RU1820886C - Process for preparing composite fluorides - Google Patents

Abstract

The dry recrystallized nitric salts of barium and lanthanum or strontium and lanthanum are mixed with a 5-fold excess of 40-41% hydrofluoric acid, after settling, the precipitate is separated, washed with hydrofluoric acid and ethyl alcohol, dried at 80-100 ° C and calcined at 400-500 ° C in the presence of ammonium fluoride in a charge ratio of:. 348aF2-5LaF3 or 34SrF2-5LaF3 products suitable for the manufacture of fluoride glass are obtained. 1 s.p. crystals, 3 tab.

Description

The invention relates to inorganic chemistry, and in particular to a technology for producing complex fluorides used to produce fluoride glass in fiber optics.

An object of the invention is to provide a product suitable for the manufacture of fluoride glass.

The essence of the method is as follows: dry recrystallized nitric salts of barium, strontium and lanthanum, react with 40-41% hydrofluoric acid to form double fluorides, and due to excess HF, the product is further purified.

PRI me R. Dry recrystallized barium nitrate salts in an amount of 88.74 g or strontium 71.74 g and lanthanum in an amount of 21.65 g are placed according to stoichiometry in a fluoroplast-4 reactor. Pour a 5-fold excess of stoichiometrically necessary 40-41% hydrofluoric acid grade sec in the amount of 165.7

g ml for barium fluoride and 167.1 ml for strontium fluoride. Excess HF is taken to completely precipitate the double fluorides and to remove them from the trace metals. The mixture is mixed with a mechanical stirrer also from fluoroplast-4 for 5-6 hours. The complete deposition and purification of fluorides occurs during this time. After settling, the mother liquor is decanted, the precipitate is washed repeatedly with a 3% solution of hydrofluoric acid to remove MOS ions 2 times with ethyl alcohol to speed up the drying time and obtain a free-flowing powder. The product is dried at 80-100 ° C with an infrared lamp. Drying at this temperature allows mainly alcohol and water to be removed. Below 80 ° C, the drying process lengthens for up to 48 hours. When the temperature rises above 100 ° C, the product will sinter, lose flowability, and the particle size becomes large. After drying, the double fluorides are calcined at 350-400 ° C in the presence of ammonium fluoride in the ratio Mefz MeF3: NH4F 1: 1. You00

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31820886 4

the required calcination temperature is necessary 400 ° C is necessary to completely remove the scum to completely remove the gaseous HF. the gaseous HF.

Table 1 lists the main parameters. At temperatures below 350 ° C, for example

of the inventive method. 330 ° C, removal of gaseous НР-process After calcination, the composition of double fluorine-5 is slow and incomplete. Experimentalda is analyzed by chemical, but it is substantively proved that at calcination temperature

trace metals are detected at 330 ° C; traces of HF remain in fluorides and

spectral methods. The content of the products corresponds to the composition (mol.%).

microimpurities in products (in May.%) at EXAMPLE 1.34VaP2 0.5NR-51 aPz 0.5HF.

given in Table 2.10 Example 2.34SrFjr 0.5HF-5LaF-0.5HF.

Selection of 40-41% Hydrogen Fluoride-Calcination at 400 ° C

hydrochloric acid based on the formation of complex makes it possible to obtain products corresponding to fluorides in the anhydrous state. If you are responsible for the composition, (mol.%):

concentration of hydrofluoric acid-P Example 1.34ВаРзН51аРз.

you are below 40%, for example 34, then the product is half-15 EXAMPLE 2.343gP2-51 aPz.

studied in hydrated state. At higher temperatures,

In this case, the water content ranges from 0.8 to for example 430 ° C, partial pyro1.0 mole is observed. Concentrations of at least 41% are hydrolyzed, which is confirmed by the derivative which makes the experiment difficult due to a specific study.

higher vapor pressure of HF in solution. 20 g of Table 3 shows the given compositions

During the synthesis, it was found that double fluorides suitable for the manufacture of complete deposition of fluorides, as well as for the gelation of fluoride glass, and the compositions of elemental filling from the components of t-t obtained by this method are double

of ferrous metals, a five-fold of fluorides is required,

an excess of hydrofluoric acid. 25 Thus, this method allows reacting to obtain very pure reaction time. finely crystalline components less than 5 hours, for example 4 hours, the bifurcated powder of double fluoride fluorides does not correspond to the indicated composition 34BaF2-5LaF3 and 24SrF2-5LaF3, which are compositions. Elemental analysis of fluorides is sometimes the starting materials for the following (mol%) .30 manufacture of fluoride glass.

Example 1.30BaF2 3HF-4LaF3-3HF. Formula of the Invention

Example 2.30 SrF2 vHF-4LaFa 3HFi1. A method for producing fluorides was possible by lengthening the holding time of the composition, including processing the mixture for more than 6 hours, the chemical composition of the product remains the salts of the corresponding metals fluoride-unchanged. 35 with hydrogen acid with stirring

At a selected drying temperature of 80, the reaction mixture is settled, separating 100 ° С from the products (Example 2), the precipitate is removed from the solution, and the precipitate is washed

alcohol and water. If the products are dried first, a solution of hydrogen fluoride

is carried out at a temperature below 80 ° C, for example, an acid, and then an organic solvent 70 ° G, then the process of drying the extension is 9 lem, the product is dried and calcined, it lasts 12 hours, cfleAOBafeflbHO takes place and so that, in order to ensure

additional contamination of the double fluorine possibilities of the preparation of the product; . for the manufacture of fluoride glass, in

as salts take dry, previously

When the double fluorides are dried45, recrystallized, nitric acids at a temperature of 70 ° C in the products leave barium and anthane, or strontium and lanthanum traces of HF. Chemical analysis of fluorides by treatment of a mixture of salts is carried out at 40-41%, which follows the following Compositions. Hydrofluoric acid followed by Example 1.34BaF2 1.5HF-5LaFa 1.5HF. Other exposure of the reaction mixture to Example 2.34SrF2-1.5HF-5LaF3 1.5HF .50 nye5-6h.

With increasing drying temperature, 2. The method according to claim 1, distinguishing cabbage soup and with

for example, up to 120 ° C, the products are sintered, so that drying is carried out at 80-100 ° C, they lose their flowability and become lumpy, and calcining is carried out at 350-400 ° C in the presence of ammonium fluoride at a mass ratio of In this way, it was shown 55 a mixture of salts and ammonium fluoride that the chosen temperature of calcination 350 is 1: 1.

Table 1

table 2

Table 3