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How Do You Make Granular Fertilizer: The Definitive Guide

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How Do You Make Granular Fertilizer: The Definitive Guide

November 2, 2023 machinery 0 Comments

Chemical fertilizer is a kind of substance that provides essential nutrients for plants and improves soil properties, which is essential for increasing crop yields.

In agricultural production, the lack of any element affects the normal growth and development of crops. For example:

Elements Effects Element deficiency
Nitrogen Promote cell division and growth. The plant is short and thin with yellowish green leaves.
Phosphorus Promote sugar movement, improve drought and cold resistance of the plant. The plant is small, low in sugar with withered seeds.
Potassium Promote photosynthesis, improve cold, disease and lodging resistance of the plant. Crops wither and tissues are soft and prone to lodging.

Agriculture cannot be developed without fertilizers. This article will briefly introduce the fertilizer production process provided by Fote engineers.

Burdening and mixing of the fertilizer ingredients

A horizontal mixer or a disc mixer is used to mix the prepared raw materials evenly to enable the fertilizer efficiency of the fertilizer particles uniform. Uniform mixing of the fertilizer not only refers to the new material alone, such as the nitrogen, phosphorus, and potassium, but the new material together with the returned material.

The ingredients of different fertilizers are as follows:

Nitrogen fertilizer, phosphate fertilizer, potash fertilizer and compound fertilizer (NPK fertilizer)

Nitrogen fertilizer, phosphate fertilizer, potash fertilizer and compound fertilizer (NPK fertilizer)

Raw materials such as urea, ammonium nitrate, ammonium chloride, ammonium sulfate, ammonium phosphate (monoammonium phosphate, diammonium phosphate, coarse whiting, single superphosphate), potassium chloride (potassium sulfate), etc. shall be provided at a certain ratio (according to market demand and soil test results in various regions).

Organic fertilizer

Organic fertilizer

Livestock manure: chicken manure, pig manure, cow manure, sheep manure, rabbit manure, etc.

Crop straw: Crop straw, containing necessary nutrients for crops such as N, P, K, Ca, S, etc., is one of the important fertilizer ingredients.

Household garbage: leftovers, water of washing rice, discarded fruits and vegetables, expired dairy products and food, etc.

Cake fertilizer raw materials: rapeseed cake, cottonseed cake, bean cake, sesame cake, castor cake, tea seed cake, etc.

Sludge manure: unpolluted river mud, pond mud, ditch mud, harbor mud, lake mud, etc.

Note: The organic fertilizer should be fermented for 15-20 days before crushing.

Crushing of chemical fertilizer

Fote roller crusher, hammer crusher, double stage crusher and compound crusher are all suitable for the crushing of various medium hardness materials in the production of compound fertilizers, organic-inorganic compound fertilizers and organic fertilizers.

Fote roller crusher, hammer crusher, double stage crusher and combination crusher

Fote roller crusher, hammer crusher, double stage crusher and combination crusher

Fote crusher, with the characteristics of high-quality wear-resistant steel, reasonable design of inlet and outlet and easy to clean, can evenly crush the fertilizer and the fertilizer is not easy to stick to the wall.

Chemical fertilizer crusher price: Get Latest Price

Granulation of the fertilizer

Fote disc granulator

The purpose of fertilizer granulation is to adjust the composition of fertilizer and provide the required nutrients according to the crop types and growth stages.

It can prevent ingredients separation, dust loss during fertilization and solidification due to hygroscopic and heavy pressure during storage, improve fertilizer performance and extend fertilizer efficiency.

The rolling granulation equipment commonly used in the fertilizer industry is divided into disc granulation, rotary drum granulation and spraying granulation according to the types of granulation containers.

Chemical fertilizer granulator price: Get Latest Price

Disc granulation

Rolling granulation can be carried out by placing fertilizer in a disc granulator’s tilting rotating plate and adding water or a granulating accelerator (liquid) as appropriate.

Fote disc granulator has a simple structure, less investment and simple operation, which is more suitable for medium-sized enterprises.

Advantages of Fote disc granulator:

  • Simple structure, convenient operation and maintenance. In particular, since the granulation in the disc can be directly seen, the replacement and adjustment are convenient and quick.
  • It has a classification effect. When the required particle size is reached, it automatically pops out from the edge of the disc. The particle size of the product is relatively uniform.
  • The product has high particle strength and good quality. Because the particles in the rolling and falling process gradually increase, it is not easy to be crushed with high density and smooth surface.
  • The price is low with small installation area. In the case of the same output, the price of Fote disc granulator is two-thirds and the required installation area is about half that of the rotary drum granulator.

Rotary drum granulation

Drum granulator

The material forms a rolling bed after entering the rotary drum granulator as the cylinder continuously rotates.

Under the effect of extrusion pressure, the material aggregates into small particles surrounded by powder, and then forms 3-4 mm qualified spherical particles which are finally discharged through the discharge end.

Rotary drum granulator is one of the most widely used equipment in fertilizer production, however, its cost is higher and the required installation area is larger compared with the disc granulator.

Advantages of drum granulator:

  • The granulation rate can be as high as 70%. Therefore, it is suitable for large-scale fertilizer production.
  • The lining, made of rubber engineering plastics, can effectively eliminate the adhesion between the raw material and the inner wall of the drum.
  • Particles grow during rolling and have spherical or nearly spherical shapes with smooth surfaces.
  • The fertilizer particle size is easy to control.

Spraying granulation

Spraying granulation

Spraying granulation refers to the process in which the water (general term for vaporizable liquid) in the slurry (mixture, solution and solute) is vaporized and separated by heating and pumping after being sprayed into a device, while the retained solid that will not vaporize (under certain conditions) is formed into granules.

Advantages of spraying granulation:

  • Fertilizer has no side effects and will not produce harmful substances under the action of soil aqueous solution, soil minerals and biological bacteria.
  • Fertilizer can rapidly combine or activate the original soil that has been solidified or derived into citric acid soluble phosphorus, caustic potassium and medium trace elements in the soil, so as to improve the high utilization rate of itself and soil nutrients.
  • Fertilizer is very effective to purify the soil environment, especially to deal with the rich oxidation problem of soil aqueous solution.

Drying of the fertilizer

The drying part is indispensable in the process of fertilizer production, which directly affects the yield, quality and energy consumption.

Drying of the fertilizer

Drying of the fertilizer

Fote dryer not only has the function of drying, but also has the function of secondary granulation. The material in the dryer can increase the solubility of its original moisture to the fertilizer by increased temperature. The granular fertilizer formed by this liquid phase plays a role in improving the yield with the characteristics of high pelletizing rate, uniform particle size, low water content and easy to dry.

Fote dryer is equipped with the guide area, secondary granulation and polishing area, 180° pre-drying area, 135° drying area, 135°/120° staggered drying area, 120° drying area and 120°/90° staggered drying area at the exit, which can not only ensure that the wet and soft particles are not damaged after granulation, but also improve the drying efficiency.

The water containing of the finished product after drying is preferably 1.0% to 1.5%. The optimal temperature difference between the head and tail of Fote dryer is about 100 ℃. Exhaust gas temperature, the focus of operation, should be generally controlled at 65-80 ℃ with the positive and negative deviations of 1 ℃.

Chemical fertilizer dryer price: Get Latest Price

Cooling and screening of fertilizers

The dried material will be transferred to the cooler for cooling by the belt conveyor. The cooling process mainly uses the blower to send the natural air through the pipe to the cooler to cool the material.

The cooled material will be transferred to the trommel screen for screening. The crushed large particle material and the unqualified powder will be returned to the Fote granulator through the conveyor for re-granulation while the qualified fertilizer particles will be transported to the automatic packaging system for packaging.

Chemical fertilizer screen price: Get Latest Price


Advanced production technology of Fote Machinery

Advanced production technology of Fote Machinery

The chemical fertilizer production process generally includes several steps: ingredients batching and mixing, crushing, granulation, drying, cooling and screening. This is just a brief introduction of some simple chemical fertilizer production process flow. If necessary, please contact Fote Machinery directly and we provide equipment for the fertilizer production line.

FAQ about fertilizer (compound fertilizer and organic fertilizer) granulation process

1. What are the requirements for compound fertilizer formula design?

① The viscosity of the material in the formula is the basis of granulation.

  • When low concentration fertilizer is produced by using superphosphate as the phosphorus source, the conditioning agent of superphosphate and viscous material should be greater than 50%.
  • When high-concentration compound fertilizer is produced by using ammonium phosphate as the phosphorus source, the conditioning agent of ammonium phosphate and viscous material should not be less than 40%.
  • Urea formula depends on the amount of urea. The proportion of viscous materials in high-viscosity urea is generally about 35%.

② The ingredients used in the formula must be conducive to improving the roundness of the particles.

The decomposition and softening temperature of dispersive materials (potassium chloride, ammonium chloride, potassium sulfate, ammonium sulfate, etc.) is relatively high, which can increase the strength of the particles in the dryer and play a key role in improving the roundness of the particles. The sum of dispersible materials in the formula should account for more than 35%.

2. How long does the fertilizer stay in the dryer?

The residence time of materials in the dryer should be generally greater than 22 min. Under the same condition, the longer the dryer barrel, the longer the material residence time and the higher the heat energy utilization ratio.

Fote dryer

Fote dryer

Therefore, lengthening the dryer barrel is very beneficial to make full use of thermal energy. It is an effective way to solve the problem that the setting of granulation and pelletizing area affects the drying function.

3. What is the most suitable drying temperature during organic fertilizer processing?

To avoid the death of effective live bacteria due to excessive temperature during the drying process, the drying temperature of the material should not be higher than 60 ℃ (generally 50 ℃).

For this reason, the temperature of the hot air in contact with the material should be different according to the moisture content of the material, generally no more than 130 ℃, so that the hot air temperature can be controlled in sections to improve the thermal efficiency as well as avoid the death of effective live bacteria.

4. What are the factors that affect the granulation of fertilizer disc granulators?

The main factors influencing the granulation of fertilizer disc granulator are mainly the diameter of the disc, the height of the side of the disc, the inclination of the disc, the rotating speed and the water addition.

Fote fertilizer disc granulators

Fote fertilizer disc granulators

The ratio of side height and diameter of the disc granulator is generally 0.12-0.17. Its diameter can be calculated from the production intensity obtained from the test or actual production assessment.

The inclination of the disc granulator is determined according to the natural angle of repose of the wet powder before granulation. For example:

The natural angle of repose of potassium chloride is 36°; dipotassium phosphate is 31°; coarse whiting is 31°-35°.

When the inclination is less than the natural angle of repose of the wet powder, the material will stick to the disc; however, as the inclination increases, the rotation speed increases, the material residence time becomes shorter, and the overflow particle size becomes smaller, so it should be determined according to specific conditions, generally 40°-60°.

Increasing the disc rotation speed can increase the granulation rate of fertilizers.

As the amount of water added increases, the granulation rate of fertilizer first increases and then decreases. The smaller the particle size of raw materials, the higher the granulation rate.

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