Learn about the manufacturing process about the paper industry namely the pulping, recovery, bleaching and finishing processes.

1. Paper Industy
The manufacturing process

2. Pulping process
Wood chips are cooked in pressurized
digesters with strong basic solution and
high temperature
Deliginification of wood chips gives
cellulose pulp that are free from lignins

3. Some chemicals used in Kraft’s process includes
❖Caustic Soda
❖Sodium Sulfide
❖Sodium Sulfate
Pulping process

4. Recovery process
Black liquor formed as a byproduct of
pulping, containing excess pulping
chemicals that can be reused
This process encourages 97% chemical
efficiency for Kraft’s chemical pulping
process

5. Some chemicals used include
❖Soda Ash
❖Lime or Hydrated Lime
Recovery process

6. Bleaching process
Wood pulp retain their brownish parent color
if untreated
This is due to residual ligins still present in
the pulp
Bleaching usually involves using chemicals
with strong reacting properties to whiten
the pulps

7. Some chemicals used include
❖Sodium Hypochlorite
❖Sodium Chlorite
❖Sodium Thiosulphate (anti-chlor agent)
❖Hydrogen Peroxide
Bleaching process

8. Finishing Process
Additives are added in this process to
modify the physical properties of paper
Some properties includes opacity, optical
brightness, strength and density of the
final paper product

9. Some chemicals used include
❖Calcium Carbonate
❖Titanium Dioxide
❖Talc
Finishing Process