RU2121990C1 - Method of preparing compounded granular phosphorus containing fertilizers - Google Patents

Abstract

FIELD: agriculture. SUBSTANCE: claimed method comprises mixing phosphorus-containing component with nitrogen-containing additive and subsequently granulating mixture at elevated temperature. Phosphorus-containing component is mixed with nitrogen- containing component solution to attain N: P₂O₅: H₂O ratio of 1:(0.04-0.7):(0.1-8.9) at 70-105 C, and the resulting suspension is granulated. It is desirable to use ammonium and/or calcium phosphates, phosphites as phosphorus-containing component, and to use ammonium nitrate and/or sulfate, and carbamide as nitrogen- containing component. During mixing operation, potassium-containing additive is also added. Suspension is granulated at 60-90 C. The claimed method makes it possible to produce wide range of fertilizers with high yield of commercial fraction up to 70-85%. EFFECT: improved properties of the fertilizers. 4 cl, 5 ex

Description

 The invention relates to a method for producing phosphorus-containing complex mixed fertilizers widely used in agriculture.

A known method for producing phosphorus-containing fertilizers, comprising mixing phosphate raw materials with sulfuric acid and dry ammonium sulfate and subsequent heat treatment of the resulting mixture. According to this method, phosphite is mixed with sulfuric acid and dry ammonium sulfate at their ratio in a mixture of P ₂ O ₅ : H ₂ SO ₄ : (NH ₄ ) ₂ SO ₄ = 1: (1.4 - 3.1): (1 - 2.8). The mixture is further calcined at a temperature of 350-500 ^o C. (Technology of phosphorus-containing complex fertilizers. "Chemistry", 1987, S. 304)
The disadvantage of this method is primarily the receipt of fertilizer not in granular form, increased energy intensity, the complexity of the technological design, as well as the inability to obtain a wide range of fertilizers.

Closest to the described technical essence and the achieved result is another known method for producing granular phosphorus-containing complex mixed fertilizers, including mixing the phosphorus-containing component with a nitrogen-containing additive and subsequent granulation of the mixture. According to this method, phosphorite is used as a phosphorus-containing component, which is mixed with sulfuric acid and a dry nitrogen-containing component (ammonium sulfate), the mixture is fed to granulation, where an additional solution of ammonium sulfate is introduced and granulation is carried out at a temperature of 70-140 ^o C. The ratio of the mixture of components (before the granulation step) N: P ₂ O ₅ = 1: (0.043 - 8.39). (Pat. RF N 2084432, C 05 G 1/06, 07.20.97)
However, in this method, only ammonium sulfate can be used as the nitrogen-containing component, since with dry mixing of the phosphorus-containing component, other nitrogen-containing additives and especially urea lead to increased hygroscopicity of the mixture and its sticking into large pieces, which significantly worsens the conditions of subsequent granulation and reduces yield of product fraction of the product (granules 1-4 mm). So the yield of product fraction of the product does not exceed 60%.

 In addition, the proposed method does not allow to obtain a wide range of fertilizers in one technological scheme.

 We set the task of obtaining fertilizers of a wide assortment with a sufficiently high yield of the product fraction of the product.

The problem is solved in a method for producing granular phosphorus-containing complex-mixed fertilizers, including mixing a phosphorus-containing component with nitrogen-containing and other additives and subsequent granulation of the mixture by the fact that at the mixing stage the phosphorus-containing component is mixed with a solution of the nitrogen-containing component to obtain a suspension with a ratio of N: P ₂ O ₅ : H ₂ O = 1: (0.04-0.7): (0.1-8.9) at a temperature of 70-105 ^o C and the resulting suspension is served on granulation. Ammonium and / or calcium phosphates, phosphorites are taken as a phosphorus-containing component. As a nitrogen-containing component, carbamide, nitrate and / or ammonium sulfate are used. It is also possible to add potassium supplements (potassium sulfate, potassium chloride, etc.).

Granulation of the mixture at a temperature of 60-90 ^o C.

 The essence of the method is as follows.

If a dry mixture is fed to granulation, and then a solution of a nitrogen-containing component is added (according to the prototype), then waterlogging of the particles with a solution that has the ability to agglomerate is observed. In this case, the granules grow rapidly. At elevated temperatures, part of the introduced moisture evaporates quickly enough, as a result, salts crystallize from supersaturated solutions on the surface of solid particles and formed granules. Moreover, in the places of their contact, the formation of larger granules occurs, which significantly reduces the formation of granules with a size of 1-4 mm. When applying the suspension to granulation, in which there are no large particles, this does not happen. The process of granulation is uniform, the formation of large agglomerates is significantly reduced. However, the presence of the liquid phase in the suspension (the amount of H ₂ O) should be strictly regulated so that the output of the granules of the desired size is possibly larger and at the same time, so that its subsequent removal does not lead to an increase in energy consumption. Depending on the phosphorus-containing components used and the nitrogen-containing additive, this amount varies in the range of N: P ₂ O ₅ : H ₂ O = 1: (0.04-0.7): (0.1-8.9).

The temperature of the suspension is selected on the basis of obtaining a certain dissolution rate and the required viscosity of the suspension supplied to the granulation and is 70-105 ^o C.

 The granulation temperature is selected depending on the temperature of the incoming suspension to avoid crystallization of salts and conditions of subsequent drying.

 The method is illustrated by the following examples.

Example 1. 229.73 kg of urea is mixed with water in an amount of 77.43 kg with phosphorite 182.2 kg at a temperature of 80 ^o C. The resulting suspension in an amount of 489.07 kg with a ratio of N: P ₂ O ₅ : H ₂ O = 1: 0.049: 4.23 is fed to granulation of a mixture of potassium chloride 88.1 kg and a retura of 1000 kg; granulation is carried out at a temperature of 60 ^o C. Wet granules are sent for drying. After drying, the product is obtained in an amount of 1500 kg, which contains 70% of the commercial fraction.

Example 2. 21.3 kg of ammonium sulfate is mixed with water in an amount of 39.52 kg with phosphorite 97.87 kg at a temperature of 90 ^o C and get 158.69 kg of suspension with a ratio of N: P ₂ O ₅ : H ₂ O = 1 : 0.7: 8.9. The suspension is fed to granulation of a mixture of phosphorite in an amount of 881 kg and a retur of 800 kg; granulation is carried out at a temperature of 90 ^o C, maintaining the temperature of the mixture by supplying steam. The wet granules are dried and get 1800 kg of dry material, which contains 90% of the product fraction of the product.

Example 3. 591.76 kg of ammonium nitrate is mixed with water 31.4 kg and ammonium phosphate 109.35 kg, obtaining a suspension with a ratio of N: P ₂ O ₅ : H ₂ O = 1: 0,049: 0,1. A suspension of 1031.14 kg is fed to the granulation of a mixture of potassium chloride in the amount of 189.53 kg and a retura of 1000 kg; granulation is carried out at a temperature of 70 ^o C. Wet granules are dried and get 2000 kg of dry material, which contains 75% of the product fraction of the product.

Example 4. 150.0 kg of ammonium nitrate and 27 kg of ammonium sulfate are mixed with water 18.1 kg and phosphorite in an amount of 382.8 kg at a temperature of 105 ^o C and get 577.9 kg of a suspension with a ratio of N: P ₂ O ₅ : H ₂ O = 1: 0.09: 1.28. The suspension is fed to granulation of a mixture of ammonium sulfate 243 kg, potassium chloride 185 kg and retur 1500 kg; granulation is carried out at a temperature of 80 ^o C. Wet granules are dried and get 2500 kg of dry product, which contains 80% of the product fraction of the product.

Example 5. 159 kg of ammonium sulfate is mixed with water in an amount of 238.48 kg and calcium phosphate (superphosphate) 126.4 kg at a temperature of 90 ^o C. The suspension is fed to a granulation mixture of ammonium sulfate 371 kg, calcium phosphate 126.3 kg, sulfate potassium and retura 500 kg; granulation is carried out at a temperature of 80 ^o C. Wet granules are dried and get 1500 kg of dried product containing 85% of the commercial fraction.

 Using the proposed method will allow to obtain granular phosphorus-containing complex mixed fertilizers in a wide range and increase the yield of the finished product fraction to 70-85%.

Claims (4)

1. A method of producing granular phosphorus-containing complex-mixed fertilizers, comprising mixing a phosphorus-containing component with a nitrogen-containing additive and subsequent granulating the mixture at an elevated temperature, characterized in that the phosphorus-containing component is mixed with a solution of the nitrogen-containing component to obtain the ratio N: P ₂ O ₅ : H ₂ O = 1 : (0.04 - 0.7): (0.1 - 8.9) at 70 - 105 ^o C and the resulting suspension is fed to granulation.  2. The method according to claim 1, characterized in that ammonium and / or calcium phosphates, phosphorites are taken as the phosphorus-containing component, and ammonium nitrate and / or ammonium sulfate, urea are used as the nitrogen-containing component.  3. The method according to PP.1 and 2, characterized in that when mixing add a potassium-containing additive. 4. The method according to PP.1 to 3, characterized in that the granulation of the suspension is carried out at 60 - 90 ^o C.