SU42054A1 - A method of obtaining photonic sodium - Google Patents

Description

At present, sodium fluoride, which is necessary for impregnation of sleepers and in the production of cryolite, is obtained by the acidic or alkaline method. To obtain pure sodium fluoride by the acid method, fluoride-hydrogen acid, completely free of silica, is required. Production of which from the spar of our deposits, containing a significant amount of silica, is difficult to achieve and the loss of fluorine in the form of silicofluoride compounds.

By the alkaline method, i.e., by fusing spar with soda, sodium fluoride free from silica can be obtained, but this method requires relatively high grade spar, not less than 85% CaFs, and the use of spar is only 50-55%. In addition, sodium fluoride is obtained in the form of a 4% solution, therefore, in order to obtain a dry product, 24 tons of water must be evaporated per tonne, which greatly increases the cost of the final product. Finally, due to the precipitation of the salt during the evaporation on the heating surfaces, the evaporation is greatly complicated and the fuel consumption increases.

The proposed method of obtaining silica-free fluoride of sodium from low-grade fluoride state without the cost of soda required when the above alkaline and acid

(130)

The method is as follows. The finely ground spar of the proposed method is processed by heating with a solution of aluminum sulphate. According to the equation

 (ZOOZ + 2 CaFo L 2p4504 + 2 CaSOi

poorly soluble gypsum and soluble compound AlsFiSO are formed, containing fluorine in the form of a complex.

Accompanying fluorspar silica, due to the binding of fluorine with aluminum to the complex, does not go into solution at all.

The solution of this compound is separated from gypsum, strongly evaporated, then ammonia is added to the alkaline reaction and the mixture of hydrate and ammonium sulphate obtained in this way in a furnace at a temperature of 450-550 ° is treated with a stream of water vapor and ammonia. In addition, Scordozo hydrate decomposes into alumina and hydrogen fluoride, which with ammonia produces ammonium fluoride and, together with sulfuric acid ammonium, is removed from the furnace by a continuous stream of steam. The ammonium fluoride obtained in this way is introduced into a saturated, heated salt solution.

The solubility of sodium fluoride in water is very small, and in the presence of table salt is significantly reduced,

as a result, upon the introduction of ammonium fluoride into sodium chloride solution, sodium fluoride precipitates and an ammonium chloride solution is formed (100 g of water dissolve 37 g of ammonium chloride at a temperature of 20 ° -78 2.

After otfenturizing, the excreted sodium fluoride mother liquor, from which the remaining small amount of sodium fluoride can be precipitated by adding sulfuric acid aluminum in the form of cryolite, is treated with caustic lime in order to release ammonia from ammonium chloride and return it to production.

Thus, low-grade fluorspar without the consumption of soda produces pure solid fluoride, which does not require pre-evaporation, and after centrifugation it contains only 30–40% moisture, which is easy to remove by simple drying.

The subject matter of the invention.

A method of producing sodium fluoride, characterized in that gaseous products are obtained in a solution of sodium chloride, which are obtained by applying water vapor and ammonia at a temperature of 450-500 ° C on fluorhydro-alumina.