CS206802B1 - Manufacturing method of stable liquid np fertilizer type 8-24-0 - Google Patents

Description

( ⁵⁴ ) A method for producing stable liquid NP fertilizers of type 8-24-0.

The present invention relates to a process for the production of stable liquid NP fertilizers of type 8-24-0 from extractive trihydrophosphoric acid by discontinuous neutralization.

It is known that the neutralization of the extractive trihydrophosphoric acid with ammonia produces insoluble gel-like and crystalline precipitates, in particular Fe phosphates,

Al, Mg and Ca. These solid particles can then cause difficulties, especially during long-term storage, fertilizer transport and application,

A number of fertilizer production and treatment methods have been proposed to address this deficiency. One possible way of making the NP solution is to neutralize the acid to a pH of 7 or higher and then lower the pH to 6.7 by adding the acid to the solution. A gel-forming clay is added to improve the stability of the impurity suspension.

Another method consists in continuously settling impurities of the NP solution, thereby obtaining up to 65% PgO 2 in the clear solution. The preparation of the NP solution is carried out by ammoniacalization in two steps to obtain a well-settling solution (Potts J.M., Rindt D.W. and Slck A.V. 1962, Chem. Eng. Progr. 58 (9), 89-93).

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Another simple method is slow ammoniacalization at a higher temperature that allows the preparation of a well filterable NP solution (US Pat · 3 109 728) ·

In many cases, a gel-forming clay is used as an suspending agent, using different clays and different methods of use (US Pat. 3,160,495,

179,496).

All of the processes mentioned above mean practically the production of low-concentration au-apertive fertilizer and the drawbacks resulting from the suspension nature of the fertilizer cannot be completely eliminated by the above methods. Filtration of NP solution is technologically demanding.

Other methods of making NP solutions consist of sequestering impurities by polyphosphates (US Pat. 3,057,711; Slack AV, Potta JM and Shaffer HB, 1965, J. Agr. Food Chem. 13 (2) 165-71} Wilbanka JA, Naeon MC and Seott WC 1961 J. Agr.

Food Chem. 9 (3) 17 & -178).

It has now been shown that by suitably carried out by intermittent neutralization, an NP solution can be produced, whereby precipitation and formation of insoluble impurities in a very fine, readily re-dispensable form can occur.

SUMMARY OF THE INVENTION The present invention provides a process for the production of stable liquid NP fertilizers by deacontinuous neutralization of the trihydrophosphoric acid extract with gaseous and / or liquid ammonia and / or ammonia water, characterized in that the neutralization rate kg of NH 3, wherein the cooling mode of the reaction is realized such that the neutralization temperature to a pH of 5 to 5.5 is greater than 50 ° C, preferably 70 ° S to 80 ° C and the temperature during further neutralization to a final pH of 6 Preferably, the amount of from 1 to 7 is less than 50 ° C, and preferably 40 to 30 ° C.

The possible addition of gelling and auspension agents with this fertilizer is considerably more efficient than in the production of an NPP solution by various variants in a continuous manner.

Preconditions for the formation of fine particles in the neutralization of NP solution are the rate of change of ammonia concentration and temperature mode of neutralization of the solution, while the limitations of the rate of change of concentration do not limit the production capacity.

Compliance with these temperatures does not cause any problems. Due to the limited rate of acid neutralization, it is possible to dissipate the heat of reaction of this exothermic reaction in a neutralizer of various types with little heat dissipation. Even the need for reducing the rate of ammonia for low rate of ammonia for low rate of cooling is not a defect, as follows from the present invention. These temperatures are achieved by changing (limiting) the flow of cooling water (or other cooling medium or cooling method).

The agrochemically active component in liquid NP fertilizer 8-24-0 is a mixture of mono and dihydrophosphates, which are completely dissolved in the fertilizer. The method of producing NP fertilizers according to the invention does not affect the agrochemical activity of ammonium phosphates in any way; a possible increase in agrochemical activity compared to solid fertilizers of similar composition, eg Amofos, results from the liquid form of fertilizer.

The NP solutions produced according to the invention form a solid particle deposit very fine and well-miscible, which does not cause storage or handling difficulties. The following examples describe, but are not limited to, the invention.

Example 1

432 g of Norwegian extraction phosphoric acid having a P ₂ O 50 50% content was diluted with 468 g of water and neutralized with ammonia gas, while the temperature of the solution reached 70 ° C during neutralization and was maintained at this value until pH 5.3. Thereafter, cooling was increased so that the temperature dropped to 30 ° C and this temperature was maintained until the pH reached 6.8. The neutralization lasted 56 minutes. The solution was then cooled to 20 ° C and stored. During storage, insoluble impurities settled and formed, but due to their delicate character they were very easily resuependable and settled slowly.

NP solution has these properties i

N content 7,46%

Content Ρ £ θ5 tot. 23,62% density 1 292 kg m “(at 20 viscosity 7 m P a.s (at 20

1,108 g of NP solution were obtained. The rate of ammonia was 115 kg NH-/ t h ° C

° C)

Example 2

502 g of Tunisian extraction phosphoric acid having a PgO content of 3% were diluted with 498 g of water and neutralized under the same conditions as in Example 1. The neutralization lasted 54 minutes. The resulting fine particles were very easily re-suspendable after 5 days of storage.

The NP solution had these Properties: Contents N čp 7.57% Content? 2θ5 tot. 23,88% density 1 296 kg m ³ (at viscosity 8 m P a, a (at It was obtained 1 108 g of NP solution

The rate of ammonia was 120 kg NH 2 / t h

Example 3

The Norwegian extraction acid diluted with water to a PgO content of 26.6% was neutralized in a 62 L reactor with ammonia gas. Ammonia was carried out for 1.5 hours at a uniform rate up to a pH of 6.9. The temperature rose to 80 ° C during the neutralization and was maintained at this value until a pH of 5.3 was reached. Thereafter, cooling was intensified and the temperature was maintained at 40 ° C until neutralization was complete. The fertilizer was cooled to 20 ° C and stored for 10 days in a 50 L polyethylene canister. After this time, the canister was poured out slowly by inverting. Only a small amount of sludge remained at the bottom, forming a discontinuous layer, less than 0.5 mm thick.

The NP solution had the following properties:

N content 7.32%

Contents P ₂ O ₅ oel. 23.41% density 1 287 kg m ³ (at 20 ° C) viscosity 8 m P as (at 20 ° C) 80 kg NP solution was obtained Ammonia rate was 65 kg NH 4 / th

Claims (1)

Object of the invention Method for producing a stable liquid NP fertilizer of the type 8-24-0 by intermittent neutralization of the trihydrophosphoric acid extraction acid with gaseous and / or liquid ammonia and / or ammonia water, characterized in that the rate of neutralization, expressed as ammonia per 1 tonne over 200 kg of ammonia, wherein the cooling mode of the reaction is such that the neutralization temperature to a pH of 5 to 5.5 is above 50 ° C, preferably 70 ° C to 80 ° C and the temperature during further neutralization to a final pH 6 to 7 is less than 50 ° C, preferably 40 ° C to 30 ° C.