CS257373B1 - Production method of melt of condensated ammonium phosphate - Google Patents

Abstract

The solution relates to a method for producing a melt condensed ammonium phosphates resulting from high temperature neutralization phosphoric acid with ammonia. Continuously] high temperature neutralization with ammonia is subjected to a hot reaction product phosphorous acid with phosphorus oxides arising from the combustion of elemental phosphorus. For each part of phosphorus pentoxide into the process in the mold phosphoric acid is metered into the reaction 0.02 to 0.80 parts by weight of elemental phosphorus and 0.14 to 0.44 wt ammonia.

Description

The invention relates to a process for the production of a melt of condensed ammonium phosphates by simultaneous high temperature neutralization and dehydration of phosphoric acid, or solutions of acidic ammonium phosphates in phosphoric acid, with ammonia gas.

The melt of polycondensated ammonium phosphates of the formula (NH 4) _m H _{(n + 2)} -πιΡηθ3η + 1] is one of the basic starting materials for the preparation of concentrated multicomponent clear and suspension liquid fertilizers, detergents, thickeners, flame retardants, corrosion inhibitors and also some additives used in textile refinement.

Several methods of melt preparation of polycondensated ammonium phosphates are currently known. The most elaborate and widespread are the methods based on atmospheric pressure or vacuum neutralization of polyphosphorus so-called. % of superphosphoric acids with ammonia, or methods based on the reaction of trihydrogenphosphoric acids of varying concentration and purity with concentrated ammonia.

The classical production processes are based on neutralization of polyphosphorus, so-called. of superphosphoric acid (H _{n + 2} P _n O _{3 n +} i) with ammonia. A number of various modified production methods of this kind include, for example, the processes described in U.S. Pat. no. 3,484,192, 3,537,814, 3,572,990, 3,645,674, 3,687,618, 3,544,298, 3,676,101,

(+420) 734 708, 3 775 534, 3 939 255, 3 947 261,

950,495 and 4,011,300.

Although melt of condensed ammonium phosphates (KFAj for the first time on an industrial scale had been prepared in 1957 at WEST KENTACKY LIQUID FERTILIZER COMPANY in Hopkinsville (USA) in connection with the preparation of liquid fertilizer type 11—33—0, the vast majority of manufacturers of phosphate-phosphate liquid fertilizers of the polyphosphate type still use in their preparation processes based on neutralization of polyphosphoric acid, so-called superphosphoric acid by ammonia water or ammonia gas. The process of production of KFA by neutralization of polyphosphoric acid by ammonia can be simplified as follows:

1st stage - preparation of polyphosphorus, so-called. of suiperophosphoric acid by thermal dehydration of trihydrogenphosphoric acid t

η H3PO4 ---- ►

H _{n + 2} P _n O 3 _n + 1 + (n - 1 H ₂ O

2nd stage - neutralization of polyphosphoric acid

H _{n + 2} P n O _{3 n + 1} + m NH 3 ---->

* (NH 4) mH (n + 2) -ηιΡηθ3η + 1 or

H ' ₊₂ P _n O _{3 n + 1} + m (NH ₃ .H ₂ Oj --- * (NH 4) m H (n + 2) -ιηΡηθ3η + 1 "t IUHžO.

At present, about 70 production plants in the USA, 7 large-scale units in the USSR and at least 4 plants in France produce liquid fertilizer of 10-34-0 type from superphosphoric acid, prepared by concentrating purified H3PO4 produced by so-called H3PO4. wet method - extraction H3PO4.

The basis of more modern and especially recently expanding melt production processes of polycondensated ammonium phosphates is high-temperature neutralization and simultaneous dehydration of trihydrogenphosphoric acids (H3PO1) with concentrated ammonia.

The simultaneous neutralization and molecular dehydration of the reaction mixture can be illustrated by the reaction scheme:

η H 3 PO 4 + m NH 3 ---->

—► (NH 4 _{m m} H _{(n + 2)} _ _m P _n O _{3 n + 1} -j- (n-j- ₁ H f).

Among the many inventions in the field, for example: USA Pat. no. 3,382,059, 3,375,063, 3,420,624, 3,464,808, 3,723,086, 3,503,706,

(+420) 649 175, 3 650 727, 3 788 817, 3 554 728,

(+420) 562 778, 3 677 734, 3 733 191, 3 949 058,

041 133, 3,540,874, 3,446,581, 3,492,087,

539,327, 3,502,441, 3,917,475, 3,988,140 a

104 362, French Pat. no. 1 493 803 and 2 009 787, MS. author's certificate no. 180,802, 199,819, 205,849, 210,335 and 216,856.

Although both types of process allow melt preparation of polycondensory ammonium phosphates, their industrial use is usually complicated mainly due to either of the following disadvantages:

- processes of the first type are energy intensive and their use requires the use of special construction materials as well as special and costly machinery;

- the technologies underlying the processing of trihydrogenphosphoric acid usually do not provide products of the same quality as those based on polyphosphoric processing, the so-called polyphosphoric acid process; and often also do not guarantee the same level of operational reliability.

In the past period, the molecular dehydration of monophosphates in the presence of urea or thiourea, which serve as a condensing agent, has been studied by several authors. Processes of this type are the subject of, for example, the following inventions:

USSR Author Certificate No. 420 602 (1974); 2,308,408 (1974),

925,068, (1969), 1,228,593, (1963), DAS no.

198 335; Japanese Pat. 47-30,033 (1972), 39,960 (1969), 46-37,664 (1974); French patents no. 1,533,272 (1968),

Nos. 461,027 (1966), 1,471,510 (1967), 1,437,486 (1966), U.S. Pat. 3,397,035 (1968),

586,495 (1971), 3,495,937 (1970), 3,419,349 (1968); Belgian patents no. 674 161 (1966), 677 866 (1966) and British patent no. 1,182,395 (1970).

Processes based on the dehydration capacity of sulfur oxides or products of polymerization or hydration reactions, respectively. combinations of their use together with urea or thiourea are the subject of MS. of the author's certificate no. 237,462 and 249,214.

It has now been found that the melt of condensed ammonium phosphates can be prepared according to the present invention. It is an object of the invention to produce a melt of condensed ammonium phosphates formed by high temperature neutralization of extractive phosphoric acid, or a mixture thereof with thermal phosphoric acid ammonia. The method is characterized in that a continuous high-temperature neutralization with ammonia, while simultaneously dehydrating the reaction mixture, is subjected to a combustion reaction product of phosphoric acid with phosphorus oxides, which are formed during the burning of elemental phosphorus. In this case, 0.02 to 0.80 parts by weight of elemental phosphorus and 0.24 to 0.44 parts by weight of ammonia are fed into the reaction for each part by weight of phosphorus pentoxide fed in the form of extractive phosphoric acid or a mixture thereof with thermal phosphoric acid. The advantage of the proposed method of melt production of condensed ammonium phosphates compared to previously known production methods is in particular the fact that the heat of reaction released during phosphorus burning (Qij and hydration by the reaction of phosphorus pentoxide (Q2) is economically utilized. technology of inorganic leanings, Izd. Khimija, Moscow 1975 is Qi = 24 310 kj / kg of phosphorus and Q2 = 3,274 kj / / kg of phosphorus, which will result in reduced raw material demands or improved quality of products produced on the basis of condensed ammonium phosphates.

The process for producing a melt of condensed ammonium phosphates is apparent from, but not limited to, the following examples.

Example 1

To model a laboratory tube reactor were fed approximately 60 g / min extracting orthophosphoric acid containing 52.04% of P2O3 temperature of about 20 ^D C approximately 2.16 g / min of molten white phosphorus at a temperature of 75 to 80 DEG C., about 1.2 times the the excess air compared to the stoichiometry of the equation P 1 + 5 O 2 -> 2 P 2 O 3. The resulting steam-liquid mixture at 142-167 ° C was neutralized with gaseous ammonia, which was fed to the reactor at an average of 123.5 g / min. A melt of the following composition was formed at a temperature of 228-242.5 ° C:

total content P2O5 - 62,32% total content N - 11,92%

P2O5 content in condensed form -

59.8% of total P2O5.

Example 2

An average of 36 g / min of extraction H3PO4 containing 52.04% P2O3, an average of 22 g / min of thermal H5PO1 containing 56.88% P2O5, an average of 138 g / min was fed at room temperature (approx. H2O, an average of 24.5 g of molten white phosphorus at a temperature of 75-80 ° C and an average of 0.16 m ³ / min of air, and the vapor-liquid mixture formed at 158-173 ° C formed by the reaction heat was neutralized with gaseous ammonia at a temperature of 259 to 288 ° C, the melt formed had the following composition:

total P2O5 content - 64.08% total N content - 11.88% P2O5 content in condensed form - 68.1%

The melt prepared above was used (by dissolving in H2O with NH3) to prepare a liquid fertilizer of the type 10-34-0 having the following composition:

total content N - 10,18% total content P2O5 - 34,35% proportion of P2O5 in condensed form - 62,0% pH (1% aqueous solution) - 6,42 density - 1,41 g / cm ³

Example 3

An average of 180 g / min of I-DPOt containing 55.88% / P2O5 at a temperature of about 20 ° C was fed to a modeling device according to Examples 1 and 2, on average

2.5 g / min molten white phosphorus at 75-70 ° C and 0.013 m ³ / min air. The resulting vapor-liquid mixture at a temperature of 138-146 ° C was neutralized with ammonia at a rate of 39.5 g / min. Melting of the following composition was prepared at a temperature of 198-215 ° C:

total P2O5 content - 58.2% total N content - 10.6% P2O5 content in condensed form - 41.3%

Claims (1)

Process for producing a melt of condensed ammonium phosphates formed by high temperature neutralization of extractive phosphoric acid, or a mixture thereof with thermal phosphoric acid ammonia, characterized in that the continuous high-temperature ammonia neutralization under simultaneous dehydration of the reaction mixture with the phosphoric acid reaction , which arise from the burning of elemental phosphorus, for each part by weight of phosphorus pentoxide fed into the process in the form of extractive phosphoric acid or a mixture thereof with thermal phosphoric acid, 0.02 to 0.80 parts by weight of elemental phosphorus and 0.24 are added to the reaction. up to 0.44 parts by weight of ammonia.