The critical role of extrusion granulators in pellet production

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The critical role of extrusion granulators in pellet production, pharmaceutical, and chemical industries due to their large-scale production capacity, granule fineness, and average size. This article explores the principles, advantages, application areas, and selection and operation of extrusion granulators, providing a practical guide to help you select and use the extrusion granulator that suits your needs and improves the efficiency and quality of granule production.

The critical role of extrusion granulators in pellet production

 

The critical role of extrusion granulators in pellet production

An extrusion granulator is indispensable for producing pellets that are widely used in feed, pharmaceutical, chemical, and other industries. Its excellent performance and flexibility make mass production of high-quality pellets possible.

Critical steps in the production of pellets

  • Raw material pulverization: The raw material is pulverized into fine particles to increase the surface area, which is conducive to subsequent granulation.
  • Mixing: The crushed raw materials are combined with additives to ensure uniformity of the pellet composition and to increase the nutritional value of the feed or the effectiveness of the drug.
  • Extrusion pelletizing: The mixture is compressed and shaped by an extrusion pelletizing machine to form pellets with certain hardness and density.
  • Cooling and drying: The pellets are cooled and dried to reduce moisture content and improve storage stability for subsequent processing.

Advantages of Extruder Pelletizer

  • Increased feed utilization: feed in pellet form is easier to digest than powdered feed, reducing feed waste and improving feed conversion rates.
  • Enhanced efficacy: Granulation protects the active ingredient, prolongs the release time, and improves the absorption rate of the drug.
  • Improve mobility: Granules have good mobility, are easy to transport and store, and are convenient for automated production line operation.
  • Reduce production cost: Extrusion granulator has a high-efficiency production capacity, reducing unit production cost.

 

Principle and mechanism of extrusion granulator

An extrusion pelletizer is a machine that converts powder or granular materials into dense and homogeneous pellets. The principle of operation is based on the following steps:

  1. Material preparation: The powder or granule material is fed into the preheating section of the pelletizer, where it is heated and humidified to increase its plasticity.
  2. Extrusion: The heated material enters the extrusion section, where a pair of rotating screw shafts extrude it. The design of the shaft groove will compress the material and form a continuous strip.
  3. Cutting: When the material is discharged from the extrusion section, it comes into contact with fixed blades and is cut into pellets of a specific length.
  4. Drying and cooling: The cut pellets enter a drying chamber where a fan blows hot air or other media through the pellets to remove moisture and reduce their temperature.
  5. Sifting and sorting: The dried pellets are sifted by a sieve or other sorting equipment to remove any oversized or undersized pellets and to ensure that the final pellets are of uniform size.

The extruder’s mechanism involves several physical processes, including Plastic deformation of the material. The material is plastically deformed during extrusion, causing it to flow and form a continuous strip. Shear: The rotating screw shaft exerts a shearing force on the material, destroying its particle structure and promoting plastic deformation. Frictional heat: The friction between the screw shaft and the material generates heat, which increases the temperature of the material and improves its plasticity. Cooling: The particles are rapidly cooled after they are discharged from the drying chamber, allowing them to solidify and retain their shape.

 

Types of Extrusion Pelletizing Machines and Their Applications

Extrusion pelletizers are classified into various types according to their design and application areas. Choosing the correct kind of pelletizer is critical to meeting specific production needs.

Ring mold extrusion granulator

  • Principle: The material passes through the mold with ring-shaped holes under high pressure to form cylindrical pellets. Application: Widely used in feed, fertilizer, chemical, and pharmaceutical industries to process various materials such as grains, feed additives, chemicals, and pharmaceuticals.

Flat Die Extrusion Granulator

  • Principle: The material is pressed between two parallel flat dies with specific shaped holes to form granules. Application: Mainly used for producing high-density, high-hardness pellets, such as refractory materials, ceramics, and certain chemical products.

Wedge Extrusion Granulator

  • Principle: The material is extruded between two intersecting wedge-shaped rotors to form wedge-shaped pellets. Application: Suitable for processing viscous, deformable, or high-shear materials such as pulp, biomass, and certain chemical products.

Granulator

  • Principle: The material is rolled on a cylindrical body and pressed into pellets using extrusion rollers—application: Commonly used for dense or wet materials such as food, pharmaceutical, and chemical products.

Twin Screw Extrusion Granulator

  • Principle: The material is extruded and heated between two parallel rotating screws to form molten pellets. Application: Mainly used for producing heat-sensitive or uniformly mixed pellets, such as plastics, pharmaceutical, and food industries.
Types of Extrusion Pelletizing Machines and Their Applications
TypePrincipleApplication
Ring die extrusion pelletizing machineThe material passes through a ring-shaped perforated mold to form cylindrical particles.Feed, fertilizer, chemical, pharmaceutical, and other industries
Flat Die Extrusion Pelletizing MachineGranules are formed between parallel flat molds.Refractories, ceramics, and chemicals
Wedge Extrusion PelletizerThe material forms wedge-shaped pellets between intersecting wedge-shaped rotors.Pulp, biomass, and chemicals
GranulatorGranules are formed by rolling the material over the cylinders and through the extrusion rollers.Sticky or wet materials, e.g., foodstuffs, pharmaceuticals, and chemicals
Twin Screw Extrusion GranulatorMolten pellets are formed by squeezing and heating the material between parallel rotating screws.Heat-sensitive or homogeneous particles, e.g., in the plastics, pharmaceutical, and food industries.

 

Advantages and Limitations of Extrusion Pelletizing Machine

Extrusion pelletizers have several advantages that make them ideal for mass production of pellets:

  • High production capacity: The extruder can produce many pellets per hour to meet mass production requirements.
  • Excellent pellet quality: The pellets produced by the extruder have uniform size, shape, and density, meeting stringent quality standards.
  • High efficiency: The extrusion pelletizer is automated and highly efficient, reducing production time and labor costs.
  • Suitable for a wide range of materials: Extrusion pelletizers can process a wide range of organic and inorganic materials, extending their range of applications.

Despite its many advantages, the extruder also has some limitations:

  • High energy consumption: Extruder pelletizers require a large amount of electricity to operate, which can increase production costs.
  • Wear and tear: Mechanical components in an extruder work under high pressure, which can lead to wear and tear and maintenance costs.
  • Pellet Size Limitations: The pellet size produced by an extruder is limited by the machine’s specifications and may not be suitable for specific applications.
  • Thermally sensitive materials: High temperatures during the extrusion pelletizing process may damage thermally sensitive materials, limiting their application.

 

Critical Parameters of Extrusion Pelletizer

The performance and productivity of an extruder pelletizer is affected by a variety of critical parameters, including:

Screw design and construction

  • Screw diameter, pitch, and thread shape affect the size, shape, and quality of the pellets.
  • The choice of screw material also affects durability and wear resistance.

Mold Design and Hole Opening

  • The diameter, shape, and arrangement of the holes in the mold determine the final size and shape of the particles.
  • The choice of material for the · mold is also critical, as it must withstand high pressures and temperatures.

Feed rate

  • The feed rate of the raw material affects the pelletizer’s capacity and the pellets’ quality.
  • Too fast a feed rate may result in overcrowding or clogging of the pellet. ·

Compression ratio

  • The compression ratio refers to the pressure to which the material is subjected in the pelletizer, which affects the density and strength of the pellets.
  • Excessive compression ratios may result in pellet breakage.

Temperature

  • The temperature generated during the pelletizing process affects the properties of the raw material and the quality of the pellets.
  • Excessive temperatures may cause deterioration of the raw material or scorching of the pellet surface.

Moisture content

  • The moisture content of · feedstock affects the pellets’ viscosity, molding ability, and drying time.
  • Excessive moisture content of · may cause softness or sticking of the pellets.

Careful consideration of these critical parameters is essential to optimize the extruder’s performance and ensure the optimum quality of the pellets. By adjusting these parameters, it is possible to adapt the extruder to different raw materials and applications and produce pellets that meet specific requirements.

→More detailed information**Single-stage granulation**

 

Conclusion

Through a thorough understanding of the functional principle of extrusion pelletizers, various industries can now produce large quantities of pellets efficiently and economically. These state-of-the-art machines ensure excellent pellet quality and allow flexible pellet size adjustment for different applications. As extrusion pelletizing technology continues to advance, we look forward to seeing even more innovative and efficient solutions in the future, moving the field of pellet production forward to meet the industry’s ever-changing needs.

 

FAQ

What are the applicable materials of the Extrusion Granulator?

  • Extruder granulators are suitable for all powder or granular materials, such as feed, fertilizer, pharmaceutical raw materials, ceramic powder, etc. It is especially suitable for processing heat-sensitive or easily oxidized materials.

How do we ensure the stable quality of extruded pellets?

  • The key to ensuring the stable quality of extruded pellets lies in controlling the material’s e temperature, pressure, and moisture content. Adjusting the pelletizer’s parameters can achieve the pellets’ desired size, shape, and hardness.

What is the daily maintenance of the extrusion pelletizing machine?

  • Routine maintenance of the extruder includes regular cleaning of the machine body, inspection of the bearings and drive system, replacement of worn parts, and lubrication of the machine. In addition, regular preventive maintenance is recommended to extend machine life and improve productivity.
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