SU709537A1 - Method of preparing calcium fluoride - Google Patents

Description

(54) METHOD OF OBTAINING FLUORINE CALCIUM

one

This invention relates to a method for producing calcium fluoride.

A known method for producing calcium fluoride by reacting soluble fluoride salts with calcium carbonate with the addition of oleic acid to increase the filtration rate 1.

The disadvantage of this method is the addition of oleic acid.

There is also known a method for producing calcium fluoride by reacting potassium fluoride solution with calcium hydroxide, separating the wet sludge by filtration, drying the latter, briquetting and calcining 2.

The disadvantage of this method is the low filtration rate (1.22-1.52 t / m2 h) and the relatively low strength of the briquettes (10-12 kg / cm).

The aim of the invention is to increase the filtration rate of calcium fluoride and increase the strength of the briquettes.

The goal is achieved by the fact that according to the proposed method of obtaining calcium fluoride calcium hydroxide is taken in excess of 0.5-7% of stoichiometry, and briquetting

lead in the presence of a wet precipitate in a ratio.

An excess of calcium hydroxide serves as a binder during briquetting and at the same time increases the filtration rate of calcium fluoride. An increase in the excess of calcium hydroxide by more than 7% is economically inexpedient; moreover, calcium hydroxide, remaining in the product, reduces its quality. A decrease in excess calcium hydroxide of less than 0.5% does not give a positive effect.

Example 1. To obtain 388 g of briquetted calcium fluoride, 427 g of calcium hydroxide was added to 4420 g of a solution of potassium fluoride with a content of 15% K1 heated to 60 ° C, while cooTBeTcfByeT had a 0.5% excess of the stoichiometric norm, while continuously mixing for 1 hour. The resulting suspension is filtered and washed with 1750 ml of hot water. Speed

filtration of the pulp in the filtrate is 2.2 t.

Claims (2)

The moisture content of the resulting precipitate is 29%. A part of this sediment is dried in an oven at 110 ° C and after drying it is mixed with a wet precipitate in a ratio of 4, i.e. 101.5 g of dry calcium fluoride and 406 g of wet sediment. From the resulting mass | spring) cylindrical briquettes weighing 25 g and diameter 30 .mm, pressing pressure 10kOg / cm dried briquettes at 120 ° C for 2 Briquette strength after drying 20 kg / cm, residual moisture i, 3Vo. Example 2. To obtain 331 g of briquetted calcium fluoride, 243 g of calcium hydroxide was added to 3714 g of a heated potassium fluoride solution with a content of 13.4% KF, which corresponds to 3.5% of the stoichiometric excess, with continuous stirring. The resulting suspension is filtered and washed with hot water. The filtration rate of the pulp in the filtrate is 2.3 t / m. The moisture content of the obtained precipitate is 29.3%. A portion of this precipitate is dried in an oven at. and after drying, mix with a wet sediment in the ratio i: 3, i.e. 105 g of dry CaF and 314 g of wet sludge. From the resulting mass, cylindrical briquettes weighing 25 g and a diameter of 30 mm are pressed, the pressing pressure is 100Kr / tM and the briquettes are dried for 2 hours at 120 ° C. The strength of briquettes after drying is 20 kg / cm 2, the residual moisture is 1.1%. Example 3. To obtain 331 g of briquetted calcium fluoride, 243 g of calcium hydroxide was added to 4068 g of a heated potassium fluoride solution with a content of 11.8% KF, which corresponds to 7% of the stoichiometric excess, with continuous stirring. The resulting suspension is filtered and washed with hot water. The filtration rate of the null by the filtrate is 2.65 t / cm. The moisture content of the obtained precipitate is 32.8%. A part of this sediment is dried in a drying cabinet Cree 110 ° C, after drying it is mixed with a wet precipitate in a ratio of 1: 5, i.e. 75 g of dry calcium fluoride and 375 g of wet sediment. From the resulting mass, cylindrical briquettes weighing 25 g and a diameter of 30 mm are pressed, the pressing pressure is 100k; / s1 the briquettes are dried at 120 ° C for 2 h. The briquette strength after drying is 15 kg / cm -, the residual moisture is 1.2%. Claims method of producing calcium fluoride by reacting potassium fluoride solution with calcium hydroxide, separating wet sediment by filtration, drying the latter, briquetting and calcining, in order to increase calcium fluoride filtration rate and briquette strength, calcium hydroxide is taken in excess of 0 , 5-7% of stoichiometry, and briquetting is carried out in the presence of a wet precipitate in the ratio: 3d5. Sources of information taken into account during the examination 1. USSR author's certificate No. 109043, cl. From 01 F 11/22, 1956. 2. Zelikin M. B., Bakulina A. L. Proceedings of NIOHIM, 10, 1957, p. 111 (prototype).