SU1126542A1 - Method for producing aluminium trifluoride - Google Patents

Abstract

A method for the production of aluminum trifluoride, including the treatment of aluminum hydroxide with hydrofluoric acid, crystallization, filtration and dehydration calcination, is therefore, for the purpose of improving the quality of the product, hydrofluoric acid is used in amounts of 115120% of stoichiometry and dehydration calcination is carried out at 450-495 °.

Description

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4 SUBJECT The invention relates to a method for producing high-purity alcumin trifluoride, which is used in the electronics industry, in optical glassmaking, where aluminum fluoride is subjected to increased requirements for the content of the main substance in the target product at the level of 99.5% by weight. The known method of producing aluminum trifluoride by treating hydrated alumina with hydrofluoric acid followed by crystallization of AlFj crystalline hydrate, its filtration and dehydration prodol ij. However, to prevent the process of high-temperature hydrolysis during calcination, the hydrated aluminum fluoride is subjected to treatment with sodium hydroxide or sodium carbonate, which necessitates the introduction of an additional stage (calcination stage) and at the same time does not provide the product of the required quality, and the final product is contaminated with fluoride sodium to 4%. The closest to the proposed technical essence and the achieved result is a method for producing aluminum trifluoride, which includes the treatment of aluminum hydroxide with hydrofluoric acid, crystallization, filtration and dehydration calcination. In this case, the dehydration of aluminum fluoride is carried out in two stages. In the first stage, the A1P „.5H2O hemihydra is obtained; in the second stage, the complete dehydration of the product is achieved due to its slow heating in a rotary kiln at 500 ° Cе2. The disadvantage of this method is the low quality of the target product, since the content of hydrated water in it is at the level of 4%. The purpose of the invention is to increase the quality of the product. This goal is achieved in that according to the method of producing aluminum trifluoride, which includes the treatment of aluminum hydroxide with hydrofluoric acid, calcination, calcination, filtration and dehydration cord, hydrofluoric acid is used in an amount of 115-120% of stoichiometric, and dehydration calcination is performed at 450-495 ° C. Excess of hydrofluoric acid in the product at 450-495 C interacts with hydrofluoric acid formed by the reaction of Al-F (eH) j, -I-2HF A1P3 +, + HF AlF +, which contributes to an increase in the content novnogo substance in the product (99.5%). The dosage of hydrofluoric acid less than 115% of the stoichiometrically necessary increases the amount of unreacted aluminum fluoride, which leads to a decrease in the content of the basic substance in the target product. Dosage of hydrofluoric acid more than 120% of stoichiometrically necessary is impractical due to the fact that the content of the basic substance in the product does not change significantly, and the yield of the finished product decreases. At a temperature, the reaction of the low-temperature fluorination slows down a little, as a result, the time of heat treatment increases dramatically and the efficiency of the process as a whole decreases. Increasing the temperature limit above 495 ° C economically; impractical. . Example. 81.1 mol (1460 g) of demineralized water and 41.96 mol (839.31 g) of 45% aqueous hydrofluoric acid solution are poured into a fluoroplastic reactor equipped with a thermostatted jacket and a mixing device. 5.36 mol are added with continuous stirring. (418 g) aluminum hydroxide. The dosage of hydrofluoric acid required for stoichiometry is 117.5% by weight. The interaction of the loaded reagents is accompanied by the release of heat. The temperature in the reactor is maintained at 93-97 seconds. The crystallisation is carried out at this temperature. The suspension is cooled and filtered. The resulting crystalline trifluoride aluminum calcined at. Thus, the required content of the basic substance in the target product is reached up to 99.5% by weight. Preparation of aluminum trifluoride c. Examples 2-6 are carried out in a similar manner. The test results are presented in-table. From the table it can be seen that at a calcination temperature of 450-495 0, it is possible to increase the content of the basic substance in the target product from 96 to 99.5 wt.%, While the dosage of hydrofluoric acid is 115-120% of the stoichiometric required. The use of aluminum fluoride in optical glassmaking with a basic substance content of 99.5%

allows to improve the quality of optical glasses.

. Alcmini trifluoride, obtained by the method prototype, is similar to the product manufactured with the brand

net price list price is 3 rubles. 80 kopecks per 1 kg, and the price of the product obtained by the proposed method is the qualification of OSh 3 40 rubles for 1 kg.

Note: “The content of microimpurities in examples 1-6, wt.%: Fe 5 .1 (Co 2-10; N1 IlO Cr 210 Cu S-lfl, and in the prototype Fe 510. -E

Claims (1)

METHOD FOR PRODUCING ALUMINUM TRIFLUORIDE, including treatment of aluminum hydroxide with hydrofluoric acid, crystallization, filtration and dehydration calcination, which is different because, in order to improve the quality of the product, hydrofluoric acid is used in an amount of 115120% of the stoichiometrically necessary, and dehydration rolling is carried out at 450-495 ° C.