Idaho Forests and Clearwater Paper Mill

Importance of Idaho Forests

• Idaho forests contribute significantly to the paper industry.
• Clearwater Paper in Lewiston, Idaho uses wood chips, sawdust, bark, and other small pieces for paper and electricity.

Clearwater Paper Mill

• Clearwater Paper is the second largest customer for many area sawmills.
• The mill accounts for half of all forest product sales in Idaho.
• Processes over 240 truckloads of wood fiber daily from Idaho sawmills.

Process of Making Paper and Energy

Wood Fiber Processing

• Truck Unloading: Trucks are raised to an 80° angle to empty contents.
• Sorting: Wood chips and sawdust are used to manufacture pulp; bark and small pieces (hog fuel) generate steam and electricity.

Pulp Manufacturing

• Screening: Wood chips are screened; inappropriate sizes are returned to hog fuel pile.
• Digestor Process:
  • Chips contain ~50% water, 25% cellulose fiber (needed for pulp), and 25% lignan (natural glue).
  • Digestors (pressure cookers) separate lignan using white liquor (cooking chemicals).
  • Heat and pressure dissolve lignan, breaking down wood chips.
  • Resulting cooking liquid with dissolved lignan is called black liquor.

Recovery Process

• Evaporation: Water removed from black liquor, concentrating lignan and chemicals.
• Burning: Concentrated mixture burned in recovery boiler to generate steam and electricity.
• Chemical Recycling:
  • Remaining chemicals form green liquor.
  • Lime added to recycle into white liquor, completing the cycle.
  • Craft process makes paper cheap and environmentally sound.

Bleaching

• Pulp washed with bleach and water to remove residual lignan.
• Results in bright white fiber ready for use.

Water Usage

• Role of Water:
  • Used extensively for cooling, cleaning, and moving products.
  • Essential in boilers for steam and in cooling machinery.
• Recycling:
  • Water is recycled and returned to the river after purification.
  • The mill operates with strict discharge constraints.

Environmental Stewardship

• Modern pulp mills maintain high environmental standards.
• Equipment investments assure minimal waste and environmental impact.
• Emphasis on being good environmental stewards.