Carbon based fertilizer is a process of carbonizing (pyrolysis) carbon based raw materials (such as straw, sawdust, fruit shells, etc.) into biochar, and then processing it into granular carbon based fertilizer, combining the stability and fertilizer function of biochar. The following is the detailed production process:

1. Raw Material Selection & Carbonization

• Feedstock: High-carbon biomass (e.g., straw, sawdust, nut shells) with particle size <5 cm.
• Carbonization: Oxygen-limited pyrolysis at 400–600°C for 1–2 hours, followed by cooling and screening to remove impurities.

2. Biochar Activation & Nutrient Blending

• Activation (optional): Steam/acid/alkali treatment to enhance surface functional groups.
• Nutrient Mix: Blend with NPK compounds, trace elements, and microbial inoculants (e.g., Rhizobium, phosphate-solubilizing bacteria).
• Binder Addition: 3–5% bentonite or starch to improve pellet integrity.

3. Grinding & Mixing

• Grinding: Milling biochar and additives to 80–100 mesh (≤0.15 mm).
• Blending: Twin-shaft mixer for ≥10 minutes to ensure homogeneity.

4. Granulation

• Double-Roller Extrusion:
  • Moisture content 15–20%, roller pressure 8–12 MPa, die holes 3–5 mm with knife chopper.
• Pan Granulation (alternative):
  • Moisture content 25–30%, 5–8% bentonite, disc angle 45–50°, speed 8–12 rpm.

5. Drying & Cooling

• Drying:
  • Rotary Dryer: 80–100°C for 20–30 minutes, reducing moisture to ≤8%.
• Cooling:
  • Rotary Cooler: Indirect cooling via air/water mist to ambient temperature, protecting microbial activity.

6. Screening & Coating

• Screening: Vibratory sieve to retain 2–5 mm granules, recycling fines to granulation.
• Coating (optional): Spray with humic acid or polymer film for controlled-release.

7. Quality Control & Packaging

• Testing:

  • Nutrient content ≥5% (N+P₂O₅+K₂O), organic matter ≥30%, pH 6–8.
  • Particle strength (breakage <3%), heavy metals compliant with NY 525-2021.

• Packaging: Sealed 25 kg woven bags, stored in dry, shaded conditions.

Key Advantages

1. Soil Health Improvement:
   • Biochar enhances soil Cation Exchange Capacity (CEC), reducing nutrient leaching and improving fertilizer use efficiency.
2. Carbon Sequestration:
   • Stabilizes carbon in soil for centuries, contributing to carbon neutrality goals.
3. Dual Functionality:
   • Combines biochar’s soil-amendment benefits (e.g., water retention, porosity) with targeted nutrient delivery, producing a premium carbon-based fertilizer.

Precautions

1. Carbonization Temperature Control:
   • Maintain pyrolysis temperatures ≤600°C to avoid excessive ash formation (>700°C degrades biochar quality).
2. pH Adjustment:
   • Test biochar pH pre-granulation (typically alkaline, pH 8–10). Adjust to neutral (pH 6.5–7.5) using citric acid if needed to protect microbial activity.
3. Scalability & Quality:
   • Monitor particle size distribution post-screening to ensure uniformity. Validate nutrient coatings for controlled-release under field conditions.

Application Scenarios

• Ideal for large-scale production of high-quality carbon-based fertilizers.

• Specifically suited for saline-alkali soil remediation (biochar reduces sodium/chloride toxicity) and organic farming systems (lowers synthetic input reliance).

This translation maintains technical precision while emphasizing actionable insights for manufacturers and end-users. The structure aligns with international standards for agri-material documentation.