SU1058958A1 - Method for producing anhydrous protonated ammonium tripolyphosphate - Google Patents

Description

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This invention relates to a process for the production of polyphosphates, in particular, ammonium acid tripolyphosphate, described by the formula (NH4) 9H {P3Oio) i and containing two nutrients (nitrogen and phosphorus) necessary for plant nutrition. The synthesized compound is used in agrochemistry, as a possible component of solid ammonia polyphosphoric fertilizers. This compound can be used in agriculture as an easily assimilable highly concentrated complex fertilizer, as an additive to a fertilizer for leveling its composition in terms of nutrient content, as an additive to synthetic detergents. Thermal methods for obtaining pure (anionic) composition (NM4) 9H (P30i (,) 2 are not described in the lyrethrutine).

A known method for producing dehydrated- ,. ammonium phosphates in the heat treatment of mono ammonium phosphate in an atmosphere of ammonia under a pressure of 1.5-15 atm and 00-450 C. This removes most of the water and changes the anionic composition of the resulting products, approaching the composition of high molecular polyphosphates of the type The product contains 16.5-17.9% i NHs, 71.5-72% PzOs from mix 36.5-39.0% water-soluble 1.

However, this method is unsuitable for obtaining anhydrous polyphosphate (MH4) 9H (PzO) o) 2 since it decomposes at the indicated temperatures, and in addition, the method involves carrying out the process at high ammonia pressures.

The closest to the invention to the technical essence and the achieved result is a known method of obtaining anhydrous protonated ammonium tripolyphosphate

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by thermal dehydration of its dihydrate. According to this method, the dihydrate is heat treated in vacuum (hPa) and in temperature range 46-70 0. The final product is investigated by methods: thin-layer chromatography, chemical and X-ray phase analysis 12

The disadvantages of this method are that the dehydration stage of (NH4) H (P30jo) 2 2HjQ is accompanied by both deammonization processes and anion destruction. The final sample contains not more than 52-86% of phosphorus in the form of; tripolyphosphate; the pH formed (NN4) (PzOi Q) j crystallizes only in mixture with other phosphate phases; due to the accumulation of loose P-OH groups, the dehydrated final product loses its initial flowability.

The purpose of the invention is to increase the content of PjOj in the form of tripolyphosphate in the product used as a complex, ballast-free azo-phosphorus fertilizer.

The goal is achieved in that according to the method of producing anhydrous protonated ammonium tripolyphosphate by heat treatment of its dihydrate, the dihydrate is heat treated in a stream of dry ammonia in two stages, and in the first and second stages the process is carried out at 100-125 and 125-180 ° C and speed, 5 and 0.2-0.3 l / min, respectively.

Ammonia at the first and second stages is served at the rate of 10-11 and 1.5-2 May. hours on May I including the original dihydrate accordingly.

In tab. 1 and 2 show the dependences of the degree of dehydration (ip) and the phosphorus content in the form of tripolyphosphate (P3) on the ammonia (V) feed rate during the dehydration of the dihydrate at each stage of the process;

T a b l i c a 1 100

0.6

51 96

88

89

89 90

97

97

T C

V, l / min

:%;% p,% Carrying out the process in stage 2 reduces the total consumption of ammonia. For example, if the dehydration is carried out in one stage at: 130-140 ° C, the consumption of ammonia increases by approximately one and a half times, and at higher temperatures even more, and, moreover, the Final product contains PgP in the form of Tripolyphosphate, more than 95%. The supply of ammonia is carried out in such a way that "its consumption in the 1st stage is 10-11 parts by weight, n4 1 weight. including dihydrate, and on the 2nd 1.5-2 paddle. PRI me R 1. Immerse 1 g of crystalline hydrate (NH4) H (P30jо) in the reactor and feed 10 g of dry ammonia at a rate of 0.5 l / min at 100 ° C. In the second stage of the process, the temperature is raised to 130 ° C and 1.5 g of ammonia are fed at a rate of 0.2 l / min. In the resulting product found 22.9% NHj 61.1%

table 2

Continuation of the table, 2 PjOs.Phosphorus content in the form of tripolyphosphate 96%. According to analysis data, the resulting product is co (OH4) 9H (PZO, o) 2. Example 2. 1 g of the dihydrate {MH4) 9H (PzO1o) 2 2 HjО is immersed in the solution, the air is forced out: with a flow rate of ammonia and at 120 ° С 1.1 g of dry ammonia are fed with a speed of 0.5 l / mich. In the second stage of the process, the temperature is raised up to 180 ° С and 2.0 g of ammonia are fed at a rate of 0.2 l / min. In the resulting product found 23% NHj, 62.8% PjOj. According to this analysis, the resulting product is SrBOI (MH4) 9H (Pz01o) g. Carrying out the process according to the method proposed allows to obtain a product with the content of PjOs in it in the form of tripolyphosphate 1.5-2 times higher than that of the prototype.

Claims (2)

1. METHOD FOR PRODUCING AN Anhydrous Protonated TRIPOLYPHOS-FATA AMYONIA. By heat treatment of its dihydrate, the distinguishing feature is that, p. In order to increase the content of Р ₂ О ₅ in the form of tripolyphosphate in the product used as a complex ballast-free nitrogen-phosphorus fertilizer, the heat treatment of dihydrate is carried out in a stream of dry ammonia in two stages, and at the first and second stages the process is carried out at 100–125 and 125-180 ° С and ammonia is fed at a rate of 0.4-0.5 and 0.2-0.3 l / min, respectively. 2. The method according to π. 1, characterized in that the ammonia in the first and second stage serves at the rate of 10-11 and 1.5-2 may. hours for 1 part by weight starting dihydrate, respectively. SL 00: from