RU2344113C1 - Method of calciumazotosulphate fertiliser production - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention refers to production method of complex fertiliser containing nitrogen, calcium and sulphur, and application thereof in chemical industry. Substance of method consists in preparation of aqueous pulp of humidity 5÷15 wt %, containing ammonia nitrate and sulphate and calcium salts, and granulation thereof in granulating drum. Granulation includes pulp mixed ammonium nitrate solution and ammonium sulphate in mass ratio NH₄NO₃:(NH₄)₂SO₄, equal to (2.7÷4.8):1. Prepared mixed pulp is steamed and added with calciumcarbonate-containing reagent in mass ratio CaCO₃:(NH₄)₂SO₄ equal to (0.6÷0.9):1.

EFFECT: production of fertiliser meeting current requirements of particle-size distribution with base grain size 2÷5 mm.

4 cl, 1 ex

Description

The invention relates to a method for producing a complex fertilizer containing nitrogen, calcium and sulfur, and may find application in the chemical industry.

In agriculture, complex fertilizers based on ammonium nitrate, additionally containing calcium or sulfur compounds, or both components at the same time, are increasingly used.

A known method of producing complex fertilizers containing nitrogen, calcium and sulfur, comprising mixing the melt of ammonium nitrate with a component or components containing calcium and sulfur, and granulating the resulting mixture. Moreover, as components containing calcium and sulfur, limestone, chalk, dolomite, cement dust, metallurgical slag, phosphogypsum and / or mixtures thereof are used. Ammonium nitrate melt is fed to the mixing stage in an amount of 1 ÷ 70 wt.% Of the total mass, and the remaining amount of melt is sent to the granulation stage [ed. USSR No. 1505920, MKI 4 C05C 1/00, publ. 09/07/89, bull. No. 33]. The disadvantage of this method is the complexity of its implementation in an industrial environment.

Closest to the present in technical essence and the achieved result is a method of producing calcium-azotosulfate fertilizer [US Pat. RF №2186751, IPC 7 С05С 1/00, C05G 1/00, C05G 1/08, publ. 08/10/2002, bull. No. 22], including the preparation of aqueous pulp with a moisture content of at least 5%, containing ammonium nitrate and salts of sulfate and calcium, followed by its granulation in a drum granulator dryer. Ammonium nitrate melt is taken in an amount of 60 ÷ 98% by weight of the fertilizer. As a calcium-containing component, gypsum, phosphogypsum, metallurgical slag and / or mixtures thereof are used. As a calcium-containing component, dolomite, chalk, limestone, cement dust and / or mixtures thereof are used. Sulfur, potassium sulfate, magnesium sulfate and / or mixtures thereof are used as a sulfur-containing component. When this receive fertilizer containing, wt.%:

N 20.40 ÷ 33.2 Sa 0.59 ÷ 11.76 S 0.47 ÷ 9.41.

The disadvantage of this method is the low consumer properties of the obtained fertilizer due to the mismatch of the particle size distribution to the modern requirements of consumers: the main fraction of the granules of the obtained fertilizer has a size of 1 ÷ 4 mm, while in accordance with the requirements of consumers presented to fertilizers containing nitrogen, calcium and sulfur, the main fraction of the granules should have a size of 2 ÷ 5 mm

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

The stated technical problem is achieved by the fact that in the method for producing calcium-azotosulfate fertilizer, which includes preparing aqueous pulp with a moisture content of 5-15 wt.%, Containing ammonium nitrate and salts of sulfate and calcium, granulating the latter in a drum granulator dryer, according to the invention, the pulp prepared by mixing the NH ₄ NO ₃ ammonium nitrate with ammonium sulphate solution in a weight ratio of: (NH _{4) 2} SO _4, equal to (2,7 ÷ 4,8): 1, its evaporation and adding to the pulp kaltsiykarbonatsoderzhaschego ReA cient in a weight ratio of CaCO _3: (NH _{4) 2} SO _4, equal to (0,6 ÷ 0,9): 1.

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.%.

Synthetic chalk, a by-product of the production of complex fertilizers obtained by the nitric acid technology, is used as a calcium carbonate-containing reagent.

Example

In a 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 (2 , 7 ÷ 4.8): 1, adjusting the pH of the mixture within 4 ÷ 6 by the introduction of ammonia or ammonia water, and evaporate to a residual moisture content of 12 ÷ 16%.

One stripped off pulp in an amount of 24 ÷ 26 t / h is sent to the mixer reactor, 3.1–4.6 t / h of synthetic chalk, a by-product of the production of complex mineral fertilizers containing 93% calcium carbonate, is added thereto, maintaining the mass ratio in the pulp CaCO ₃ : (NH ₄ ) ₂ SO ₄ equal to (0.6 ÷ 0.9): 1.

The resulting pulp with a moisture content of 5 ÷ 15% is granulated and dried in a drum granulator-dryer (BGS) with a diameter of 4.5 m, length 16 m, maintaining the temperature of the flue gases at the inlet of the BGS 160 ÷ 200 ° C.

Get the target product - calcium-nitrogen-sulfate fertilizer containing 92 ÷ 95% of the granule fraction with a size of 2 ÷ 5 mm and having the following chemical composition, wt.%:

N 26 ÷ 28 CaCO ₃ in terms of CaO 6 ÷ 9 S 4 ÷ 5

From the presented data it follows that, in accordance with the present invention, the method stably provides fertilizer, the main fraction of which has a granule size of 2 ÷ 5 mm, satisfying the requirements of consumers, that is, it can improve 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. If you go beyond the declared limits, the stability of the particle size distribution is violated.

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

As a calcium carbonate-containing reagent, the most technologically advanced is synthetic chalk, a by-product of the production of complex fertilizers obtained using nitric acid technology. In addition to synthetic chalk, it is possible to use finely ground limestone or dolomite.

Claims (4)

1. The method of producing calcium-nitrogen-sulfate fertilizer, including the preparation of aqueous pulp with a moisture content of 5-15 wt.%, Containing ammonium nitrate and salts of sulfate and calcium, granulating the latter in a drum granulator-dryer, characterized in that the granulation is subjected to pulp prepared by mixing a nitrate solution ammonium with ammonium sulfate in a mass ratio of NH ₄ NO ₃ : (NH ₄ ) ₂ SO ₄ equal to (2.7 ÷ 4.8): 1, evaporating it and adding a calcium carbonate-containing reagent to the pulp in a mass ratio of CaCO ₃ : (NH ₄ ) ₂ SO ₄ equal to (0.6 ÷ 0 , 9): 1. 2. The method according to claim 1, characterized in that the concentration of the solution of ammonium nitrate during mixing is maintained within 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 as a calcium carbonate-containing reagent, synthetic chalk is used, a by-product of the production of complex mineral fertilizers obtained by nitric acid technology.