CS260873B1 - Method of calcium salts production with low solubility - Google Patents

Description

The invention relates to a process for the production of low-solubility calcium salts or mixtures thereof.

For the sake of simplicity, the widespread processes for producing the above-mentioned highly pure products are precipitation processes. The starting materials used are mostly highly pure chemicals, which are specially formulated for this purpose.

Thus, as is evident, the lack of precipitation methods used so far lies primarily in the fact that the production of high-purity feedstocks places a heavy burden on the production economy. In addition, very difficult to process by-products are very often formed. This disadvantage is overcome by the process according to the invention for the production of low-solubility calcium salts or mixtures thereof, which comprises reacting the soda produced by the ammonia process with ammonia recovery from sodium hydroxide liquor, containing predominantly calcium chloride, a cation-containing feedstock. sodium and anion of bicarbonate and carbonate and / or hydroxyl and an acid containing anion appropriate for the manufacture of the desired salt, or / and this acid partially neutralized with a sodium cation feedstock and / or bicarbonate and / or carbonate and / or hydroxyl, the precipitate formed is separated and processed product, wherein the remaining solution containing predominantly sodium chloride and / or the resulting carbon dioxide is partially or completely returned to the soda production.

Instead of some or all of the calcium chloride solution resulting from the recovery of ammonia from sodium hydroxide solution, also containing sodium chloride, this solution or suspension is used, after concentration and / or after concentration and reduction of the sodium chloride content.

Instead of the feedstock containing sodium cation and anionic bicarbonate and carbonate and / or hydroxyl, a solution resulting from the production of pure sodium carbonate and / or any of its derivatives and / or sodium bicarbonate, or mixtures thereof, is used.

Preferably, stabilizers are added to retard dehydration of the calcium salt hydrates with low solubility or the hydrolysis of the anhydrous salts.

The basic effect of the process according to the invention is that by combining the production of calcium salts of low solubility with the production of soda, a waste-free technology is achieved which makes it possible to utilize all

And the raw materials to produce the desired product. Furthermore, in the production of soda, the production of a waste solution containing mainly calcium chloride is reduced and sodium chloride is saved. As a result, the process according to the invention becomes considerably more economical than the known processes.

The manufacture may be continuous, discontinuous, or a combination of both. For example, the reaction solution is reacted in the production of soda by an ammonia process resulting from the recovery of ammonia from the sodium hydroxide solution, containing predominantly calcium chloride, the sodium cation feedstock and the bicarbonate and carbonate anion, and the acid containing anion appropriate to produce the desired salt. The resulting precipitate is collected, for example by filtration or centrifugation, washed and worked up to the desired product. The remaining solution containing predominantly sodium chloride and / or the resulting carbon dioxide is partially or completely returned to the soda production. The wash water can be incorporated into the production cycle. It is advantageous to add the additives which dehydrate the calcium salt hydrates or the hydrolysis of the anhydrous salts to the solutions to be precipitated and / or directly to the precipitation apparatus and / or to the dry or wet product and / or to the particle size adjustment by milling.

The production method according to the invention is described in more detail below with reference to a specific embodiment.

Example 1 liter of waste solution resulting from the recovery of ammonia from sodium hydroxide solution, containing predominantly calcium chloride and a stoichiometrically equivalent amount of 75% by weight of trihydrogen phosphoric acid. in a batch stirred reactor was transferred with a solution containing 5 wt. % sodium carbonate and 5 wt. sodium bicarbonate to precipitate dibasic calcium phosphate dihydrate, which was collected by filtration, washed and dried at 45 ° C. The reaction temperature did not exceed 30 ° C.

The product obtained is suitable for use in the cosmetic, food, pharmaceutical, electrotechnical industries and as an enrichment of compound feed in animal production.

Claims (1)

Subject A process for the production of low-solubility calcium salts or mixtures thereof, comprising reacting a soda produced by the ammonia process resulting from the recovery of ammonia from sodium hydroxide solution, containing predominantly calcium chloride, a sodium cation-containing feedstock and a bicarbonate anion; carbonate and / or hydroxylic acid and an anionic acid appropriate for the production of the desired salt, or / and this acid partially neutralized with a sodium cationic feedstock and anionic bicarbonate and / or carbonate and / or hydroxyl, the resulting precipitate is collected and processed to give the product a solution containing predominantly sodium chloride and / or the resulting carbon dioxide is partially or totally returned to the soda production or may be used in other processes.