CS274152B1 - Method of ammonium dihydrogen phosphate production - Google Patents

Abstract

Ammonium phosphate raw material is dissolved in water, the solid residue is separated and the solution is transformed by heating into a solid product that can be further heated. During the process pH can be modified by trihydrogen phosphoric acid or ammoniac. The gaseous phase can be freed of fluoric compounds by condensation or washing. The product is suitable as a mineral additive for feeding mixes.

Description

The present invention relates to a process for the production of ammonium phosphate monobasic or in admixture with a fluorine-reduced ammonium phosphate.

The reduction of the fluorine content of the ammonium phosphoric salt or a mixture thereof based on trihydrogenphosphoric acid extraction is most often carried out by recrystallization or by converting the water-soluble fluorine compounds to low-solubility and filtering them off.

The disadvantage of the production methods used so far is mainly that, in recrystallization, the reduction of the fluorine content is generally not sufficient for some purposes. In addition, there is also considerable loss of the desired product in the mother liquor. Processes based on converting water-soluble fluorine-containing compounds to sparingly soluble are technologically more complex in terms of complex feedstock utilization.

According to the invention, these processes are solved by a process for the production of ammonium phosphate monobasic or in admixture with a fluorine-reduced ammonium phosphate from an ammonium phosphorous raw material based on trihydrogenphosphoric acid extract, which comprises dissolving ammonium phosphate in water or dissolved ammonia and / or trihydrogenphosphoric acid, and / or ammoniacalization is carried out during dissolution and / or ammonium phosphates are dissolved after dissolution of the ammonium phosphates, and / or trihydrogenphosphoric acid is added, the solid residue is separated as necessary and the solution is heated to a solid product. the gas phase may be partially or completely freed of fluorine compounds and / or ammonia and / or dust fractions, for example by condensation and / or water, and / or with a solution and / or suspension containing calcium and / or magnesium compounds, and / or containing an ammonium phosphate salt or any mixture of these salts, and / or containing an alkaline feedstock.

According to a further feature of the invention, the solution is concentrated after removal of the solid residue, crystallizing to give a solid salt, which is reduced to a volatile fluorine compound by heating to at least 60 ° C.

According to another aspect of the invention, the solid salt crystals are ground before and / or during defluorination.

According to a further feature of the invention, part of the fluoride ions is removed by means of calcium and / or magnesium and / or calcium-magnesium raw materials in the preparation of a solution which is further processed by heating or crystallization and heating to the product.

According to a further feature of the invention, phosphoric acid is added to the solution remaining after solid phase separation to adjust the composition.

According to a further feature of the invention, the solution remaining after the solid phase is separated is ammoniaised to adjust the composition.

According to a further feature of the invention, some or all of the washing water is returned to the process.

According to a further feature of the invention, part or all of the solution or suspension resulting from the purification of the gas phase is returned to the process.

According to a further feature of the invention, the suspension is heated in preparation for filtration.

The basic effect of the process according to the invention is that the reduction of the fluorine content is achieved by a very simple process. In addition, all of the phosphorus in the feedstock is utilized to produce the desired product. As a result, the production method according to the invention becomes more economical than the previously known production methods.

The manufacture may be continuous, discontinuous, or a combination of both.

For example, the ammonium phosphate salt is dissolved in water, preferably at a higher temperature, and the solid residue is separated by filtration. The solution is further converted by heating, for example in a spray drier, to a solid product which is optionally further heated. The gaseous phase can be freed of fluorine compounds, possibly ammonia and dust by a water scrubber.

The process according to the invention is described in more detail below with reference to specific examples.

Example 1

302.5 g of amophos were dissolved in 600 ml of water at 80 ° C. The resulting suspension was filtered and dried at boiling point and further heated at 150 ° C. The product was predominantly ammonium dihydrogen phosphate with a fluorine content below 0.15% by weight.

Example 2

The process was conducted as in Example 1 except that the outgoing gas phase was purified by water scrubbing.

The product is suitable as a mineral additive for compound feed.

Claims (10)

SUBJECT OF THE INVENTION A process for the production of ammonium phosphate, optionally in admixture with a fluorine-reduced ammonium phosphate from an ammonium phosphorous feedstock produced on the basis of trihydrogen phosphoric acid, characterized in that the ammonium phosphate feedstock is dissolved in water or water containing dissolved ammonia and / or acid Phosphoric trihydrogen and / or ammoniacalization is carried out during dissolution and / or ammonium phosphate is dissolved after dissolution of the ammonium phosphates, and / or phosphoric acid is added, the solid residue is separated as necessary, the solution is heated to a solid product, optionally further heated. partially or totally free of fluorine compounds and / or ammonia and / or dust fraction, for example by condensation and / or water, and / or with a solution or suspension containing calcium and / or magnesium compounds, and / or with an ammonium phosphate salt; and any mixtures of these salts and / or containing an alkaline feedstock. 2. The process according to claim 1, wherein the solution is optionally concentrated after removal of the solid residue, crystallizing to obtain a solid salt, wherein the content of volatile fluorine compounds is reduced by heating to at least 60 ° C. 3. The process according to claim 1, wherein the solid salt crystals are ground prior to and / or during defluorination. 4. Process according to claim 1, characterized in that part of the fluoride ions is removed by means of calcium and / or magnesium and / or calcium-magnesium raw materials in the preparation of a solution which is further processed by heating or crystallization and heating to the product. 5. A process as claimed in any one of claims 1 to 4, wherein phosphoric acid is added to the solution remaining after solid phase separation. 6. A process according to any one of claims 1 to 5, wherein the solution remaining after the solid phase is separated is ammoniacalized to adjust the composition. AND 3 CS 274152 Bl 7. A method according to any one of claims 1 to 6, wherein some or all of the washing water is returned to the process. 8. The process according to claim 2, wherein some or all of the mother liquor is returned to the process in the case of the remaining solution being crystallized. 9. A process according to any one of claims 1 to 8, wherein some or all of the solution or suspension resulting from the purification of the gas phase is returned to the process. 10. The method of items 1 to 9. characterized in that the suspension is heated in preparation for filtration.