Ring Die Pelleting Machine
Equipment Overview
The dual-die pelleting machine (also known as a ring die pelleting machine) is one of the core pieces of equipment in the field of organic fertilizer, compound fertilizer, and livestock feed pelleting. It integrates the high-pressure molding performance of the traditional ring die granulator with the strong adaptability of the flat die pelleting machine to coarse fibrous materials, representing a deep integration and innovation of fertilizer pelleting technology.
Core Positioning:
1. Primarily used for pelleting (biological) organic fertilizer, compound fertilizer, and livestock feed.
2. Integrates a feeder, mixer, and granulator into one unit.
3. The main unit integrates a ring die and a flat die, equivalent to two granulators working simultaneously.
4. Excellent technology, simple operation, and various models are available.
Technological Evolution: Ring die pelleting technology can be traced back to the 1920s, when the world's first ring die pellet mill was invented. Research on ring die pellet mills in China began in the 1960s, with the first pellet mill imported from UMT in the UK. The first domestically produced ring die pellet mill was developed in the 1970s. Today, the dual-die pelleting machine integrates traditional ring die and flat die technologies, representing a new generation of development direction for granulation equipment.
Raw Material Adaptability of the Equipment
The dual-die pelleting machine/ring die pelleting machine has strong adaptability to raw materials, mainly reflected in:
1. Wide range of raw material moisture content
It can process materials with a moisture content of 20%-50%. High-moisture, viscous materials (such as fermented livestock and poultry manure, sludge, etc.) can be directly granulated without pre-drying.
2. Raw Material Types
Livestock and Poultry Manure: Chicken manure, pig manure, cow manure, sheep manure, etc. (fermentation materials)
Agricultural Waste: Straw powder, corn stalks, rice straw, cotton stalks, etc.
Industrial Organic Waste: Distillers' grains, soybean residue, mushroom residue, medicinal residue, sugar mill filter mud, papermaking sludge, etc.
Urban Organic Waste: Domestic sewage sludge, kitchen waste, etc.
Natural Organic Materials: Peat moss, humic acid, etc.
3. Raw Material Pretreatment Requirements
Fermentation and composting treatment is required first.
Ensure no hard impurities such as metal or stones are present before feeding.
For muddy materials with extremely high moisture content (>50%) and no binding properties, simple dehydration or the addition of straw powder, rice husks, or other auxiliary materials is recommended.
Materials need to be crushed to a suitable particle size to avoid excessive volume.
Applications of the Equipment
The dual-die pelleting machine/ring die pelleting machine is widely used in the following fields:
Bio-organic fertilizer industry: Used for the deep processing of animal manure, crop straw, kitchen waste, and other waste.
Compound fertilizer industry: Suitable for granulation of urea, phosphate, potash, and other mineral fertilizers.
Feed processing industry: Used for the pelleting production of livestock and poultry feed and aquatic feed.
Other biomass pellet processing: Can be used to process wood chips, sawdust, bamboo powder, shell powder, etc.
Equipment Structure and Components
The dual-die pelleting machine/ring die pelleting machine boasts a scientifically designed and multifunctional structure, primarily comprising the following components:
1. Feeding Device: Equipped with a frequency converter, allowing precise adjustment of the feeding speed based on the raw material's moisture content.
2. Mixing Device: Features a built-in secondary mixing function to ensure uniform material distribution and prevent clogging.
3. Ring Die and Flat Die System: Innovatively integrates ring and flat dies to adapt to production requirements of different particle diameters.
4. Pressure Roller System: Equipped with corrosion-resistant, high-strength pressure rollers to ensure stable pressing effects and extend service life.
5. Power System: Driven by a main motor and supplemented by gear transmission, ensuring smooth operation.
6. Adjustment System: Includes a die gap adjustment device for easy control of particle forming effects and to meet the needs of different materials.
Equipment Working Principle
1. Ring Die Pelleting Machine Principle
Driven by a motor, the ring die assembly rotates, and the pressure roller, as the driven wheel, follows suit. Material between the die rollers is forced out of the die holes under pressure and cut into granules by the granulator cutter. The material volume within the extrusion zone is gradually compressed during the roller rotation, finally overcoming the friction between the material and the die hole wall to extrude it from the ring die.
Three-Zone Theory: Based on the state of the powdered material under die roller extrusion, it can be divided into three working zones:
Feeding Zone: Material enters the gap between the die rollers and is initially distributed.
Deformation and Compression Zone: Material is gradually compressed, reducing its volume.
Extrusion Forming Zone: Material overcomes the friction with the die hole wall and is extruded into shape.
2. Flat Die Pelleting Machine Principle
Material enters from the feed hopper and is driven by the main motor, which rotates the flat die disc via a reducer and transmission mechanism. The pressure roller mounted on the drive shaft works in opposite directions with the flat die disc. Under pressure, the material is pressed into the die holes on the flat die disc and compacted into shape. The formed granules are cut and scraped out from the bottom of the die hole by a scraper, achieving continuous granulation.
3. Dual-Die Synergistic Working Principle
The dual-die pelleting machine/ring die pelleting machine integrates the pressing functions of a ring die and a flat die:
Ring Die Section: Utilizes centrifugal force for forced feeding, suitable for large-volume, high-capacity production.
Flat Die Section: Utilizes gravity for vertical feeding, suitable for coarse fiber and high-viscosity materials.
Synergistic Effect: One machine simultaneously leverages the advantages of both modes, adapting to different raw material characteristics; its capacity is equivalent to two single-machine units.
Granulation Process of the Equipment
1. Key Process Parameters
| Parameter | Control Range | Influence |
|---|---|---|
| Die Hole Diameter | Φ2-Φ20mm | Determines the diameter of finished pellets |
| Die Hole Length-Diameter Ratio (Compression Ratio) | Adjust according to material characteristics | Affects pellet density and pelleting rate |
| Ring Die Rotation Speed | Linear speed at inner diameter: 4-8m/s | Excessively high speed reduces pelleting rate; too low speed hinders forming |
| Die-Roller Gap | 0.1-0.3mm | Excessively large gap causes poor forming; too small gap easily leads to machine blockage |
| Material Moisture Content | 15-25% | Excess moisture causes die blockage; insufficient moisture results in failed forming |
| Pellet Temperature Rise | ＜30°C | Excess temperature rise destroys nutritional components of raw materials |
| Pelleting Rate | ＞95% | Core indicator to evaluate granulation performance |
The three factors directly affect the granulation effect: the aspect ratio of the die orifice, the die height, and the die rotation speed. The die rotation speed must be designed reasonably; too high a speed will reduce the granule formation rate, while too low a speed will hinder granule formation.
2. Key Points of Granulation Process for Different Materials
| Material Type | Moisture Control Range | Special Requirements |
|---|---|---|
| Livestock & Poultry Manure | 20-25% | Fully ferment and decompose first, then crush before granulation |
| Crop Straw | 15-18% | Long fiber materials, required to be fully crushed |
| Compound Fertilizer | Adjust according to formula | Pay attention to chemical reaction and moisture of raw materials |
| Biomass Materials | 12-15% | Low inherent moisture, proper humidification is required |
| High-Moisture Materials | Dry to below 20% in advance | Drying equipment can be equipped for pretreatment |
Application of equipment in production lines
Dual-die pelleting machine/ring die pelleting machine is usually used as the core granulation equipment in the organic fertilizer/compound fertilizer production line, located after the fermentation, crushing, and mixing processes, and before the drying, cooling, and screening processes.
1. Typical process of organic fertilizer production line
Selection of raw materials (animal manure, etc.) → Mixing of ingredients → High-temperature decomposition and fermentation of microorganisms → Screening and crushing of semi-finished products → Dual-mode/ring-mold granulation → Drying → Cooling and screening → Measuring and sealing → Storage of finished products
2. Composition of complete equipment
The complete production line mainly consists of fermentation system, granulation system, drying and cooling system, deodorization and dust removal system, and finished product packaging system. The fermentation system includes a feed conveyor, a mixer, a special turning machine, an oxygen supply system and an automatic control system.
3. Unique advantages of dual-mode granulator
In the production line, the dual-die pelleting machine/ring die pelleting machine integrates feeding, mixing, and granulation, reducing the need for intermediate equipment. Dual-mode modules can operate independently and switch on demand to avoid energy waste. The equipment supports continuous feeding and continuous discharging. No special personnel is required. 1-2 people can complete the entire process operation and maintenance.
Operation, Maintenance, and Troubleshooting
Operational Guidelines: Follow the sequence of "start the main unit first, then start the feeder, then add material" and "stop the material first, then stop the feeder, then shut down the machine."
Daily Maintenance:
Pressure Roller Lubrication: Lubricate the rollers every shift during the first week of operation, and add high-temperature grease periodically thereafter.
Die Grinding: New dies need to be repeatedly ground with oil (sawdust + machine oil) to ensure smooth pores.
Common Problem Solutions:
No Particle Production/Clogging: This is usually due to improper die break-in or excessive moisture content. Clean the die pores and adjust the raw material ratio.
Particles Too Fine: Check the material's adhesion; appropriately increase the moisture content or adjust the pressure roller gap (0.1-0.3mm).
Common Equipment Problems and Solutions
| Common Faults | Possible Causes | Solutions |
|---|---|---|
| No pellets output due to blocked die holes upon startup | Rusted and low-smoothness die holes; excessive gap between mold and pressure roller | Clean residual pellets in die holes; grind with high-oil powder; adjust gap to 0.1-0.3mm |
| Excessive powder or failure to form intact pellets | Too high or too low material moisture; excessive crude fiber | Adjust moisture content; add sticky powder materials |
| Gradually reduced output | Excessively large mold-roller gap; low moisture; clogged die holes; abnormal feeder speed | Adjust gap; increase water content; clean molds; inspect feeding machine |
| Hard and glossy pellets | Insufficient moisture of raw materials | Raise moisture content of powder raw materials |
| Soft pellet edges with cracked and sticky surface | Improper moisture ratio; rough new mold plate | Adjust water content; grind by extruding oily powder materials |
| Sudden machine shutdown | Large hard foreign matter or metal stuck between mold and roller | Remove foreign objects; reduce feeding amount |
| Die hole blockage | Uneven & fast feeding; oversized raw material particles; low voltage; over-large compression ratio | Feed evenly; re-crush materials; improve power distribution; replace ring die with proper compression ratio |
| Rough pellet surface | Rough surface of new mold | Perform circulating extrusion running-in with oily raw materials |
Dual-die pelleting machines/ring die pelleting machines are core equipment in the production of organic fertilizers, compound fertilizers, and biomass pellets, achieving high levels of technological maturity, capacity efficiency, and finished product quality. By integrating ring and flat die technologies, dual-die granulators realize a highly efficient "one machine, two uses" production mode, significantly improving raw material adaptability and capacity output while ensuring a high pellet yield (>95%).
Whether you are building a new organic fertilizer/compound fertilizer/feed production line and need a complete equipment solution, upgrading an existing production line and need equipment selection advice, or encountering difficulties in granulating high-moisture, sticky, or coarse-fiber materials and need technical support—we are always ready to provide you with professional and sincere service.
| Model | HP-450 | HP-650 |
| Capacity (t/h) | 2-5 | 4-8 |
| Pelleting Rate (%) | >95% | >95% |
| Motor Power(Kw) | 30+1.5 | 55+3 |
| Dimension(mm) | 2150*1350*2200 | 2500*1350*2535 |
