Reference Manual

14−4
Figure 14-3. Chlorine Dioxide (ClO
2
) Filtrate Flow
Drawing is from TAPPI’s Making Pulp and
Paper Series and is used with permission.
Figure 14-4. Alkaline Filtrate Flow
Drawing is from TAPPI’s Making Pulp and
Paper Series and is used with permission.
chemical recovery plants. TCF sequences use
various combinations of oxygen-alkali chemistry,
hydrogen peroxide, and ozone. This process tends
to be more expensive, have lower brightness, and
is susceptible to strength loss problems.
Mechanical Pulping
This process dissolves most of the lignin in the
original wood. High-yield mechanical pulps cannot
be bleached the same way because they contain
too much lignin. Bleached or brightened
mechanical pulps will never receive the high
brightness like that of a chemical pulp. The