Coating Board Paper Making Line: Pulp to Coated Sheet Production Solutions

Coating Board Production Fundamentals

Coating board, also known as coated duplex board or white back board, is a multi-layer paperboard product widely used for packaging of consumer goods, pharmaceuticals, and food products. The production line requires specialized stock preparation for multiple furnish layers: a white top layer (bleached chemical pulp), middle filler layers (recycled fiber or mechanical pulp), and a back layer (unbleached or recycled fiber). Typical basis weights range from 200-450 gsm with production speeds of 150-400 m/min.

Multi-Furnish Pulping System

Coating board production demands separate pulping lines for each layer furnish. The top layer pulper typically processes bleached kraft pulp at 4-5% consistency with 132-250 kW motor power. The filler and back layer pulper handles mixed waste paper and OCC at 200-500 TPD capacity. Each pulping line includes dedicated D-type Hydraulic Pulpers with extraction plates sized for the specific fiber type. Raggers and junkers remove contraries such as baling wire and plastic film at the pulping stage.

Layer-Specific Screening and Cleaning

Top layer stock passes through fine Pressure Screens with 0.12-0.18mm slots to achieve the spotless surface required for coating. Filler layer screening uses 0.20-0.30mm slots, balancing cleanliness with yield. Each layer is processed through dedicated screening and cleaning lines to prevent cross-contamination. High-density cleaners protect the screens from heavy debris, while forward cleaners remove lightweight contaminants. Reject rates are maintained at 10-15% with fiber recovery exceeding 95% across all layers.

Refining Strategy for Multi-Layer Formation

Each layer requires distinct refining treatment. Top layer refining targets 70-90 kWh per ton with the Double Disc Refiner, using fine bar patterns to develop surface smoothness without reducing opacity. Filler layer refining is minimized at 40-60 kWh per ton to preserve bulk and stiffness. The 910mm disc refiner with 400-500 kW motor covers most coating board production scales. Hydraulic gap adjustment maintains consistent refining intensity as plate wear progresses.

Energy and Cost Management

Total stock preparation energy for coating board lines runs 130-200 kWh per ton, with pulping consuming 15-25 kWh, screening 8-12 kWh, and refining accounting for 60-120 kWh per ton. The multi-layer approach allows optimization of fiber cost: high-cost bleached fiber is used only in the thin top layer (20-30 gsm), while lower-cost recycled fiber fills the middle and back layers. Steam consumption for the drying section averages 1.8-2.2 tons of steam per ton of paper at the paper machine.

Maintenance Planning for Multi-Line Operations

Operating multiple parallel stock preparation lines requires coordinated maintenance scheduling. Pulper extraction plates should be inspected monthly and rotated at each inspection to ensure even wear. Screen basket service life for top layer (fine slots) averages 12-15 months, while filler layer baskets (wider slots) last 18-24 months. Refiner plate changes are staggered across layers to avoid simultaneous downtime on all lines. A recommended spare parts inventory includes one complete set of pulper wear parts, two screen baskets per line, and one refiner plate set per refiner.

Integrated Turnkey Solutions

Leizhan Technology provides complete coating board production line engineering, from raw material handling through the paper machine and coating station. Process design considers the specific requirements of each layer while optimizing overall material and energy efficiency.

Contact for project consultation and equipment proposal:
Email: leizhanzhang@gmail.com
Website: www.pulprefining.com