CS233406B1 - A method for preparing stabilized nitrogen phosphorus liquid fertilizer - Google Patents

Abstract

The invention relates to the preparation of a stabilized nitrogen-phosphate fertilizer containing condensed ammonium phosphates by dissolving a hot melt of condensed ammonium phosphates in water. At the same time, the weakly acidic aqueous solution is neutralized with gaseous ammonia. The melting melt of condensed ammonium phosphates has a temperature of at least 170 °C and the fertilizer is prepared at a temperature of 30 to 115 C, pH 4.0 to 8.0 in the presence of an atabilizing additive based on a bentonite suspension in sodium forae. The stabilizing additive also contains lignosulfonic acid and/or its derivatives

Description

233406 2

BACKGROUND OF THE INVENTION The present invention relates to a process for the preparation of stabilized nitrogen-phosphorus liquid fertilizer comprising ammonium condensed phosphate. In the production of liquid phosphate fertilizers and commercial crude trihydrogenphosphoric acids, there is a gradual precipitation of solid Sulfur, which is caused by impurities that are rendered acidic. By the procedure of sedimentation to sedimentation, it externally exhibits an elevated sludge concentrate, mainly near the bottom of the storage and transport containers. The sediment has problems with the handling and application of liquid manure, and since it contains nutrients, it is economically desirable for its use.

The problem of sludge precipitation and sedimentation is also known from the preparation of liquid fertilizers tsv. of the plant type, prepared with the commercial dusty phosphoric acid containing phosphorus bound in the form of monophosphoric acid (NP fertilizer 7-21-0, 8-24-0, PK fertilizer 0-20-24, etc.).

Condensed phosphorous salts, which are the basis of liquid fertilizer production 10-34-0, 11-37-0,12-40-0, 0-27-31, have the ability to bind vaSSin sludge-forming with phosphoric acid-water-soluble composites (sequestered condensed phosphorous salts) These fertilizers have a reduced tendency to form taiko resuspended sludge, but the content of the sludge is dependent on the content of condensed phosphates in the molten or slurry. in aqueous solution.

For the production of concentrated liquid fertilizers, it is often necessary to use raw materials with a high content of sludge-forming agents than the sequeetrasive ability of condensed phosphates present in the fertilizer being prepared. Thereafter, the sludge-forming precipitates and sediments. In order to prevent sedimentation, it is necessary to stabilize such fertilizers.

The stabilized aqueous solutions containing condensed phosphates can be used as liquid dispersing agents for the preparation of stabilized multi-component suspensions, which in addition to plant nutrients can contain biogenic elements, biologically active substances, pesticides, etc. The preparation of such suspension fertilizers is simple and can be realized by a simple honogenization directly in the conditions of the Agricultural Roasters.

Based on these advantages of the liquid fertilizers containing the stabilizing additive, a method of preparing a base of an ammonium nitrate-based urea suspension and urea, characterized by the insertion of 31-0-0 (New Development in Technology - 12th Demonstratlon, Oetober id — 19, 1978 - NFDC, TVA Muacle Shoals, Alabama - Bulletin Y-136, pp. 74-79). The basic nitrogen suspension contains 2% w / w of attapulgite. Attagulgite is added in the form of an aqueous dispersion containing 25% by weight of attapulgine and 0.55% by weight of TSPP (tetrasodium pyrophosphate - Na2 PgO2) to provide satisfactory rheological properties.

According to the literature data, the basic nitrogen suspension 31-0-0 allows the preparation of a suspension of multi-component manure by a simple homogenization of the 31-0-0 product with an appropriately ground solid insert (ammonium phosphate, phosphate, potassium salt, limestone, dolomite, sulfur) by adding additive additives and possibly it is also used as a dispersing agent for application formulations also containing seeds of agricultural crops.

Given that the attapulgite deposits are limited in the world, there is a need for the use of Salts minerals to stabilize the suspension, e.g. sepiolite, bentonites. From the viewpoint of the most general properties, bentonites are recognized which, when in contact with water-swelling (sodium bentonites) and bentonites, which in the water itself do not inflate, respectively. very little. 3 233406

Into the group of bentonites, the occurrence of which is more widespread (also in the CSSR) was predominantly calcareous bentonite. In order to achieve swelling, their reaction to the reaction with NagCO4-natrification is required. The disadvantage of the bentonites thus treated is the fact that they acquire consistency of the gel pastes which are difficult to handle. By reducing the concentration of bentonite in the water, the viscosity, the nature of the gel and the stabilizing agent of the agent are reduced.

It has been found that the above drawbacks can be avoided by the preparation of stabilized nitrogen-phosphorous liquid fertilizer containing condensed ammonium phosphates by dissolving the hot melt of condensed ammonium phosphates in water while neutralizing the resulting or acidic solution with ammonia gas using a stabilizer. additive according to the invention.

SUMMARY OF THE INVENTION The dissolution of a melt of condensed phosphoric ammonium having a temperature of at least 170 DEG C. is carried out in the presence of an aqueous suspendant of bentonite in sodium form at a temperature of 30 DEG to 115 DEG C. and 4.0 DEG to 8.0 DEG. The stabilizing additive also contains lignosulfonic acid and / or some derivative, most often calcium, sodium or ammonium salt.

In view of the physico-chemical and rheological properties of the liquid fertilizer to be prepared, it is preferred to maintain a temperature of 55 to 75 ° C and a pH of 5.3 to 6.8 during preparation.

It has been confirmed experimentally that the aqueous suspension suspension stabilizing agent bentonite in sodium form is advantageously prepared according to Ss. The additive thus prepared contains 6 to 18% by weight, preferably 14 to 16% by weight of bentonite solids, has a high stabilizing efficiency, good flow properties and contains about 0.2 to 5.0% by weight of bentonite. , preferably 1.0 to 3.0% by weight of lignosulfonic acid and / or a derivative thereof.

A major advantage of the process of the present invention is that a high-quality product is obtained even at relatively high levels of contaminating sludge-forming impurities in the condensed ammonium phosphate and / or phosphate. in the used phosphoric acid. A further advantage is that the liquid NP fertilizer prepared by the method of the invention allows the preparation of injection suspensions by simple mixing without the need for additional addition of stabilizing agents, and can be carried out in a continuous production process, which is particularly advantageous in high-throughput processes. The examples below illustrate, but are not limited to, the present invention. Přikladl

During the continuous preparation of nitrogen-phosphorous liquid fertilizer containing condensed phosphates of the 10-34-0 type, from the commercial extraction trihydrogenphosphoric acid, e.g. black type, containing: 54.91% total ^ 2 ^ 5 66.27 · * P2 ° 5 2 conversion of total.

0.71% Fe2O3 0.73% Α1-Οί 0.22 HgO 0.09% CaO 0.46% P was tested for the strength of the method of the invention. During one of the experiments (152 / C), a hot melt of condensed 233406 ammonium phosphates was fed to the slurry reactor into which a continuous melt of condensed 233406 ammonium phosphates flowed from the neutralization-dehydration reactor operating with the liquid phase layer. In the AALSi two experiments (153 / A, 153 / B), the amount of process water was reduced by the amount of simultaneously dosed dosed withdrawal additive on the aqueous bentonlt suspension in sodium form. Stabilization Adltl was prepared by the method of MS. AO 216 641 by gradual effective homogenisation:

80.16% by weight, water technical temperature 60-85 ° C 16.64% by weight, bentonlite powder with dollna-JelS locomotive stream containing 89.16% suSine 2.25% thickened sulfltic liquor containing 44.5% by weight a0 75% by weight of technical calcined sodium carbonate.

The dynamic viscosity of the prepared stabilizing additive and the content of 15% by weight of bentonltin resin at 25 ° C was 0.653 5 Pa.s (653.5 cP). following table.

Experimental design 152 / C 153 / A, 53 / B Type of liquid fertilizer to be prepared unstabilized stabilized Processed concentration H 2 PO 3 (56 µl) - photometer 55.56 56.85 57.27 - alkalletretr 57.35 57.58 58, 21 Average feed rate of raw materials .ΙΟ "? [Kg.e-1j - H3P ° 4 23.16 23.68 22.56 - nh3 (g) 4.91 4.45 2.96 - water 10.0 5.0 5. ° - and additives - 6.94 7.57 Average temperatures [° c] - H3PO4 before entering the reactor 125.7 131.5 127.5 - neutral-dehydration reactor 243.7 240.0 244 , 0 - NP-drip fertilizer 65,7 71,5 71,0 liquid NP-fertilizer chemical composition * - nitrogen content (* N) 10,43 10,26 10,36 - total phosphorus content (% P2 ° 5 ^ 34,22 34,48 34,57 - phosphorus content in ortho-form (% Ρ20 ^) 21,0 19,47 - degree of conversion a [%] - 39,1 # 3,7 - bentonlte content [8 suSJ ] 0 2,60 2,98 - content of sulphite extract thickened - (lignosulfonic acid calcium salt) 0 0,17 0,20 p25 density [kg.m "3j 1 389,6 1 360,4 1 374, 6 pH 1 6.3 - 6.33 Viscosity, dynamic n25 ° C, 1'L LPa «eJ 0,54 1,105 1,821 Volatility after 5 days [% w / w] 3,2 1,4 1,19

AND

Claims (2)

1. A process for the preparation of an ammonium phosphate fertilizer containing condensed ammonium phosphates by dissolving a melt of condensed ammonium phosphates at a temperature of at least 170 ° C in water with simultaneous neutralization of the effluent weakly acidic aqueous solution with ammonia. the presence of a stabilizing additive based on an aqueous suspension of bentonite in its sodium form at a temperature of 30 to 115 ° C and a pH of 4.0 to 8. 2. The process of claim 1 wherein the melt dissolves at a temperature of 55-75 [deg.] C. and a pH of 5.3-6.8.