CS260921B1 - Method of dihydrogen phosphates or/and ammonium hydrogen phosphate production with reduced fluorine content - Google Patents

Abstract

The essence of the method is that in an aqueous medium at a temperature of to the boiling point of the reaction mixture, preferably at 70 to 90 ° C, bring the phosphoric acid into reaction raw material obtained by ammonia extraction phosphoric acid and superphosphate and after precipitation of the fluoride ion into the desired the solid is separated from the suspension phase and the remaining solution is worked up to the desired product. The product is suitable as mineral feed compound additive.

Description

The invention relates to a process for the production of ammonium dihydrogen phosphate or dibasic phosphate or mixtures thereof with reduced fluorine content.

The fluorine-reduced ammonium phosphates based on the trihydrogenphosphoric acid extract are most often produced by recrystallization. Some methods involve purifying hydrogen fluoride from hydrogen fluoride by distillation. Methods of converting water-soluble forms of fluorine to calcium fluoride are also proposed.

The disadvantage of the production methods used hitherto 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. Distillation of the distillation apparatus is greatly distilled when hydrogen fluoride is distilled off from trihydrogenphosphoric acid.

Methods based on converting water-soluble fluorine compounds to calcium fluoride are technologically more complex than the proposed manufacturing process.

According to the invention, these disadvantages are solved by a process for the production of ammonium dihydrogen phosphate or dibasic phosphate or mixtures thereof with reduced content of fluorine, which consists in bringing into the aqueous medium at a temperature up to the boiling point of the reaction mixture, preferably 70 to 90 ° C. Phosphorous feedstock obtained by ammoniaization of the trihydrogenphosphoric acid and single or double or triple superphosphate, or a mixture of these superphosphates, and after precipitation of the fluoride ions to the desired degree, the solid phase is separated from the suspension and the remaining solution is worked up.

Phosphoric acid and calcium and / or calcium-magnesium feedstock are preferably used instead of some or all of the superphosphate.

Instead of some or all of the superphosphate, it is preferable to use natural phosphate and trihydrogenphosphoric acid and / or a mineral acid or a mixture thereof.

Instead of some or all of the superphosphate, a water-soluble calcium and / or magnesium salt or salt mixture is preferably used.

Instead of some or all of the superphosphate, a sodium phosphate salt or a mixture of salts is preferably used.

In the case of the phosphorus feedstock and / or superphosphate and / or the substitute feedstocks and possibly also in the reaction mixture, the pH is preferably adjusted either by adding trihydrogenphosphoric acid and / or by ammonia and / or alkaline calcium and / or magnesium and / or alkaline containing phosphorus.

The reaction mixture and / or the remaining solution after filtration is preferably concentrated by evaporation of water, then the solid phase is separated and the remaining solution is worked up to the product.

After precipitation of the fluoride ions and separation of the solid phase, the residual solution is preferably purified by crystallization.

Phosphoric acid is preferably added to the solution remaining after separation of the solid phase.

The solution remaining after separation of the solid phase to adjust the composition is preferably ammoniacalized.

The solution remaining after separation of the solid phase is preferably ammoniacalized in order to reduce the calcium and / or magnesium content, and the resulting precipitate is separated from the resulting suspension and processed, for example, into calcium and / or magnesium phosphate feed material.

The solution remaining after separation of the solid phase is preferably converted by reaction with a soluble calcium and / or magnesium feedstock, for example, to a calcium and / or magnesium feedstock.

Part or all of the wash water is preferably returned to the process.

Part or all of the mother liquor, in the case of processing the remaining solution by crystallization, is preferably returned to the process.

The basic effect of the process according to the invention is that the reduction of the fluorine content to the value required for feed purposes is not achieved by a very simple technology.

In addition, all phosphorus, except technological losses, is used from the feedstock to produce the desired product. 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, a stoichiometric or substoichiometric amount of amophos relative to the fluoride ion content is added to the superphosphate suspension after optionally adjusting the pH. It is preferred that the reaction be conducted at higher temperatures, preferably at 70 to 90 ° C. After the fluoride ions have precipitated to the desired degree, the solution is separated, for example by filtration, from the solid phase and worked up to the desired product.

The production method of the invention is described in more detail below with reference to specific embodiments.

He did

150 L of water was heated to 80 ° C in a batch stirred tank reactor, then 20 kg of simple granulated superphosphate made from Kola apatite was added, and after 15 minutes of stirring, gradually increasing the temperature to 95 ° C, 80 kg of amophos was added. After 30 minutes, the suspension was pumped onto a filter, the separated solution was evaporated to give a salt containing approximately 88 wt% ammonium dihydrogen phosphate, 10 wt% ammonium hydrogen phosphate and 0.1 wt% fluorine.

Example 2

The experiment was carried out as in Example 1 except that the fluorine-reduced ammonium salt solution was crystallized to a solid salt. The crystals contained 0.065 wt% fluorine.

Example 3

The experiment was carried out as in Example 1 except that 10 kg of simple superphosphate and 4.1 kg of calcium chloride were used for defluorination. After heating for 20 minutes, the suspension was filtered and the solution was evaporated to a solid salt containing 0.1 wt% fluorine.

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

Claims (10)

A process for the preparation of a fluorine-reduced dibasic phosphate and / or ammonium hydrogen phosphate, characterized in that, in an aqueous medium at a temperature of up to the boiling point of the reaction mixture, preferably at 70 to 90 ° C, the phosphorous raw material obtained by ammonia trihydrogenphosphoric acids and a single, double or triple superphosphate, or any mixture of these superphosphates and / or a component consisting of an acidic trihydrogenphosphoric and calcium and / or calcium-magnesium raw material and / or a component consisting of natural phosphate and trihydrogenphosphoric acid and / or a mineral acid or (a) a water-soluble calcium salt and / or a magnesium salt, and / or a phosphorous salt probe or a mixture of these salts and / or a raw material comprising these salts and a water-soluble calcium and / or magnesium salt. Process according to claim 1, characterized in that the pH of the phosphorous raw material and / or superphosphate or of the substitute raw materials and, optionally, in the reaction mixture, is adjusted by adjusting the pH by addition of phosphoric acid and / or ammonia and / or alkaline calcium; (a) a magnesium feedstock and / or an alkaline phosphorus-containing feedstock. 3. Process according to claim 1, characterized in that the reaction mixture and / or the remaining solution after filtration is concentrated by evaporation of water, then the solid phase is separated and the remaining solution is worked up into the product. 4. A process according to any one of claims 1 to 3, characterized in that after the fluoride ion has precipitated and the solid phase is separated off, the remaining solution is purified by crystallization. 5. A process according to any one of claims 1 to 4, wherein phosphoric acid is added to the solution remaining after the 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 ammoniaised to adjust the composition. 7. A process according to any one of claims 1 to 6, characterized in that the solution remaining after the solid phase separation is ammoniacalized to reduce the calcium and / or magnesium content, and the resulting precipitate is separated from the suspension and processed, for example, into calcium and / or magnesium feed material. 8. A process as claimed in any one of claims 1 to 7, wherein the solution remaining after the solid phase separation is converted by reaction with a soluble calcium and / or magnesium feedstock into, for example, lime and / or magnesium feedstock. 9. The process according to claims 1 to 8, characterized in that some or all of the washing water is returned to the process. 10. The process of claims 1 to 9, wherein some or all of the mother liquor is returned to the process when the remaining solution is crystallized.