RU2111940C1 - Method for production of granulated fertilizers - Google Patents

Abstract

FIELD: production of granulated fertilizers comprising nitrogen, phosphorous, potassium wherein carbamide being used as nitrogen component. SUBSTANCE: method involves mixing of granulated phosphorous and potassium components with carbamide. Thus prepared mixture is heated to 100-140 C, then granules are cooled at rate 30-50 C/min. EFFECT: improved efficiency of the method.

Description

 The invention relates to methods for producing granular fertilizers containing nitrogen, phosphorus, potassium, in which the nitrogen component is introduced in the form of urea. Such fertilizers are widely used in agriculture for a number of crops.

 A known method of producing granular fertilizers by mechanical mixing of phosphorus granular fertilizers (single or double superphosphate, ammophos, diammonium phosphate, etc.) with a granular potassium component (KCl and potassium sulfate) and carbamide. Stuffing is carried out on plants that differ in the type of mixers and the location of the equipment. Installations operate on a periodic or continuous basis.

 Initially, the components are distributed into silos equipped with metering devices for the required composition. In the mixer, the components are mixed and fed to the warehouse after conditioning.

 A disadvantage of the urea-based fertilizer production method is that the mixtures are hygroscopic and caking during storage. During storage, they are prone to moisture due to the release of crystallization water. To improve the physical condition of such fertilizers, it is necessary to introduce neutralizing additives (at least 15% of the mixture weight) into their composition, since urea exhibits high reactivity and will quickly enter into chemical interaction with the components of the mixture, especially containing potassium chloride. (Technology of phosphate and complex fertilizers. M: Chemistry, 1987, pp. 299 - 303).

 The objective of the invention is to obtain granular fertilizers containing nitrogen, phosphorus and potassium using urea as the nitrogen component, which have good physicochemical properties.

The problem is solved in that in the method for producing granular fertilizers, comprising mixing granular phosphorus and potassium components with urea, the mixture is heated at a temperature of 100-140 ^o C and the granules are cooled at a speed of 30-50 ^o C / min.

 As the phosphorus component, any ammonium phosphates or mixtures can be used.

 As the potassium component can be used potassium sulfate, as well as potassium chloride. Upon receipt of the fertilizer, ballast (limestone) may be added.

 The essence of the method is as follows.

 When granular components having individual physicochemical and mechanical properties are mixed, an uneven distribution of components occurs even in the so-called balanced mixtures, which leads to an overabundance or deficit of one of them at different points in the volume.

Heating the mixture during granulation causes the urea to melt, which, having high reactivity, quickly enters into chemical interaction with the constituent parts of the mixture. As a result, during this process, a single granule is formed, which includes all the components of the mixture, which makes the resulting product uniform in composition throughout the volume. In this case, the heating temperature of the mixture should be strictly defined, since when the temperature drops below 100 ^o C, the viscosity of the eutectic is too high (more than 200 cPs), which complicates the granulation process and does not allow to obtain uniform granules. When increasing it above 140 ^o C there is a significant release of ammonia and urea (above 5%).

Of great importance for obtaining a finished product of uniform composition with good physicochemical properties is the cooling rate. When the cooling rate is less than 30 ^o C / min, coalescence of the granules and the formation of a substandard product.

With an increase in the cooling rate above 50 ^o C / min, the energy consumption and large dust extraction unreasonably increase.

 The implementation of the method in the proposed manner allows to use not only potassium sulfate, but also chloride as the potassium component, since hygroscopic ammonium chloride does not form.

Example 1. 89.8 kg / h of ammophos granules, 660.2 kg / h of granular urea, 106 kg / h of KCl and 167.2 kg / h of ballast (limestone) are respectively loaded into hoppers. The components from the hoppers are fed to a drum-type mixer-granulator. The mixture is heated by flue gases to 100 ^o C. The granulated charge is fed to a fluidized bed refrigerator for cooling, where it is cooled at a speed of 30 ^o C / min to a temperature of 45 ^o C, then the product is classified, conditioned and sent to the warehouse. The result is 1000 kg / h of the finished product of the brand N: P ₂ O ₅ : K ₂ O = 30: 4.6: 6.0. The strength of the granules is 40 kg / cm ² when the content of the fraction of 2 to 4 mm is not less than 90%.

Example 2. In the hoppers respectively load 1000 kg / h of diammonium phosphate (granular), 610 kg / h. granular urea and 770 kg / h KCl. The components from the hoppers are fed to a drum-type mixer-granulator. The mixture is heated by flue gases to 120 ^o C. The granulated charge is fed to a fluidized bed refrigerator for cooling, where it is cooled at a speed of 40 ^o C / min to a temperature of 50 ^o C. The product is then classified, conditioned and sent to a warehouse. The result is 2380 kg / h. the finished product of the brand N: P ₂ O ₅ : K ₂ O = 19:19:19. The strength of the granules is 45 kg / cm ² when the fraction content is not less than 90%. (2 - 4 mm).

Example 3. 320 kg / h of granular diammonium phosphate, 680 kg / h of granular ammophos, 1200 kg / h of potassium sulfate and 770 kg / h of granular urea are respectively charged into hoppers. The components from the bunkers enter the mixer - a granulator of a drum type. The mixture is heated with flue gases to 140 ^o C. The granulated charge is fed to a fluidized bed refrigerator for cooling, where it is cooled at a speed of 50 ^o C / min to a temperature of 45 ^o C. The product is then classified, conditioned and sent to the warehouse. The result is 2970 kg / h of the finished product of the brand N: P ₂ O ₅ : K ₂ O = 16:16:16. The strength of the granules is 42 kg / cm ² when the content of the fraction of 2-4 mm is 90%.

 Using the proposed method will allow to obtain granular fertilizer based on urea, non-tracking, non-hygroscopic, with a sufficiently high strength of the granules. In this case, the finished product yield is at least 90%.

Claims (1)

A method of producing granular fertilizers, comprising mixing granular phosphorus and potassium constituents with urea, characterized in that the resulting mixture is heated to 100 - 140 ^o C, and then the resulting granules are cooled at a speed of 30 - 50 deg./min.