ISSN 1070-4272, Russian Journal of Applied Chemistry, 2017, Vol. 90, No. 3, pp. 440−445. © Pleiades Publishing, Ltd., 2017.
Original Russian Text © F.Kh. Khakimova, R.R. Khakimov, O.A. Noskova,
2017, published in Zhurnal Prikladnoi Khimii, 2017, Vol. 90, No. 3, pp. 380−386.
AND POLYMERIC MATERIALS
Pulp Depitching in the Bisulﬁ te Pulping Step
F. Kh. Khakimova*, R. R. Khakimov, and O. A. Noskova
Perm National Research Polytechnic University, Komsomolʼskii pr. 29, Perm, 614990 Russia
Received February 6, 2017
Abstract—OS-20 nonionic surfactant produced in Russia was used as a depitching additive in bisulﬁ te pulping.
OS-20 ensures efﬁ cient depitching of bisulﬁ te pulp produced from various kinds of wood (spruce, aspen, birch
wood or their blends). The strongest decrease in the total and “harmful” pitch content in pulping in the presence
of the surfactant was reached for spruce and aspen wood and for the blend of spruce and birch wood.
Pitch gives rise to serious problems in the production
of pulp and paper. In particular, pitch deposits on the
equipment are formed. Today this problem has become
more acute because of the shortage of the wood raw
material, so that it becomes impossible to keep the
wood for a long time in air to reduce the manifestation
of the pitch troubles. Furthermore, today pulp-and-
paper enterprises use to increasing extent hardwood
characterized by higher, compared to softwood, content
of difﬁ cultly soluble pitch components: fats and
unsaponiﬁ able substances . Therefore, reducing the
pitch content of the pulp is an urgent problem of the
Management of “pitch troubles” is complicated by
the fact that they arise in different steps of pulp and
paper processing, up to paper-making and press-pate
The pulp depitching in different steps of the process
at a number of enterprises in Russia is performed using
depitching agents, mainly imported, or compounds
based on mixtures of surfactants, which makes such
depitching procedures very expensive.
Pitch troubles are the most pronounced for sulﬁ te,
bisulﬁ te, and sulfate hardwood pulp . The pulping is
the potential site of appearance of “harmful” pitch in the
The total and “harmful” pitch content of the pulp can
be distinguished. The total pitch content is signiﬁ cant
for the industry only because it determines the
“harmful” pitch content, giving rise to pitch troubles. A
characteristic feature of “harmful” pitch is its stickiness
and capability for aggregation to form coarse particles
, despite the fact that none of the pitch components
taken separately exhibits such properties. The “harmful”
pitch is formed when certain pitch components,
separated from each other in the initial wood, are mixed
together. Pulping is the ﬁ rst process in which this mixing
becomes possible .
A widely used way to eliminate pitch troubles is
using surfactants in various steps of pulp and paper
production. However, it is probably most appropriate to
use surfactants in pulping, i.e., in the process in which
the prerequisites for pitch troubles are mainly created,
especially in the ﬁ rst step of pulping (impregnation
of wood chips with sulﬁ te pulping acid) and ﬁ rst step
of standing. In this process, the pitch extracted from
wood forms a colloidal dispersion in the pulping liquor.
Therefore, it is appropriate to introduce surfactants
into the pulping solution prior to pulping in laboratory
experiments and to feed them into the pulping digester
simultaneously with feeding the pulping acid [4, 5] in
the industrial process.
This study is aimed at determining the conditions of
the depitching of pulp from different kinds of wood by
introducing a surfactant produced in Russia in the sulﬁ te