NPK fertilizer cooling machine its role in fertilizer production process

There are many production processes for compound fertilizers. Different processes are suitable for different raw materials and production requirements. Common ones include steam drum granulation, disc granulation, spray granulation, high tower granulation, ammoniation granulation and blending. These processes have their own characteristics, which can not only meet the requirements of different fertilizer formulations, but also adapt to diverse market needs, and provide efficient and high-quality fertilizer products for agricultural production. In this article, we will give a brief introduction to these production processes, briefly analyze their advantages and disadvantages and market prospects.

What is compound fertilizer?

Compound fertilizer is a fertilizer that contains at least two nutrients in a specified amount among nitrogen, phosphorus and potassium. It can be made by chemical methods and/or physical processing. Compound fertilizers are products made by chemical methods, such as monoammonium phosphate and S-NPK, while mixed fertilizers are products made by physical mixing methods, such as urea-based fertilizers and BB fertilizers.

What are the raw materials for NPK fertilizer production?

CategoryMaterial NameChemical FormulaKey Content
Nitrogen SourceUrea(NH₂)₂CONitrogen content N≥46%
Ammonium Sulfate(NH₄)₂SO₄Nitrogen content N≥20.8%
Ammonium BicarbonateNH₄HCO₃Nitrogen content N≥17.5%
Ammonium ChlorideNH₄CLNitrogen content N≥25.39%
Ammonium NitrateNH₄NO₃Nitrogen content N≥34.6%
Monoammonium PhosphateNH₄H₂PO₄Nitrogen content N≥10%
Diammonium Phosphate(NH₄)₂HPO₄Nitrogen content N≥13%
Phosphorus SourceOrdinary SuperphosphateCa(H₂PO₄)₂・H₂OP₂O₅ content ≥12%
Triple SuperphosphateCa(H₂PO₄)₂・H₂OP₂O₅ content ≥40%
Monoammonium PhosphateNH₄H₂PO₄P₂O₅ content ≥40%
Diammonium Phosphate(NH₄)₂HPO₄P₂O₅ content ≥38%
Calcium Magnesium Phosphate-P₂O₅ content ≥12%
Nitro Phosphate-P₂O₅ content ≥11%
Potassium SourcePotassium ChlorideKCLK₂O content ≥63.17%
Potassium SulfateK₂SO₄K₂O content ≥54.06%

What is high tower granulation fertilizer production line?

  • High tower granulation involves spraying high-temperature molten raw materials or molten mixtures from a high elevation. During their descent, the materials cool and agglomerate into granules, which are then screened. The resulting granules undergo a high-temperature process, reducing moisture content and making them less prone to caking. This process produces glossy, crystalline granules with excellent appearance. However, it requires high-purity raw materials, leading to its common use in high-concentration fertilizer formulations, often with a higher proportion of urea.
  • Fertilizers produced via high tower granulation are characterized by uniform granules with bright color and distinct small pores visible on the surface—features that distinguish them from fertilizers made through traditional methods like extrusion, drum, or mixing granulation. These distinct pores serve as a visual identifier of high tower fertilizers.
  • Despite their reduced moisture content, high tower granules may still experience hygroscopic caking in humid summer conditions. However, due to their quick solubility, these fertilizers are highly efficient and particularly suitable for use as topdressing fertilizers.
  • However, the fertilizer that is suitable for high tower granulation processing cannot have a low nitrogen content and a high phosphorus content. Usually, the maximum phosphorus content can only be maintained at about 15. Therefore, this process technology can generally only produce high-nitrogen compound fertilizers. In addition, a major disadvantage of this processing technology is that the fertilizer produced by this process has a high biuret content, which is close to the upper limit of the national regulations (1.5%).

What is rotary steam drum granulation method? Pros and Cons

  • Drum granulation is a physical synthesis method that evenly mixes nitrogen fertilizer, phosphate fertilizer, potash fertilizer and filler, and processes them into granular fertilizer through drum equipment. Its main working mode is wet granulation. By adding an appropriate amount of water or steam, the basic fertilizer undergoes a sufficient chemical reaction after being humidified in the drum. Under liquid phase conditions, the drum rotates to generate extrusion force between the material particles and agglomerates into balls.
  • Drum granulation has fewer formula restrictions and has the advantages of low investment, high output and short construction period. Therefore, it is favored by many compound fertilizer manufacturers and is the most widely used process in compound fertilizer production.
  • The process is relatively simple(including grnulator, dryer, cooler, coating machine, rotary drum screener, dedusting system...etc)and can produce products of various specifications, but there are problems such as uneven nutrient mixing (basically uniform), low water solubility and utilization rate, and easy loss. The granules have a general appearance, low hardness, easy powdering and agglomeration, and poor storage resistance, but they can quickly take effect when used as topdressing for crops with a short growth period during drought years.

What is spray drum granulation?

  • Spray granulation is a method of producing fine particles directly from a solution or slurry through evaporation, commonly referring to urea spray granulation. In this process, molten urea is sprayed into a compound fertilizer granulation unit, eliminating the need for urea crushing. Connecting directly to the urea plant's urea solution pipeline can further reduce costs.
  • Fertilizers produced by spray granulation dissolve quickly, but they are mostly high-nitrogen formulas with nitrogen content above 20%. For lower nitrogen content formulas, using urea is unnecessary from a cost-saving perspective, and the process conditions are better suited to drum granulation. High-nitrogen formulas are more cost-effective and produce visually appealing granules. However, compound fertilizers made through spray granulation generally have lower nitrogen content, around 12%, and water-soluble phosphorus levels of about 80%.
  • Although the utilization rate is lower than products made through ammoniation, the technology is mature, and the product qualification rate is high. Spray granulation produces fertilizers with uniform granule size, good anti-caking properties, and a relatively white appearance.

What is the difference between high tower granulation and spray drum granulation?

DifferenceSpray Granulation (Tank Reactor)Ammoniation Granulation (Pipe Reactor)
ReactorTank-typePipe-type
Reaction Time30 minutes, incomplete reaction10 seconds, complete reaction
Neutralization1:1, low absorption efficiency1:5, high absorption efficiency
Nitrogen~13%, single-form nitrogen, produces biuret, risks seedling burn>16%, three-form nitrogen, no biuret, no seedling burn
PhosphorusLong reaction time, generates large amounts of phosphate precipitates, severe degradation, poor water solubilityShort reaction time, no phosphate precipitates, no degradation, water solubility up to 95%
PotassiumChloride ion content ~3%Chloride ion content <3%
MicroelementsCalcium, magnesium, and other microelements in ores must be removed as impuritiesCalcium, magnesium, and other microelements in ores can be retained directly
Technical LevelLoose operating range, low technical requirementsBroad operating range, higher difficulty

What is ammonia granulated compound fertilizer production line?

  • Ammonia granulated compound fertilizer adopts ammoniation and secondary dechlorination granulation production process. Potassium chloride and sulfuric acid are added to the reaction tank for heating and react under specific conditions. The generated HCl gas can be produced with a certain concentration after being absorbed by water. Hydrochloric acid, the potassium hydrogen sulfate produced at the same time is mixed with dilute phosphoric acid to form a mixed acid. The mixed acid and synthetic ammonia react in a tubular reactor in proportion to generate a compound fertilizer slurry, which is directly sprayed into the drum granulator to produce a certain proportion of sulfur-based compound fertilizer.
  • This process has uniform granulation, bright color, sufficient nutrients, easy to dissolve, easy to be absorbed by crops, and stable quality. It is widely used in various types of soil and wheat, peanuts, corn, fruits, flowers, beans, fruit trees, etc. crops and cash crops.
  • The nitrogen content of the compound fertilizer produced through ammonia granulation can reach more than 14%, and the water-soluble phosphorus content can reach more than 95%, with remarkable fertilizer efficiency. Due to its high nitrogen content, this type of compound fertilizer not only meets the growth needs of crops, but also significantly increases crop yield and quality. In addition, the particles produced by this process have irregular shapes and strong resistance to caking, making them easy to store and transport.
  • Ammoniated granulation is actually a spray granulation process. The finished product has the characteristics of uniform nutrients, bright color, stable quality, etc., and is easily absorbed by crops. Especially when used as seed fertilizer, it is relatively safe for seeds and reduces the risks of crop planting. . It is suitable for a variety of crops and economic crops, such as wheat, corn, fruits, peanuts, vegetables, beans, flowers and fruit trees, etc. It can be used as base fertilizer, seed fertilizer or top dressing. Especially when used as a base fertilizer for cash crops, the yield increase effect is particularly significant.

What is disc granulation method?

  • The principle of disc granulation is to mix all the raw materials and send them into the disc granulator, and the materials are agglomerated into spherical particles through the rotation of the disc. This process uses the viscosity and centrifugal force of the material to gradually form and increase the particles to the required size.
  • The main characteristics of disc granulation are uniform product particles, simple equipment structure, low investment cost, and intuitive operation and easy to master. For this reason, this process has been widely used in medium and small compound fertilizer manufacturers, especially for enterprises with small production scale.
  • However, disc granulation also has some shortcomings. It is only suitable for small-scale production and has low production efficiency. In addition, this process has certain restrictions on the formulation of raw materials. It can only be used for slurries or molten materials with low viscosity, and cannot meet the granulation needs of raw materials with high viscosity.

What is bulk blending fertilizer production line?

According to the nutrient ratio requirements, the BB(bulk blending) fertilizer production line uses a variety of solid basic fertilizers of nitrogen, phosphorus, and potassium that do not undergo significant chemical reactions as raw materials. The particle size and roundness of these raw materials are basically the same. Through a certain blending method, these basic fertilizers are formulated into blended fertilizers with even nutrient distribution. The advantage of the blending method is that the processing process is simple, the cost is low, and it is suitable for mass production. However, during production, storage, transportation and use, special attention must be paid to the basic consistency of the size, weight and roundness of the various basic raw material particles. This is to prevent problems such as clumping, crushing and low moisture absorption points in the mixture, ensuring the quality and stability of the fertilizer.

What is the difference between various granulation method?

Granulation ProcessKey Characteristics
Drum GranulationSimple process, but results in smooth granules. The raw material quality varies, leading to inconsistent results.
Water solubility and utilization rate are lower, leading to potential loss.
However, for crops with short growth periods in dry years, the fertilizer effect is faster compared to drum spray granulation.
Drum Spray GranulationHard granules, not easily lost, suitable for base fertilization for crops with long growth periods. Fertilizer effect lasts longer than high tower granulation.
Ammoxidation GranulationSuitable for formulated fertilization, with a fertilizer effect between drum granulation and drum spray granulation. Utilization rate is better than spray granulation but lower than high tower granulation.
High Tower GranulationSmooth, hollow granules with balanced content.
Fastest fertilizer effect among compound fertilizers, highly soluble, and ideal for topdressing.
Disadvantages include the potential for urea melting during spray granulation. If the process time is not controlled well, it may produce large amounts of biuret, and moisture may exceed standards.

Conclusion:

In conclusion, common compound fertilizer production processes include drum granulation, drum spray granulation, ammoxidation granulation, and high tower granulation. Each process offers distinct advantages depending on the specific requirements of the fertilizer, such as particle smoothness, granule hardness, solubility, and release rate. Drum granulation is simple and cost-effective but may lead to inconsistent results. Drum spray granulation produces hard, durable granules, ideal for base fertilization. Ammoxidation granulation strikes a balance in fertilizer efficiency, while high tower granulation provides fast-acting, highly soluble fertilizers suitable for topdressing. The choice of process depends on the crop's needs, growth period, and environmental conditions, as well as the desired fertilizer characteristics. Now which company produces the best fertilizer production equipment? The answer is Tongli Heavy Machinery with 65+ years of experience.