I. Core Influencing Factors Analysis

1. Pelletizing Equipment Parameters
   • Disc Pelletizer: Adjust disc inclination angle (typically 35°~55°) and rotation speed (20~40 rpm) to control material rolling intensity and duration.
   • Extrusion Pelletizer: Select die hole diameter (common 2~8 mm) to directly determine base particle size.
   • Roller Press Pelletizer: Adjust roller gap (1~5 mm) and pressure to control particle density and size.
2. Raw Material Characteristics Control
   • Raw Material Granularity: Crush raw materials (animal manure, straw, etc.) to <2 mm, with fine powder content >70% to enhance pellet formation rate.
   • Moisture Content: Maintain material humidity at 25%~35% (adjusted per raw material type) through precise water spraying.
   • C/N Ratio and Organic Matter: Keep C/N ratio at 20:1~30:1 and organic matter content >30% to improve binding properties.
3. Additive Application
   • Binder: Add starch, humic acid (1%~3%) or bentonite (2%~5%) to enhance particle strength.
   • Porosity Agent: Incorporate rice husk powder or straw碎屑 (5%~10%) to prevent particle caking.
4. Screening and Recycle System
   • Multi-Layer Vibrating Screen: Equip 2~4 layers of screens (e.g., 4 mm, 6 mm, 8 mm) to separate unqualified particles.
   • Recycle Process: Return <4 mm fines and >8 mm oversized particles to the pelletizer for reprocessing.

II. Step-by-Step Control Scheme

Step 1: Raw Material Pretreatment

• Crushing: Use hammer mills to pulverize raw materials to particle size <2 mm.
• Mixing: Homogenize raw materials and additives via twin-shaft mixers to ensure consistent C/N ratio and moisture.

Step 2: Pelletizing Process Adjustment

• Disc Pelletizer:
  • Increasing inclination angle or rotation speed reduces particle size (and vice versa).
  • Example: For 4~6 mm particles, set 45° inclination and 30 rpm.
• Extrusion Pelletizer:
  • Replace die holes with target size (e.g., 5 mm) and adjust extrusion pressure to ensure particle integrity without crushing.

Step 3: Moisture and Temperature Control

• Dynamic Water Supplement: Use雾化 devices to maintain surface moisture during pelletizing.
• Drying Regulation: Control fluidized bed drying temperature at 60~80℃ to avoid particle cracking from overheating.

Step 4: Screening and Quality Control

• 分级 Screening:
  • Primary screen (6 mm): Separate oversized particles for recycling.
  • Secondary screen (4 mm): Remove fines to mix with fresh raw materials.
  • Qualified products (4~6 mm) proceed to cooling and packaging.
• Quality Inspection: Conduct batch testing for particle hardness (>10 N), moisture content (<8%), and size distribution.

III. Common Issues and Solutions

IV. Equipment and Cost Optimization

• Automation Control: Install online moisture detectors and particle size analyzers for real-time parameter adjustment.
• Energy Reduction: Use heat recovery systems to preheat raw materials with drying exhaust, reducing energy consumption by 15%~20%.
• Custom Dies: Tailor extruder dies to target particle size, minimizing screening waste.

This scheme enables precise control of organic fertilizer particle size (error ±1 mm), achieving >90% finished product rate while reducing recycle processing costs.