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The aim of this paper is to describe some of the difficulties encountered when recycling in
deinking plants in order to produce high-quality white deinked pulp (DIP). The deinking process
requires, after reslushing recovered papers, an optimal size of ink particles. This size depends on
the recycling techniques, but mainly on the nature of the ink.
Firstly, some data will be presented regarding the importance of recycled fibres as fibre source
for the paper industry. The techniques used for recycling recovered papers and the deinking
process will be described. The main difficulties related to deinked pulp will be presented and two
of them described in detail.
For waterbased ink printed paper, the ink is dispersed into small particles during the conventional
alkaline recycling process and are not removed by flotation, the final brightness of the DIP is
insufficient.
Varnished printed papers lead to large ink particles insufficiently removed during the recycling
process, some of these particles remain in the final pulp and are visible to the naked eye. These
remaining particles are called specks.
Environmentally friendly printing materials (for recycling) should meet the requirements for water
and alkali resistance and lead, after reslushing, to particles in an optimum size range for removal.