The method for preparing the high-purity magnesium fluoride optical material according to claim 1, wherein the ammonia evaporation reaction temperature is 90-120 ℃, and the reaction time is 2-5 h; the concentration of the magnesium salt refining liquid is 1-4 mol/L.

7. The method for preparing a high-purity magnesium fluoride optical material as claimed in claim 1, wherein the filtrate obtained after filtering out the magnesium fluoride product is subjected to crystallization reaction to realize recycling of ammonium salt.

Technical Field

The invention relates to a preparation method of an optical material, in particular to a preparation method of a high-purity magnesium fluoride optical material.

Background

The ultraviolet optical technology is widely used in the fields of laser confinement nuclear fusion, photoetching machines, ultraviolet optical processing, medical treatment, third-generation semiconductor ultraviolet packaging and the like, but the lack of high-performance ultraviolet high-transparency optical materials has become a technical bottleneck restricting the development of ultraviolet lasers and deep ultraviolet light sources. The reason is that the current ultraviolet materials are mainly ultraviolet-grade fused quartz and calcium fluoride crystals, but the defects such as color centers and the like are easily caused by the action of quartz and ultraviolet light, and the problems of difficult growth and double refraction of high-quality calcium fluoride crystals cause that the performances of the calcium fluoride crystals cannot completely meet the use requirements. And the high-performance and large-size fused quartz and calcium fluoride used in China are mainly imported from European and American areas, the novel ultraviolet lens material is developed, the foreign technology blockade is broken through, and the unique technical scheme and technical advantages in China are urgently formed. Magnesium fluoride crystals, which exhibit excellent transmittance and low refractive index from vacuum ultraviolet 110 nm to infrared 7.5 μm, so that the loss of light refraction is very low, are the only crystals with both wide spectral transmission range and birefringent properties, and are used for manufacturing optical components such as windows, mirrors, lenses, polarizers, wedges and substrates, and cowlings (caps) of aeronautical (astronomical) instruments (such as missiles), and are also essential elements of lithography machines in integrated circuit manufacturing. The optical fiber product made of magnesium fluoride reduces signal loss by 2 orders of magnitude compared with the quartz material, and is considered as the next generation optical fiber material.

As a high-end functional magnesium chemical, the production of optical materials magnesium fluoride requires high purification and crystallization of the product. When the magnesium fluoride crystal product is used for manufacturing missile fairing, the purity of the magnesium fluoride crystal product needs to be more than 99.9 percent; when the method is used for a laser lens of a photoetching machine, the purity of the laser lens is even required to be more than 99.99%, and the impurity types of the laser lens are strictly limited. At present, domestic magnesium fluoride product production enterprises face a big problem that the purity of products is difficult to meet the requirements or stable production cannot be realized due to the insufficient system solution refining technology in product production.

Disclosure of Invention

The invention aims to provide a preparation method of a high-purity magnesium fluoride optical material, which respectively takes hydrofluoric acid, light burning powder and ammonium salt as raw materials, ammonium fluoride prepared by solidifying ammonia gas by the hydrofluoric acid and magnesium salt solution prepared by reacting ammonia distillation are subjected to magnesium precipitation reaction in a polytetrafluoroethylene container to prepare a high-purity magnesium fluoride product, the ammonia gas is solidified by the hydrofluoric acid to reduce the emission of ammonia, the ammonium salt raw material can be obtained from magnesium precipitation filtrate through the crystallization process, the recycling of ammonium salt is realized, and the effects of reducing cost and reducing pollutant emission are achieved.

The purpose of the invention is realized by the following technical scheme:

a preparation method of a high-purity magnesium fluoride optical material comprises the following preparation processes: mixing light calcined powder as raw material with ammonium salt solution, performing ammonia distillation reaction to obtain magnesium salt solution and ammonia gas, removing impurities to obtain magnesium salt refined solution (MgO + NH)₄ ⁺ → Mg²⁺ + NH₃↑ + OH^-) (ii) a Absorbing the ammonia gas with hydrofluoric acid to obtain ammonium fluoride solution (HF + NH)₃ = NH₄F) (ii) a Adding the solution into a crystallization reactor, introducing a magnesium salt refining solution under a stirring state, heating the reaction solution to perform double decomposition reaction, controlling the reaction conditions, and after the reaction, performing constant-temperature aging, filtering, washing and drying on the reaction solution to obtain the high-purity magnesium fluoride crystal (Mg) of the optical material²⁺ + 2NH₄F → MgF₂↓ + 2NH₄ ⁺) (ii) a And recycling the ammonium salt solution in the filtrate for the reaction in the first step through crystallization reaction to realize circulation of the ammonium salt.

According to the preparation method of the high-purity magnesium fluoride optical material, the light calcined powder is used as a magnesium source.

According to the preparation method of the high-purity magnesium fluoride optical material, the ammonium salt is one or a combination of any several of ammonium nitrate, ammonium chloride, ammonium sulfate and organic ammonium salt (ammonium acetate).

According to the preparation method of the high-purity magnesium fluoride optical material, the solid-phase light-burned powder and the liquid-phase ammonium salt solution are subjected to ammonia distillation reaction to prepare the refined magnesium salt solution.

According to the preparation method of the high-purity magnesium fluoride optical material, ammonia gas generated in ammonia distillation reaction is solidified into a raw material for magnesium precipitation crystallization reaction through hydrofluoric acid.

According to the preparation method of the high-purity magnesium fluoride optical material, the ammonia evaporation reaction temperature is 90-120 ℃, and the reaction time is 2-5 hours; the concentration of the magnesium salt refining liquid is 1-4 mol/L.

According to the preparation method of the high-purity magnesium fluoride optical material, the filtrate after the magnesium fluoride product is filtered out is subjected to crystallization reaction to realize recycling of ammonium salt.

The invention has the advantages and effects that:

1. the light calcined powder with low cost is used as a magnesium source, the mother liquor of the product after reaction is easy to filter and wash, and the purity of the magnesium fluoride product is very high.

2. The reaction is completed under the conditions of mild temperature (lower than 100 ℃) and pressure (basically normal pressure), the operation steps are simple, and the crystallization process can be well controlled. Strong acid is not used in the reaction process, and no by-product is generated, thereby reducing the production cost and the external environmental pollution.

3. Ammonium salt can be recovered from the product filtrate by utilizing the crystallization process to realize ammonium salt circulation. Further improving the economic benefit of the process and reducing the emission of pollutants.

4. The preparation method developed by the invention can synthesize high-quality and high-purity magnesium fluoride products, has simple operation steps, less required equipment and occupied area, less energy consumption, low equipment investment and production cost, less pollutant discharge amount and is suitable for large-scale production.

Drawings

FIG. 1 is an SEM photograph (200 times magnification) of the crystal shape of magnesium fluoride;

FIG. 2 is an SEM photograph (magnified 3000 times) of the crystal shape of magnesium fluoride;

figure 3 is a XRD characterization of the product.

Detailed Description

The present invention will be described in detail with reference to the embodiments shown in the drawings.

The invention relates to a preparation method of high-purity magnesium fluoride of an optical material, which takes light-burned powder as a raw material to be mixed with ammonium salt solution with certain concentration, ammonia evaporation reaction is carried out under certain conditions to prepare magnesium salt solution with certain concentration and ammonia gas, and then refined magnesium salt solution (MgO + NH) is obtained by removing impurities₄ ⁺ → Mg²⁺ + NH₃↑ + OH^-). Using a certain concentration of hydrofluoric acidAbsorbing the ammonia gas to prepare an ammonium fluoride solution (HF + NH)₃ = NH₄F) In that respect Adding the solution into a crystallization reactor, introducing a magnesium salt refining solution under a stirring state, heating the reaction solution to a certain temperature for double decomposition reaction, controlling the reaction conditions, after reacting for a certain time, performing constant-temperature aging, filtering, washing and drying on the reaction solution to obtain the high-purity magnesium fluoride crystal (Mg) of the optical material²⁺ + 2NH₄F → MgF₂↓ + 2NH₄ ⁺). And recycling the ammonium salt solution in the filtrate for the reaction in the first step through crystallization reaction to realize circulation of the ammonium salt.

The method takes the low-price light calcined powder as a magnesium source, thereby reducing the production cost of the high-purity magnesium fluoride product of the optical material.

The ammonium salt is one or the combination of any more of ammonium nitrate, ammonium chloride, ammonium sulfate and organic ammonium salt (ammonium acetate, etc.). The solid-phase light calcined powder and the ammonia distillation reaction of the liquid-phase ammonium salt solution are used for preparing the refined magnesium salt solution, so that the introduction of insoluble impurities is reduced, and the purity of the magnesium fluoride product is improved. The ammonia gas generated in the ammonia distillation reaction becomes a raw material for magnesium precipitation crystallization reaction through the solidification of hydrofluoric acid, thereby reducing the emission of the ammonia gas. The filtrate of the crystallization reaction of the ammonium fluoride and the refined magnesium salt solution contains a large amount of strong acid and weak base ammonium salt, so that the aggregation of alkaline metal ions in a magnesium fluoride product can be reduced, and the purity of the product is improved. The ammonia distillation reaction temperature is 90-120 ℃, and the reaction time is 2-5 h; the concentration of the magnesium salt refining liquid is 1-4 mol/L. The purity content of the prepared magnesium fluoride crystal is more than 99.9 percent, the chroma reaches colorless and transparent large crystal, the melting point is 1260 ℃, and no collapse point exists. The filtrate after the magnesium fluoride product is filtered out can realize the recycling of ammonium salt through crystallization reaction.

Example 1

Preparing ammonia gas and a magnesium nitrate solution with the mass concentration of about 1.0 mol/L by taking light calcined powder and ammonium nitrate as raw materials, introducing hydrofluoric acid into generated ammonia gas for solidification to prepare an ammonium fluoride solution with a certain concentration, adding the magnesium nitrate solution obtained by ammonia evaporation into 50 mL of glycol solvent, carrying out reflux treatment for 8 hours under stirring at 60 ℃, dropwise adding the prepared ammonium fluoride solution into the solution under stirring for 35 minutes, and stirring for 7 hours after dropwise adding is finished to obtain liquid sol; then standing and aging at 140 ℃ for more than 12 h to obtain solid gel; aging for 1-4 h at constant temperature, and then filtering, washing and drying; and drying at 160-180 ℃ for more than 12 h, and finally roasting in a muffle furnace at 400-500 ℃ for more than 4 h to obtain the high-purity magnesium fluoride. Ammonium salt in the filtrate can be used for ammonia distillation reaction, so that the recycling of the ammonium salt is realized.

Example 2

Preparing a magnesium chloride solution with ammonia gas and substance concentration of about 1.2 mol/L by taking light calcined powder and ammonium chloride as raw materials, dissolving magnesium chloride and polyethylene glycol in 80 mL of ethylene glycol, carrying out reflux treatment for 8 h under stirring at 40 ℃, then dropwise adding an ammonium fluoride aqueous solution (70 wt%) into the solution under stirring, wherein the dropwise adding time is 35 min, and then stirring for 7 h after the dropwise adding is finished to obtain a liquid sol; then standing and aging at 110 ℃ for more than 12 h to obtain solid gel; aging for 1-4 h at constant temperature, and then filtering, washing and drying; and drying at 140 ℃ for more than 12 h, and finally roasting in a muffle furnace at 400-500 ℃ for more than 4 h to obtain the high-purity magnesium fluoride.