High-Efficiency OCC Recycling Line for Corrugated Paper Production

High-Efficiency OCC Recycling Line for Corrugated Paper Production

Corrugated medium and testliner production relies on recycled OCC (Old Corrugated Containers) as the primary fiber source. A modern OCC recycling line must handle high contamination levels — including staples, tape, plastics, and wet-strength paper — while delivering consistent pulp quality at the lowest possible energy cost. The key performance indicators are fiber yield (target above 92%), specific energy consumption (below 30 kWh per ton for the complete OCC system), and final pulp cleanliness (TAPPI dirt count under 50 ppm for medium grades).

Drum Pulper vs. Hydraulic Batch Pulper for OCC

For production capacities above 300 TPD, the drum pulper offers distinct advantages over batch hydraulic pulpers for OCC processing. The continuous rotating drum design provides gentle defibering action that preserves fiber length while the screening section (perforated with 8-12 mm holes) continuously removes contaminants:

• Drum pulper: 300-1,200 TPD capacity, 15-18% operating consistency, specific energy 15-18 kWh/t, fiber loss under 3%
• Hydraulic batch pulper: 200-600 TPD, 4-6% consistency, specific energy 22-28 kWh/t, fiber loss 4-6%

The drum pulper achieves approximately 30-35% lower specific energy than batch hydraulic pulpers because the defibering action comes from stock-to-stock friction (not rotor impact). Additionally, the continuous discharge eliminates the pump-out cycle energy spike. For a 500 TPD OCC line, the drum pulper saves approximately 5,000-55,000 annually in electricity costs alone.

High-Density Cleaning and Coarse Screening

After pulping, the stock passes through high-density (HD) cleaners that remove heavy contaminants — stones, sand, metal fragments, and glass — operating at 3-4% consistency. This is followed by coarse screening to remove large lightweight contaminants:

• HD cleaner: 2.0-2.5 bar pressure drop, reject rate 3-5%, removes particles above 2.0 specific gravity at 95%+ efficiency
• Coarse screen: 0.35-0.50 mm holes, accepts to the main process line, rejects cascade to secondary screen for fiber recovery
• Secondary screen: 0.25-0.35 mm holes, accepts return to coarse screen feed, rejects to effluent

The reject handling system is critical for corrugated mills — each percentage point of fiber sent to the reject stream represents approximately -12 per ton in lost raw material (at 0-120/ton OCC cost). A well-tuned secondary screening system recovering 40-50% of primary screen rejects as accepts reduces total fiber loss to 1.5-2.5% of incoming furnish.

Fractionation and Refining Strategy for Corrugated Grades

Fractionation separates OCC pulp into long-fiber and short-fiber fractions, enabling targeted refining that maximizes strength while minimizing energy. Long fibers provide tear strength and ring crush, while short fibers contribute to smoothness and formation:

• Fractionation screen: 0.15-0.20 mm slots, long-fiber fraction (30-40% of total) sent to disc refiner for intensive treatment
• Long-fiber refining: 660 mm double disc refiner at SEL 2.0-2.5 J/m, target CSF drop 80-120 mL
• Short-fiber fraction: bypasses refining or receives light post-refining at SEL 0.8-1.2 J/m

Fractionation-based refining reduces total refining energy by 25-30% compared to whole-stock refining because only 30-40% of the fibers undergo high-intensity treatment. For a 400 TPD corrugated medium machine, annual energy savings from fractionation range from 5,000 to 5,000.

Equipment Maintenance in High-Contamination Environments

• Drum pulper screening plates: inspect weekly for hole enlargement from abrasive wear, replace at 4,000-5,000 hours
• HD cleaner cones: ceramic-lined lower cones last 8,000+ hours vs 3,000 hours for polyurethane — invest in ceramic for long-term cost reduction
• Screen rotors: check foil-to-basket clearance every 1,000 hours, adjust to maintain 1.5-2.5 mm gap for optimal pulse cleaning
• Reject conveyor magnets: clean daily to prevent tramp metal from reaching screen baskets downstream

OCC recycling is a demanding application that requires robust equipment design and disciplined maintenance practices. Leizhan Technology provides complete OCC recycling systems engineered for high availability in continuous operation environments.

Contact: leizhanequipment@gmail.com | www.pulprefining.com