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Semiannual Conferences Review: July-December 1994 Semiannual Conferences Review
July December 1994
John K. Borchardt, Gary M. Scott
1.0 INTRODUCTION
The second half of 1994 was relatively quiet
and Mahendra R. Doshi
2.0 WHATS NEW
with
respect to conferences. As indicated in Table 1, only
58 papers related to recycling were presented at
the five conferences reviewed here. Note that only
abstracts were available for the 208th National
Meeting of the ACS held in Washington, D.C. The
International Pan Pacific Conference and AIChE
Meeting were held at the same time and same place
as the TAPPI Pulping Conference, in San Diego.
Papers for the AIChE meeting were not available
in the proceedings but copies were distributed at
the meeting. AIChE proceedings will be published
within a year subsequent to the peer review pro-
cess.
Pulp & Paper International organized a meeting,
the PPI First International Conference & Exhibi-
tion on Paper & Board Recycling, on Nov. 8-10,
1994, in London, UK. We plan to have more details
and a review of that conference in an upcoming is-
sue of PPR. The Institute of Paper Science and
Technology (IPST) and TAPPI organized a confer-
ence, Fundamentals and Practical Applications of
Paper Physics, on August 28-31, 1994, in Atlanta,
GA. Only abstracts of the papers were available.
Due to time constraints, we could not include the
conference in this review but will try to include it
in a future issue.
Borchardt is Research Manager, Pulp & Paper Surfac-
tants, Shell Chemical Company, Westhollow Technical
Center, P. O. Box 1380, Houston, TX 77251-1380, USA.
Scott is Research Chemical Engineer, USDA, Forest Ser-
vice, Forest Products
Laboratory, One
Gifford Pinchot Dr.,
Madison, WI 53705-2398, USA. Doshi is President, Doshi
& Associates, Inc., 18 Woodbury Ct., Appleton, WI 54915,
USA.
Progress in Paper Recycling / February 1995
Like all previous conferences, papers presented at
the conferences reviewed here contain both funda-
mental and practical information to satisfy the
needs of practitioners as well as academicians. Pa-
pers of a practical nature included mill experiences
at Weyerhaeusers OCC plant in Springfield, Or-
egon (P-2), a newsprint deinking plant at Bear Is-
land Paper Co., Ashland, Virginia (P-20), and an
office paper deinking plant at the James River Mill
in Halsey, Oregon (A-4). At the other end of the
spectrum, there were papers dealing with flotation
deinking under very idealized conditions (P-17, C-
5, and A-7).
Topics receiving greater attention at the conferences
covered included:
Global deinking perspective (P-14, A-2, C-4, and
I-l).
Quantification of contaminants (P-7, P-8, P-12,
and P-11).
ONP/OMG deinking (P-15, P-16, P-17, P-18, P-
19, P-20, P-21, P-22, and C-3)
OWP deinking (A-4, A-5, A-6, A-7, P-25, P-26, P-
27, C-5, and C-6)
q
Residue utilization (A-1O, A-11, A-12, E-2 through
E-12)
Interesting similarities and differences in deinking
plant design, paper quality specifications, and wa-
ter usage in Europe, Japan, and North America are
discussed in Section 4.1. The need for a good method
for the quantification of contaminants was quite
evident from the discussion in Section 5.0. Progress
in flexo and OWP deinking is encouraging, as can
be discerned from Sections 4.1 and 4.2, respectively.
Papers presented at the TAPPI
ference point out the popularity
February 1995 Vol. 4, No. 2
Engineering Con-
and usefulness of
Page 89 Table 1. Conferences Reviewed.
Conference
Date
Code
Papers
Am. Chem. Soc.
August 21-25, 1994
A
12
TAPPI Eng. Conf.
Sept. 19-22, 1994
E
12
Int1 Pan Pacific Conf,
N
OV
. 6-9, 1994
I
1
TAPPI Pulping Conf.
N
OV
. 6-10, 1994
P
27
AIChE Meeting
Nov. 10, 1994
C
6
Total Papers
58
circulating fluidized bed technology for the incin-
other brown grades. Due to the rising cost of virgin
eration of mill residue,
An important contribution that stands out as a sig-
nificant achievement deals with the automation of
a laboratory screening procedure, discussed by
Bittner (P-8). The laboratory screening procedure
has been used for quite some time for the concen-
tration of contaminants. The development by
Bittner automates the screening step as well as the
step of collecting rejects from the screen. More work
is needed to identify stickies from the screen re-
jects.
Noteworthy projects conducted by Dorris and
Sayegh (P-25) at PAPRICAN and Johnson and Th-
ompson (P-26) at the University of Maine both in-
volve deinking of OWP. Dorris and Sayegh point
out the importance of apparent toner layer thick-
ness and toner density in deinking OWP. Papers
with a relatively thick layer of toner particles
(greater than about 6 microns) result in a specky
sheet after pulping and flotation deinking compared
to those with a relatively thin layer of toner par-
ticles (less than about 6 microns). Johnson and
Thompson use a combination of Bauer-McNett clas-
sification and image analysis to identify attached
and detached toner particles in pulp. Results show
that detached toner particles are easier to float com-
pared to toner particles still remaining attached to
the fibers. Further work at both institutions should
provide insight into the deinking of OWP.
3.0 OCC PROCESSING
Old corrugated containers (OCC) have traditionally
been processed to make linerboard, medium, and
fiber, especially in the Northwest, and customer
demands for recycled products, a larger number of
mills are looking toward OCC to provide a greater
portion of their furnish for the production of other
products. This increase in the amount of recycled
materials can have significant effects on the pulp-
ing and papermaking processes. These effects in-
clude an increase in the amounts of wax, stickies,
and other contaminants that must be dealt with,
changes in the wet-end chemistry of the process,
and changes in the pulp properties which affect the
resulting product properties. Mini-mills are a con-
cept that has developed from this increased use of
OCC.
3.1 Screening and Cleaning
Medium-density or fine forward centrifugal clean-
ers are commonly used before pressure screens to
protect the screen plates from excessive wear. Vitori,
King and Winkler (P-1O) discuss the effect of con-
sistency on pressure screen performance. Results
show that the screening efficiency is higher at 1.5%
consistency than at 0.8% consistency. Thus, me-
dium-density cleaners, which operate at high con-
sistency should be used before pressure screens for
the removal of abrasive contaminants.
3.2 Chemistry Considerations
The increased use of OCC and the ultimate goal of
water closure for many recycling mills has led to
the need to carefully consider the chemistry in all
steps of the process (P-l). A variety of chemicals
are commonly used in the reprocessing of OCC into
linerboard. These include chemicals that are added
for a variety of reasons:
Page 90
Progress in Paper Recycling / February 1995 q
sizing
q
strength
q
contaminant control
q
retention
drainage
microbiological control
q
foam control
fabric cleaning
Mini-mills and other mills with a high water re-
cycle rate need to carefully consider the chemicals
that are added to their process since there is a lim-
ited capacity for purging them from the system.
Precipitation and scaling are also a concern in these
operations as the closed nature of the operation
causes a rapid buildup of solids in the water. Non-
traditional technologies, such as crystallization,
evaporation, and reverse osmosis may need to be
employed in order to achieve the low-water-dis-
charge goals.
tensity, pH, press conditions, and basis weight (P-
3). They concluded that refining of OCC produced
pulps with greater compression strength at the cost
of significantly decreased freeness. As expected,
increasing the refining energy increased the
strength properties of OCC; however, no advantage
was found due to refining at lower intensity. Refin-
ing at higher pH reduced the compressive strength
characteristics while increased press loading im-
proved the compressive strength.
Caustic soaking is another approach for improving
strength properties of OCC. Freeland continues to
perform laboratory and mill trials to show the ben-
efits of caustic soaking (E-l). Metal ions or cat-
ionic species could reduce the benefit of caustic
soaking. Use of chelating a