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A method for preparing high-purity calcium fluoride in ethanol system

A technology of pure calcium fluoride and calcium fluoride, applied in the direction of calcium/strontium/barium fluoride, calcium/strontium/barium halide, etc. Raw material reaction rate and other issues, to achieve the effect of enhancing dispersion performance, improving washing and filtration performance, and avoiding gelation

Inactive Publication Date: 2016-11-30
湖南有色金属投资有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, no matter calcium hydroxide, calcium carbonate or calcium chloride is used as raw material, affected by the reactivity and reaction rate of the raw material during the reaction, the new solid-phase calcium fluoride generated will always form a precipitate on the solid raw material, thereby affecting The reactant is coated to affect the reaction rate of the raw material
In the system where solid-liquid reaction forms a new solid phase, although the coating phenomenon can be reduced, it is difficult to avoid, so the prepared calcium fluoride can not meet the requirement of not less than 99.9% of high-purity calcium fluoride; while liquid-phase synthesis The calcium fluoride particles produced by the reaction are extremely fine, making it difficult to filter and wash the product, increasing the impurity content, and making it difficult to realize industrial production

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] (1) Preparation of calcium chloride solution: Weigh 38.8g (0.35mol) of anhydrous calcium chloride and add it to 72.1g of ethanol-water mixed solution with a volume ratio of 1:1, stir and dissolve to obtain chlorine with a mass concentration of 35wt%. Calcium solution;

[0023] (2) Crystallization reaction: Add 7.8g (0.1mol) of large-grained calcium fluoride seed crystals (20-40 mesh in particle size) to the calcium chloride solution obtained in step (1), and simultaneously add 246.7g of it with a mass concentration of 15wt% ammonium fluoride solution (ammonium fluoride content 1mol), control the stirring speed to 250r / min, the feeding time is 0.5h, after the feeding is completed, continue to stir and react for 1h to obtain a suspension;

[0024] (3) Filtration and washing: Vacuum filter the suspension obtained in step (2), and then wash and filter with 1L of hot water at 60°C to obtain a calcium fluoride filter cake;

[0025] (4) Drying and burning: put the calcium flu...

Embodiment 2

[0027] (1) Preparation of calcium chloride solution: Weigh 44.4g (0.4mol) of anhydrous calcium chloride and add it to 66.6g of ethanol-water mixed solution with a volume ratio of 1:1, stir and dissolve to obtain chlorine with a mass concentration of 40wt%. Calcium solution;

[0028] (2) Crystallization reaction: Add 15.6g (0.2mol) large-grained calcium fluoride seed crystals (40-60 mesh in particle size) to the calcium chloride solution obtained in step (1), and simultaneously add 185.0g dropwise at a mass concentration of 20wt% ammonium fluoride solution (ammonium fluoride content 1mol), the stirring speed is controlled to 300r / min, the feeding time is 0.5h, and the stirring reaction is continued for 1h after the feeding is completed to obtain a suspension;

[0029] (3) Filtration and washing: Vacuum filter the suspension obtained in step (2), then wash and filter with 1L of hot water at 70°C to obtain a calcium fluoride filter cake;

[0030] (4) Drying and burning: put the ...

Embodiment 3

[0032] (1) Preparation of calcium chloride solution: Weigh 49.9g (0.45mol) of anhydrous calcium chloride and add it to 61.0g of ethanol-water mixed solution with a volume ratio of 1:1, stir and dissolve to obtain 45wt% calcium chloride Calcium chloride solution;

[0033] (2) Crystallization reaction: Add 19.5g (0.25mol) of large-grained calcium fluoride seeds (60-80 mesh in particle size) to the calcium chloride solution obtained in step (1), and drop 148.0g of it at a mass concentration of 25wt% at the same time ammonium fluoride solution (ammonium fluoride content 1mol), control the stirring speed 300r / min, feed time 1h, continue to stir and react for 2h after the feed is completed, to obtain a suspension;

[0034] (3) Filtration and washing: Vacuum filter the suspension obtained in step (2), and then wash and filter with 1L of 80°C hot water to obtain a calcium fluoride filter cake;

[0035] (4) Drying and burning: put the calcium fluoride filter cake obtained in step (3) ...

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Abstract

The invention relates to a method for preparing high-purity calcium fluoride in an ethanol system. The method comprises the following steps: (1) preparing a calcium chloride solution, namely dissolving calcium chloride in a mixed solution of ethanol and water to obtain a calcium chloride solution; (2) carrying out a crystallization reaction, namely adding large-particle calcium fluoride crystal seeds into the calcium chloride solution obtained in the step (2) and dropwise adding an ammonium fluoride solution, and after feeding, stirring to react to obtain a turbid liquid; (3) filtering and washing, namely filtering the turbid liquid obtained in the step (2) and then washing by hot water and filtering to obtain a calcium chloride cake; and (4) drying and firing, namely drying the calcium chloride cake obtained in the step (3) and then firing, and crushing the firing product to obtain high-purity calcium fluoride powder. The main content of a high-purity calcium fluoride product prepared by the method is greater than or equal to 99.9%, the impurity content is less, the demand on an optical filming material is satisfied, the problem that calcium chloride particles are fine and hard to filter in a conventional preparation method is solved, and the yield of calcium chloride is greater than or equal to 96%.

Description

technical field [0001] The invention relates to a method for preparing calcium fluoride, in particular to a method for preparing high-purity calcium fluoride in an ethanol system. Background technique [0002] Calcium fluoride crystal is a colorless and transparent fluorite-type cubic structure single crystal, which has excellent optical properties, high light transmission performance and excellent refractive index in the range from infrared to extreme ultraviolet Performance and chemical stability are also very good. Therefore, calcium fluoride is not only an ideal material for dark-field imaging systems, but also an indispensable material for manufacturing large-scale integrated circuit lithography equipment lenses. In the range from visible light to ultraviolet light, calcium fluoride crystals have special refractive index and relative dispersion value, have excellent chromatic aberration compensation ability, and can be used to manufacture apochromatic lenses. [0003]...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F11/22
Inventor 李程文廖志辉王子龙刘东晓段立山
Owner 湖南有色金属投资有限公司
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