RU2344112C1 - Method of azotosulphate fertiliser production - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention refers to production method of fertiliser containing nitrogen and sulphate sulphur, based on ammonium nitrate and sulphate and can be used in chemical industry for production of double fertiliser type NS. Substance of method consists in preparation of aqueous pulp of humidity 7÷15 wt % and temperature above 80°C, containing ammonia nitrate and ammonium sulphate, with added reagent regulating pulp pH, and granulation in granulating drying drum. Granulated is pulp prepared by mixture of ammonium nitrate and ammonium sulphate solution in mass ratio NF₄NO₃:(NH₄)₂SO₄ equal to (2÷7):1, thereafter steamed at final temperature 142÷155°C. Reagent regulating pulp pH is phosphate additive in amount 5÷20 kg P₂O₅ per 1 t of fertiliser.

EFFECT: production of fertiliser with base grain particle size 2÷5 mm and with high granule strength.

4 cl, 1 ex

Description

The invention relates to methods for producing a fertilizer containing nitrogen and sulfate sulfur, based on ammonium nitrate and sulfate, and can be used in the chemical industry for the production of double fertilizer type NS.

In agriculture, complex fertilizers based on ammonium nitrate, additionally containing sulfur compounds, are increasingly used.

The increased interest of agrochemists in sulfur, as an element of plant nutrition, is determined by a number of reasons: a decrease in its content in the soil, an increase in the production and consumption of free or low sulfur fertilizers, and an increase in its removal from the soil due to the systematic increase in crop yields.

A known method of producing fertilizer containing nitrogen and sulfate sulfur by neutralizing nitric acid with the addition of sulfuric acid with ammonia, evaporating the neutralized solution, followed by granulation of the target product [Production of ammonium nitrate in units of large unit capacity. Ed. V.M. Olevsky, 2nd edition. Chemistry, 1990, p.130-162]. The disadvantage of this method is to obtain a product with a low content of sulfate sulfur: 0.1 ÷ 0.15 wt.% Or 0.4 ÷ 0.6 wt.% In terms of ammonium sulfate.

The closest set of essential features and the achieved result to the present invention is a method for producing nitrogen-sulfate fertilizer, comprising preparing a water pulp with a moisture content of 7 ÷ 15 wt.% And a temperature of 80 ÷ 100 ° C, preferably 91 ÷ 100 ° C, containing ammonium nitrate and sulfate ammonia, with the introduction of a reagent that regulates the pH of the pulp, followed by granulation in a drum granulator dryer [US Pat. RF №2227792, IPC 7 С05С 1/00, C05G 1/00, publ. 04/27/2004, bull. No. 12].

The disadvantage of this method is the low consumer properties of the resulting fertilizer due to the mismatch of the particle size distribution to modern requirements of consumers and the low strength of the granules.

According to our tests, the main fraction of fertilizer obtained by a known method has a granule size of 1 ÷ 4 mm, and the strength of the granules does not exceed 60 kg / cm ² .

In accordance with the requirements of consumers for fertilizers containing nitrogen and sulfur, the main fraction should have a size of 2 ÷ 5 mm. The strength of the granules at the level of 60 kg / cm ² is insufficient for fertilizers obtained by granulation in a drum granulator dryer.

The technical task of the present invention is to obtain fertilizer that meets modern requirements for particle size distribution and with higher strength granules, that is, improving the consumer properties of the fertilizer.

This goal is achieved by the fact that in the method of producing nitrogen-sulfate fertilizer, including the preparation of aqueous pulp with a moisture content of 7 ÷ 15 wt.% And a temperature above 80 ° C, containing ammonium nitrate and ammonium sulfate, with the introduction of a reagent that regulates the pH of the pulp, and subsequent granulation in a drum granulator dryer, according to the invention, the pulp is subjected to granulation, prepared by mixing a solution of ammonium nitrate and ammonium sulfate in a mass ratio of NH ₄ NO ₃ : (NH ₄ ) ₂ SO ₄ equal to (2 ÷ 7): 1, its evaporation at the final a temperature of 142 ÷ 155 ° C, and as a reagent that regulates the pH of the pulp, a phosphate additive is used in an amount of 5 ÷ 20 kg of P ₂ O ₅ per 1 ton of fertilizer.

The concentration of the solution of ammonium nitrate during mixing is maintained within 35 ÷ 90 wt.%.

Ammonium sulfate is used in the form of a solution with a concentration of 40 ÷ 45 wt.%.

As a phosphate additive, the product of the nitric acid decomposition of apatite is used.

Example

In the cascade of reactors, a 35 ÷ 90% (hereinafter% by weight) solution of ammonium nitrate and crystalline ammonium sulfate or its 40 ÷ 45% solution are mixed in a mass ratio of NH ₄ NO ₃ : (NH ₄ ) ₂ SO ₄ equal to (2 ÷ 7): 1, the mixture is evaporated in an evaporator battery, maintaining the final temperature of one stripped off pulp within 142 ÷ 155 ° С.

In order to avoid “acidification” of the pulp during the evaporation process, that is, to regulate the pH of the evaporated pulp within specified limits (pH of at least 4), a nitric acid extract neutralized by ammonia from decomposition of apatite by nitric acid with partial release of calcium nitrate by 40 ÷ 75 is introduced into the mixture before evaporation % in the amount of 5 ÷ 20 kg P ₂ About ₅ per 1 ton of fertilizer.

Salts of phosphoric acid, formed during the neutralization of nitric acid extract, play the role of a pH stabilizer that prevents acidification of the pulp.

One stripped off pulp with a flow rate of 28 ÷ 30 t / h is granulated in a drum granulator-dryer (BGS) with a diameter of 4.5 m and a length of 16 m, maintaining the temperature of the heating gases at the inlet of the BGS within 160 ÷ 210 ° C.

Get the target product - nitrogen sulfate fertilizer in an amount of 24 ÷ 26 t / h, containing 91 ÷ 96% of the granule fraction with a size of 2 ÷ 5 mm and having the following composition,%:

N _total 31 ÷ 33 S 3 ÷ 7 P ₂ O ₅ 0.5 ÷ 2.0 H ₂ O no more than 0.5.

The strength of the granules is 70 ÷ 75 kg / cm ² .

Thus, the method in accordance with the present invention provides the production of NS-fertilizer, the main fraction of the granules of which has a size of 2 ÷ 5 mm in accordance with the requirements of consumers, while the strength of the granules is higher by 20 rel. compared to the prototype. That is, the present method improves the consumer properties of the fertilizer.

The stated technical problem is solved subject to the distinguishing features stated in the first paragraph of the formula. When going beyond the stated limits, the fraction fraction of granules with a size of 2 ÷ 5 mm decreases and the strength of the granules decreases.

The concentration ranges of solutions of ammonium nitrate and sulfate are due to technological feasibility.

The use of nitric acid decomposition products of apatite as a phosphate additive is technologically feasible for plants that incorporate the production of complex mineral fertilizers obtained by the nitrogen-acid technology. In addition, phosphoric acid and ammophos can be used as a phosphate additive.

Claims (4)

1. A method of producing nitrogen-sulfate fertilizer, including the preparation of aqueous pulp with a moisture content of 7 ÷ 15 wt.% And a temperature above 80 ° C, containing ammonium nitrate and ammonium sulfate, with the introduction of a reagent that regulates the pH of the pulp, and subsequent granulation in a drum granulator dryer, characterized in that the pulp is subjected to granulation, prepared by mixing a solution of ammonium nitrate with ammonium sulfate in a mass ratio of NH ₄ NO ₃ : (NH ₄ ) ₂ SO ₄ equal to (2 ÷ 7): 1, its evaporation at a final temperature of 142 ÷ 155 ° C, and as a reagent The pH regulating pulp is applied with a phosphate additive in an amount of 5–20 kg P ₂ O ₅ per 1 ton of fertilizer. 2. The method according to claim 1, characterized in that the concentration of the solution of ammonium nitrate during mixing is maintained within the range of 35-90 wt.%. 3. The method according to claim 1, characterized in that the ammonium sulfate is used in the form of a solution with a concentration in the range of 40-45 wt.%. 4. The method according to claim 1, characterized in that the product of the nitric acid decomposition of apatite is used as a phosphate additive.