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De-inking is the process of removing printing ink from
waste paper so that the waste paper may be recycled. The process consists of
passing pulped waste paper through a series of punched screens, slot screens,
and centrifugal purifiers to mechanically separate all non-paper components such
as staples and thick adhesive layers. These components should be dimensioned and
mechanically stable so they remain as large particles. Once the non-paper
components are removed, the pulp goes into a de-inking tank. Through a process
known as flotation, the ink separates from the paper fibres and gathers
on the surface of air bubbles. These loaded air bubbles float to the surface of
the flotation cell, forming a dark foam containing printing ink, fragments of
paper fibre, fillers, and coating pigments. Once this foam is removed, the pulp
can be handled and manufactured in the same manner as pulp from virgin fibre. In
some cases, the de-inked pulp is bleached to brighten it, but not always.
In Newfoundland and Labrador, the pulp and paper
industry is currently facing a shortage of available fibre. In addition, both
the pulp and paper industry and the sawmilling industry are looking to expand
production. The Province is firm in its commitment to sustainable forestry and
as part of its resolve, it has encouraged the use of alternative sources of
fibre to offset this supply deficit. One potential alternative source of fibre
for the pulp and paper industry is de-inked/recycled waste paper. The use of
this type of pulp would provide additional fibre to pulp and paper mills and at
the same time free up timber for use in sawmills.
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