How to achieve D90 < 10um in rCB grinding?

1.1 Feedstock Quality Improvement

• Secondary Pyrolysis/Devolatilization: Heat rCB at 800–1100°C in a rotary kiln or fluidized bed to remove surface tars, PAHs, and volatile matter (<2.5%), improving grindability
• Impurity Removal:
  • Magnetic separation for iron wire fragments (critical for equipment protection)
  • Screening to remove coarse ash particles (>500μm)
  • Optional acid washing for high-purity applications to reduce ash content

1.2 Pre-Crushing Optimization

• Reduce feed size to ≤10–20 mm using jaw crushers or hammer mills
• Ensure uniform particle distribution to prevent overloading and uneven grinding
• Moisture control: Maintain <1% moisture to avoid agglomeration and ensure efficient air classification

3.1 Grinding Chamber Settings

• Roller Pressure: Increase to 1.2–1.8 MPa for rCB to enhance particle breakage (adjust based on material hardness)
• Rotational Speed:
  • Main shaft: 180–220 rpm for ring roller mills (reduced speed improves particle-to-roller contact)
  • Classifier wheel: 3000–6000 rpm (higher speeds for finer cuts)
• Grinding Media (for ball mills):
  • Use 5–10mm zirconia or alumina balls (avoid iron contamination)
  • Optimize media filling ratio to 60–70% for maximum energy transfer

3.2 Air Classification Parameters (Critical for D90 Control)

• Air Flow Rate: 1200–1800 m³/h (balances particle transport and classification efficiency)
• Air Separation Velocity: Stabilize with sub-Hertz VFD accuracy to precisely control cut-point
• Closed-Loop System: Recirculate oversize particles (≥10μm) back to grinding chamber for reprocessing
• Pressure Differential: Maintain 2–3 kPa across classifier to ensure consistent particle separation

3.3 Operational Controls

• Temperature: Keep grinding chamber <120°C to prevent thermal degradation of rCB structure
• Feed Rate: 1–3 tons/hour (adjust based on mill capacity to avoid under/over-grinding)
• Dust Collection: Use high-efficiency cyclones + bag filters (≥99.9% collection efficiency)

4. Advanced Process Enhancements for D90 < 5μm

4.1 Multi-Stage Grinding Strategy

1. Stage 1: Coarse grinding to D90 = 30–50μm (reduces energy consumption in fine grinding)
2. Stage 2: Fine grinding to D90 = 10–15μm
3. Stage 3: Ultra-fine grinding to D90 < 5μm (optional for high-performance applications)

4.2 Agglomerate Disruption Techniques

• Cavitational Vortex Milling: Uses fluid dynamics to break down hard agglomerates without excessive energy input
• Surface Modification: Add 0.1–0.5% dispersant (e.g., silanes) during grinding to prevent re-agglomeration

4.3 Intelligent Process Control

• Implement online particle size analyzers (e.g., laser diffraction) with real-time feedback to classifier speed and feed rate
• Use AI-driven process optimization to maintain ±0.5μm particle size stability

5. Quality Assurance: Verify D90 < 10μm Consistently

1. Sample Collection: Take representative samples at multiple points (product outlet, classifier overflow, recirculation stream)
2. Particle Size Analysis:
   1. Use laser diffraction (ISO 13320) with appropriate dispersion (0.1% sodium hexametaphosphate)
   2. Measure D10, D50, D90, and Span (Span = (D90-D10)/D50) for PSD characterization
   3. Target Span < 1.3 for narrow particle distribution
3. Process Validation:
   1. Run 3 consecutive batches to confirm D90 consistency (<10μm with <5% variation)
   2. Document all parameters for repeatability (pressure, speed, air flow, feed rate

7. JACAN Tech Solution: Optimized rCB Grinding Package

1. Pre-treatment module: Secondary pyrolysis + magnetic separation + pre-crushing
2. Core grinding: JACAN HGM-1000 Ring Roller Mill with VFD turbo classifier (D97 ≤5μm capability)
3. Quality control: Online laser diffraction analyzer + AI process control
4. Energy efficiency: 30% lower energy consumption vs. traditional jet mills (85–100 kWh/ton at D90=8μm)