CS199819B1 - Method of producing polycondensed ammonium phosphates for preparing concentrated liquid multicomponent fertilisers - Google Patents

Description

The invention relates to a process for the production of a melt of polycondensated ammonium phosphates by ammoniacalization and dehydration of finely divided orthophosphoric acid of different purity and concentration, as well as a finely atomized mixture of this acid and ammonium phosphates, Ammonia can be used, in particular, as an intermediate for the production of concentrated liquid multicomponent fertilizers.

Liquid, especially multicomponent fertilizers have many significant advantages over solid multicomponent fertilizers.

For example, in actual technology, the costs of drying, granulation and surface treatment are eliminated. Storage is not associated with the risk of sintering, is easier to apply, requires less manpower than when applying solid fertilizer, and is more convenient in terms of work. Further, when handling liquid multicomponent fertilizers, the problems associated with the mixing of the individual components are eliminated and the application can achieve a higher uniformity of distribution on the ground, which often causes considerable difficulties in solid multicomponent fertilizer mixtures. Despite the above mentioned advantages, the types of liquid multicomponent fertilizers produced in the past had some disadvantages. At relatively high production costs, the maximum concentration of nutrients in clear liquid multicomponent fertilizers ranged from 32 to 34%, since at higher concentrations it can reach99819

199 819 resulted in the excretion of crystals or maturation. Other problems and difficulties were associated with the corrosion of production, storage and application equipment.

Over the past 10 to 15 years, decisive progress has been made in overcoming these disadvantages of liquid multicomponent fertilizers.

One of the basic starting materials for the preparation of concentrated liquid multicomponent fertilizers is the tavenipa of polycondensed ammonium phosphates of the general formula:

(NH 4) _m H ( _{n +} 2) -. _m P _n θ3η + 1 where n = number of P atoms bound in the chain / so-called. degree of polycondensation / Si = number of hydrogen atoms replaced per polycondensated phosphate molecule.

From the melt of polycondensated ammonium phosphates it is possible to prepare so-called. basic NP solutions usually of the composition 10-34-0 or 11-37-0, which can be used or as a two-component NP liquid fertilizer, or after their addition with potassium component and after treatment of nitrogen with urea or ammonium nitrate, if necessary to prepare solid clear or suspension liquid multicomponent fertilizers of the composition 7-21-7; 9-9-9j 6-12-6. 15-15-15 ·· 10-30-10, 10-20-20, 12-18-18 as well as other types.

Despite the higher concentration of nutrients in the basic clear NP-solutions based on polycondensated phosphates, these may have relatively high low temperature stability compared to the orthophosphate-based NP solutions. In addition, polycondensated phosphates have significant macaque / sequestering capabilities and therefore allow the preparation of clear liquid multicomponent fertilizers from which the solid phase, although these, in addition to the impurities coming from at least the extractive phosphoric acid, also contain trace elements.

In principle, efforts to master the technology of liquid multicomponent fertilizers prepared on the basis of polycondensated ammonium phosphates can be divided into two basic groups.

An older, technologically advanced, and now largely widespread, USA is the production of melt of polycondensated ammonium phosphates, respectively. direct preparation of the base NP-solution by neutralization of polyphosphoric 'Superphosphoric acid (a mixture of orthophosphoric acid and polycondensated phosphoric acids), ammonia gas or an aqueous solution thereof. . Prephosphoric acid is prepared prior to this process or from thermal phosphoric acid and P ₂ 0, - or by concentration of orthophosphoric acid produced by so-called phosphoric acid. by a wet process (decomposition of the phosphates by mineral acids), which is also called extraction phosphoric acid.

The ammoniaization of the superphosphoric acid may be pressurized or pressureless.

Technological process through superphosphoric acid is less suitable, especially because of its high cost, because of the difficulties associated with the corrosion of the device in its preparation (concentration) and in its neutralization with ammonia, but the main cause is the underutilization of neutralizing heat.

This is because the ammoniaization of superphosphoric acid releases about 250,000 kcal per tonne of polycondensated phosphates, and if this heat is also used, for example

199 819 for the evaporation of liquid ammonia, there is still a surplus of about 180 000 koa / t of melt of polycondensated ammonium phosphates of composition 15-60-0, so that most of the heat must be removed by cooling.

With regard to the economy of production, before 1960, it was seriously considered that the development of technologies should focus not on "superphosphoric acid, but on commercial phosphoric acid." This view arises as a logical consequence of economic considerations that it is preferable to utilize the neutralizing heat released during the reaction of ammonia with phosphoric acid to evaporate free and molecular water from the reacting acid rather than using an external heat source alone to prepare polycondensated phosphoric acids. neutralize with ammonia to form a melt of polycondensated ammonium phosphates, the released neutralizing heat being removed by cooling. This so-called. a direct method of preparing melt of polycondensated ammonium phosphates by neutralizing orthophosphoric acid with ammonia gas using neutralizing heat has two main advantages:

1. The neutralization heat released by the reaction of orthophosphoric acid and ammonia is fully recovered directly in the production process.

2. simultaneous neutralization reduces the corrosivity of the environment, which is otherwise a serious problem in the orthophosphoric acid thickening and polycondensation.

The direct method of melt production of ammonium polyphosphates is protected by a number of patents which differ from each other in at least the kind of acid used, its purity and concentration, the way of ammonia, the type of reactor used, the way of excess ammonia capture, temperature reactants, and the foaming of ammonia.

In recent years, a series of jobs related to the direct o

preparation of polycondensated ammonium phosphates.

The major difficulty in the direct production of polycondensated ammonium phosphate melt for the production of liquid multicomponent fertilizers from commercial extraction acids is mainly due to the foaming of the acid in the first stage of ammoniaization (in the abserber), which is caused by the presence of organic substances in the acid.

Other difficulties associated with considerable corrosion of the production equipment (T-reactor, separator, absorber), the formation of non-resorbable compounds, respectively. of non-absorbable PgO2, which is associated with a higher content of RgO3 ^{in the} treated phosphoric acid, yet with the failure to achieve the necessary conversion of orthophosphates to polycondensated phosphates, with insufficient use of ammonia and the like.

By switching from batch to continuous ammoniacalization (most of the known methods are two-stage and multi-stage ammoniacalization) and mainly by using tubular reactors instead of conventional stirrer-equipped boiler reactors, much of these difficulties have been eliminated. In multi-stage ammoniaization, however, it is necessary that the predominant part of the fresh and partially already neutralized ammonia phosphoric acid is circulated at temperatures above 100 ° C (usually 120 to 160 ° C), which however creates favorable conditions for considerable foaming at this stage.

Another serious and technology only very difficult to manage production problems

199 819 melt, resp. of a basic solution of polycondensated ammonium phosphates from extracting orthophosphoric acids; The "black" type of continually guided ammoniaization in today's reactors is the formation of patches on the walls of the process equipment. The layer of incrustation, the formation of which is conditioned by the content of impurities of inorganic and organic character in the treated acid, worsens heat transfer.

It has now been found that most of the aforementioned drawbacks of the melt production methods of polycondensated ammonium phosphates used, such as e.g. foaming occurring during neutralization of especially phosphoric acid extraction with ammonia gas, formation of patches on the walls of process equipment, insufficient conversion of orthophosphates to polycondensated phosphates etc. can be removed by neutralization or even dehydration (of free and molecular water) after atomization of phosphoric acid , or a liquid consisting of a solution or suspension of ammonium phosphates in phosphoric acid, or by spraying a concentrated solution, suspension or melt of ammonium phosphates to form fine drops of 1 · 10 ”^ to 1.5 · 10 ~ ¹ cm in a heated or unheated ammoniacal environment.

The mean particle size of the sprayed non-Newtonian or Newtonian liquid is determined primarily by the choice of spraying equipment, the basic spraying technological conditions / e.g. choice of revolutions and diameter of sprayer sprayer holes - reep atomizer. spray pressure using spray nozzles and similar / as well as physicochemical properties of the spray liquid.

Particularly fine atomization of the liquid, ´, can be achieved by using two-nozzle nozzles. It has also been found that excess-unreacted ammonia from the atomization spreader can advantageously be adsorbed to a weakly aqueous solution of polycondensated ammonium phosphates and / or water, and the resulting aqueous ammonia solution can advantageously be used to melt the melt of the polyphosphate .

The aforesaid ammonia sorption method is also advantageous with respect to the entrapment of fine aerosol of the spray liquid.

Liquids in the form of fine droplets can be atomized in a relatively sealed preator by means of a disk atomizer or by means of a single or two-component nozzle, preferably a two-component nozzle with internal or external mixing, preferably and external mixing.

. By means of a relatively melt polycondensated ammonium phosphate, the enclosed space may be unheated or heated either by combustion gases or by indirectly heated air and / or superheated steam.

Spraying liquids into fine droplets in a heated, relatively enclosed space and can be made co-current or countercurrent with respect to the flow of the heating medium.

The excess ammonia required to achieve a sufficient degree of ammonia is trapped by abaorbing in water and / or in a circulating weak acid aqueous solution of polycondensated ammonium phosphates. The ammonia obtained by absorption can be water

199 819 preferably used for the preparation of the final product - a concentrated liquid multi-component fertilizer, for example of the type 10-34-0.

The heat released by the melt feeding of the polycondensated ammonium phosphates into the ammonia water can advantageously be used for the evaporation of liquid ammonia and optionally for preheating the metered phosphoric acid.

Advantageously, variously modified spray or jet / fluid / driers can be used in the process of the invention. Spraying the liquid component of the reaction system / phosphoric acid, a solution or suspension of ammonium phosphates in phosphoric acid, a concentrated solution or suspension or a melt of ammonium phosphates into fine droplets in the above manner creates an enormously large reaction surface, thereby allowing perfect contact of the reactants.

Due to the neutralized heat brought about by the reaction, evaporation of not only free but also of molecular water is achieved, as a result of which melt of polycondensated ammonium phosphates can be obtained with high conversion of orthophosphates to polycondensated phosphates.

It has further been found that the process according to the invention can also be used to treat the extracts of the so-called black type, which contain a relatively large amount of inorganic and organic impurities, without the need for mechanical or chemical foaming or purification of the acid. liquid extraction. Furthermore, a surprising effect has been achieved in that, by suitably adjusting the dosing of the reactive components, the inlet temperature and the outlet temperature, as well as the amount of heat transfer medium, phosphoric acids of lower concentration than conventional can also be processed according to the invention for commercial extraction acids / about 52 to 54% ^P 2 ° 5

The heat of the exhaust gases, consisting of a heat transfer medium, ammonia and dehydration of the water vapor produced, can advantageously be used to preheat the feed material system, in particular to preheat the liquids to be treated.

Another advantage of the process for the production of polycondensated ammonium phosphates according to the invention is the novel method of trapping excess ammonia. According to hitherto known methods of melt production of polycondensated ammonium phosphates by two-stage ammoniacalization of phosphoric acid / method of TVA, Kaltenbach et al. The excess ammonia is bound in a preheated, dosed phosphoric acid system, which in most known technological processes circulates through the abserbs at a temperature of 135 to 155 ° C. The partially ammonia-neutralized phosphoric acid has a pH of about 1.5 to 2.0 at the outlet of the abserb, which corresponds to a degree of ammonia of about 100 to 120 g NH 4 per 1 kg of P 4 O 4 in the acid treated.

The absorption of ammonia in the hot circulating phosphoric acid is associated with considerable difficulty, both on the one hand and on the foaming of the absorbent and on the other hand on its corrosivity, which places high demands on the corrosion resistance of the circulation pump material and its construction.

According to the invention, excess ammonia is trapped by absorption in water and / or in a besieging or acidic aqueous solution (pH 4.8-6.6) of polycondensated melt

199 819 ammonium phosphate max. 60 ° C by heat. The ammonia water from the abaorbar ea uses polycondensed ammonium phosphates to dissolve the hot melt.

The disadvantage of this method of trapping excess ammonia is, on the one hand, a substantially lower corrosion of the abaorbent, i.e., a reduction in the amount of ammonia. a weakly acidic aqueous solution of polycondensated ammonium phosphates, in comparison with a corrosivity of 135-160 ° C of warm, partially neutralized ammonia phosphoric acid, and has virtually complete elimination of foaming in this process stage.

This novel method of melt production of polycondensed ammonium phosphates and its treatment on a base NP - approximate bedding solution 10-34-0 can be advantageously carried out in a continuous manner by means of a device consisting of a relative melt cap enclosed, unheated or with combustion gases and / or superheated gas. 20. provided with a spraying device 21. which may be a single or a die nozzle and internal or external. mixing, or atomizing disk-atomizer. Further, the apparatus comprises from a dissolution apparatus g, which is predominantly vaporized by the heat-treated ammonia, from a heat exchanger assembly 11, 12, 13, and a device which serves to eorbicate unreacted ammonia gas, g.

Three variations of the eu production apparatus shown in Figures 1 to 3. Figure 4 shows a bifurcated nozzle and external mixing, which can advantageously be used as a spray device 21.

One of the devices which allows the β advantage to produce a base NP solution is shown in FIG. 1

Liquid containing inorganic substances characterized by PO. a group, preferably 4 phosphoric acid, or a mixture of phosphoric acid and phosphates, or a solution, a suspension or a melt of ammonium phosphate, is metered and transported to the reservoir 6 via a metering pump via a heat exchanger 12 in which it cools the abeorbent. the ammonia water supplied from the abeorber 6 and through the heat exchanger 13, in which it is further preheated by utilizing the heat of the gas mixture discharged from the separator 31.

The pre-heated liquid is metered into the spray / atomizing / fine droplet device 21. The device may be a spray disk atomizer, a single or bifurcated nozzle, and preferably a bifurcated nozzle β by external or internal mixing, and preferably with external mixing / mixing. (Fig. 4). Liquid ammonia ea feeds a polycondensated ammonium phosphate from the reservoir 2 via a hot melt solution preparation apparatus, which also has the function of an evaporator g, where liquid ammonia is vaporized and initially preheated as a result of heat melt.

Along with the influence of evaporation heat of liquid ammonia and from the tea and also due to its specific heat, the prepared melt solution of polycondensated ammonium phosphates is cooled.

The gaseous and partially pre-heated ammonia is fed from the equalizing pressure buffer reservoir 6 to the metering spray nozzle 21 or via the distributor 22 under the spray disk-atom.

199 819

The heat transfer medium (hot combustion gases) 23 at a temperature and in an amount dependent at least on the concentration of the treated liquid containing the inorganic substances characterized by the PO4 group and the desired conversion of orthophosphates to polycondensed phosphates in the melt and in the melt .

The heterogeneous reaction system, consisting of liquid sprayed into fine droplets and ammonia gas, represents a system with an enormously large reaction surface, so that, at a suitable temperature regime, optimal conditions are created not only for evaporation of free water but also for molecular dehydration by in the reaction system of the inorganic substances present, characterized by a PO4 group, preferably ammonium phosphates. The molten polycondensated ammonium pyrophosphate formed by molecular dehydration is collected at the bottom of the relatively closed spray chamber.

Due to the considerable corrosion of the hot melt of polycondensated ammonium phosphates, the spraying space must be made, respectively. lined with corrosion by inert msterials. The resulting melt of polycondensated ammonium phosphates flows through the melt cap into a dissolving device equipped with an ammonia evaporator J where the solute in the ammonia water continuously fed from the storage tank 6 of the absorption column g is mixed with the overflow portion of the polycondensated phosphate 2 ·

The off-gases 24, consisting of a mixture of superheated steam, combustion gases and excess ammonia, are separated from the entrained melt droplets of the polycondensated ammonium phosphates in the separator-cylinder 31 and their heat (particularly condensation heat) is largely removed in the condensation heat exchanger 13. liquid.

The excess, unreacted ammonia gas is largely collected in the absorption tower 5 in water and collected as ammonia water in the reservoir 6 from where a portion of it is discharged to prepare a solution of polycondensated ammonium phosphates into a dissolution apparatus equipped with ammonia evaporator J. 6. DC continuously replenish with water.

For maximum absorption efficiency, the absorbent-dilute ammonia water is cooled in a heat exchanger JN2, which is integrated into the absorbent circulation circuit. Possible residues of unabsorbed ammonia aa are collected in a weakly acidic aqueous solution of polycondensated ammonium phosphates (pH 5.5 to 6.6) in absorption column 2, the final product-base NP-solution of approximate composition 10-34-0 / pH 6.5 to 7.0 / s and continuously discharged from container 8.

The entrapped tiny absorbent droplets, i. 10-34-0, are separated in the cyclone 33 from the exhaust gases g.

Another variant of the melt production plant of polycondensated ammonium phosphates further processed to a basic solution of the approximate composition 10-34-0 according to the invention is shown in FIG. 2. Superheated steam is used as a heat transfer medium to heat the spray chamber with a relatively closed melt cap. The liquid, containing inorganic substances characterized by PO ^-groups, is removed from the reservoir

198 919 dispenses and transports by means of a metering pump through a heat exchanger assembly 11, 12, 13, 14, in which the liquid is gradually heated up to its boiling point.

The preheated liquid is metered into the spray device 21. Liquid ammonia e is dosed from the reservoir 2 into the evaporator placed in the blower device J, where aa is gassed and occasionally preheated. The gaseous partial preheated ammonia aa is metered into a bifurcated nozzle and preferably and by external mixing or teat under a spreading coil.

For the most efficient spraying of liquid into fine droplets through a nozzle, a superheated water pen can and preferably be used.

Superheated water vapor is fed to the relay-sealed preatoreurospray 20a and via the tubular water superheater 42. The amount of water vapor supplied is preferably such that the total amount obtained from both condensation and ddration is sufficient to prepare a base NP solution of approximately 10-34-0.

Temperature to which the steam needs to be superheated. it depends on the concentration of the treated liquid (water content), the temperature of the components of the reaction system to be metered, the size of the sprayed particles obtained, the desired degree of conversion as well as the melt polycondensation, reep. solution of polyconaensated ammonium phosphates and the like.

The heat of the combustion gases discharged from the tubular superheater 42 is utilized in the after-stage preheating of the process liquid 14.

The dehydrated polycondensated ammonium pyrophosphate melt obtained is continuously discharged through a melt cap, closing the like of the spray space, to a dissolving apparatus equipped with a liquid ammonia evaporator J, where aa dissolves in the continuously supplied ammonia water from the vapors of the absorbent column. The resulting basic solution is cooled to temperatures below 60 ° C, in addition to the evaporative heat of liquid ammonia, by circulating it through the heat exchanger 11.

2o a mixture of water vapor and excess ammonia removed from the relatively enclosed preator by spraying 24a and separating the entrained melt particles of condensed ammonium phosphates in a cyclone 31 separator.

The heat of this gas, in particular the condensation heat of the water vapor and ammonia gas, is discharged in the heat exchanger 13 where it is used to preheat the liquid to be fed to the spray device,

The 2 residues of unconcentrated water vapor and ammonia are separated from the condensed ammonia water in a separator 32 and collected in an absorption column 6 in circulating ammonia water. The ammonia water from the separator 32 and the absorption column 6 is collected in a reservoir 6, from where a part of it is discharged to the start-up apparatus J to prepare a cea 10-34-0 base NF-solution. Water can be added to the reservoir 6 as needed to replenish the absorbent and optionally dilute the ammonia water to the desired concentration to prepare the base NF-solution.

199 819

The last remnants of ammonia ▼ neabeorfeovaného first absorbent ⁸⁸ Step 2 zechytévajú ▼ cirkulujúoom weak acid solution of ammonium phosphate in the polycondensed abaorbčnej column 2j wherein the resulting final product, i.e. 10-34-0 base solution with a pH of about 6.5 to 7 and continuously discharged from the reservoir 8.

The entrained small drops of absorbent a and from the gases blown by the end fan 6 separate in the cyclone separator 33.

The process for producing liquid multicomponent fertilizers via the melt of polycondensated ammonium phosphates according to the invention can be carried out on another variant of the apparatus shown in FIG. Third

This device is depicted from FIG. 2 differs only in the method of superheating of the water vapor (heat transfer medium) introduced into the relatively closed spray jet.

In FIG. 2 shows an apparatus for indirectly superheating water vapor while using combustion gases from the apparatus to heat the feed liquid in the heat exchanger 16.

The device of FIG. 3 shows the direct overheating of water vapor, which is carried out by introducing water vapor just after the burner 41 into the combustion gas stream. The mixture of combustion gases, and in this way superheated water vapor, is led to a relatively enclosed spray area 20, 23.

The lath device is similar to the device already described and shown in FIG. 2. New method of production of polycondensed ammonium phosphates for the preparation of concentrated liquid multicomponent fertilizers, resp. for the preparation of a base NP-solution of approximate composition 10-34-0 on the apparatus according to the invention by allowing, among other liquids containing inorganic substances characterized by a PO 4 group, continuous processing of less valuable black phosphoric acid extracts with a high organic content and higher content water (lower concentrated phosphoric acids) has a number of advantages.

The advantages consist in maximum efficiency in terms of heat utilization, in terms of technology control, in the possibility of achieving, at a relatively short residence time in the reaction zone, high conversions of orthophosphates to polycondensated phosphates at a relatively low degree of polycondensation / max. n = 3-4) as a result of the large reaction surface accomplished by spraying the liquid onto small droplets, thereby creating optimal conditions for rapid reaction and dehydration.

The following examples illustrate but do not limit the scope of the invention.

Example 1

An average of 60 kg of a 50% aqueous solution of technically pure ammonium orthophosphate (Amofos), which is used as a NP-fertilizer containing 12.85% N and 53 hours, was dosed on an hourly basis into a disc atomizer-atomizer sprayer heated with natural gas combustion gases. 7% of the total PgO4. P ^I 'í®® ^ei' »s and on the temperature of the feed solution was maintained in the range of 55 65 ° C EZ. The temperature of the off-gases / combustion gases, water vapor / e was maintained in the range of 230-300 ° C, and preferably 250-260 ° C. A capacity of 25 to 27 no

198 819 kg melt of polycondensate ammonium phosphates per hour of average composition of 12.5% N and 62.5% 22.5 ^{The pattern of} melt of polycondensated ammonium phosphates taken during the experiment showed 45-55% conversion of orthophosphates to polycondensated phosphates.

^P 2 ° 5 ^T0 ^ ^orme orthophosphate and polycondensed phosphates was determined by ion exchange-ehromatogrefie / ion exchange on báziekom /.

It was found by the method of qualitative paper chromatography on paper that the melted samples taken contain, in addition to orthophosphates, biphenyls and triphosphates, to a small extent also quaternary phosphates.

Example 2

Approximately 100 kg of an aqueous suspension of NP-fertilizer based on ammonium orthophosphate / Amofos containing 12.85% of N and 53.7% were dosed into a disc atomizer-atomizer of a direct-gas-fired drying kiln containing 30% by weight of Amofoeu 70 parts by weight water.

The temperature of the feed slurry ea was maintained at 60 to 70 ° C, the temperature of the outlet gases was kept at 230 to 300 ° C, preferably at 250 to 260 ° C. A capacity of 62 to 65 kg of melt of polycondensated phosphates per hour with an average composition of 12.2% N and 63.4% Ρ ₂₀ % present in the form of polycondensates was achieved, with the highest polycondensate represented in the melt being n = 5.

Example 3

In the bifurcated nozzle and external mixing (FIG. 2) 63 kg of phosphoric black type extraction acid of a concentration of 54% PgO2 / h was dosed in a spray drier. Extractive phosphoric acid was preheated to 120 to 130 ° C, at the same time 9.2 to 9.4 kg of preheated ammonia gas were dosed. The temperature in the spray nozzle was in the range of 220-245 ° C. The temperature of the off-gases aa was in the range of 230 to 300 ° C, preferably 250 to 260 ° C. It has an average capacity of 53 to 54.5 kg of a substantially foamed brown-black melt of polycondensated ammonium phosphates per hour with an average composition of 11.8% N and 62.8% P 2 O 4. ^{in the} course of the experiment samples collected melt containing more than 40% of the PGO ^ ▼ polycondensed form, the top poly condensation in a melt had a C - 4th

Example 4

2 kg of the black phosphoric acid extract with conc. 54% PgO 4 ^per hour, the acid being preheated to 120-130 ° C and 13.2-13.5 kg to 60-70 ° C pre-lit ammonia gas per hour. The temperature of the outlet gases was in the range of 230-300 ° C, preferably 250-260 ° C. The heat of the outlet gases ea utilized in a condensation heat exchanger to preheat the phosphoric acid fed to the atomizer nozzle. Ammonia water obtained by condensation of the off-gases was used as an abaorbent to capture ammonia from the gas mixture exiting the atomizer. A capacity of 54.4 kg of polycondensated ammonium phosphate melt per hour was achieved,

199 819 at 5 ° to 60 ° C dissolved in 45.6 kg of ammonia water (2 +, 7 kg of ammonia water from condensation and 23.9 kg of water added to the abaorption). In this way we obtained 100 kg of liquid NP-fertilizer with a composition of 10.7-33.9-0 with a pH of about 6.0. The crystallization temperature of the obtained liquid fertilizer was less than -14.5 ° C and its specific gravity at 20 ° C was 1400 kg.m -1.

Claims (2)

1. A process for the production of polycondensated ammonium phosphates for the preparation of concentrated multi-component liquid fertilizers by neutralizing and / or dehydrating a Newton or non-Newton liquid containing an inorganic compound and a PO2 group, characterized in that the neutralization and / or dehydration is carried out ^ 1,5.10 to ^"1 em in a heated or non-heated smoniakálnom environment, the ambient temperature is in the range of 190-420 ° C, excess ammonia is bound sorption. 2. A method according to claim 1, wherein the excess ammonia is preferably trapped in an acidic aqueous ammonium polyphosphate solution.