JAPAN TAPPI JOURNALVol. 57, No.7
July 2003 Abstracts
Oxidation of Carbohydrate and Lignin During ECF Bleaching Process
Yuji Matsumoto
Wood Chemistry Laboratory, Department of Biomaterial Sciences,
Graduate School of Agricultural and Life Sciences, The University of Tokyo
The dependency of carbohydrate degradation on the oxidation of lignin during
ECF bleaching is reviewed based on the results mainly obtained
in Wood Chemistry Laboratory, The University of Tokyo.
The progress of lignin oxidation during oxygen bleaching can be separated
into three clearly distinguished phases. Oxidation of the first
phase is mainly due to the direct reaction of molecular oxygen
with phenilic unit in lignin. During the second and third phases,
oxidation of lignin occurred mainly due to the active oxygen species.
Those active oxygen species are also present in the first phase
but probably reduced by the reaction with phenolic groups in lignin.
However, those active oxygen species could attack carbohydrates
as well as lignin. Since the active oxygen species are produced
by the reaction of oxygen with lignin, the oxidation of carbohydrates
during oxygen bleaching process can be regarded as "co-oxidation" phenomena.
The effect of metal ion on the formation of those active oxygen
species and the reaction selectivity of active oxygen species to
react with lignin and carbohydrates were studied by various model
experiments. The formation of active oxygen species and the effect
of metal ion, and, co-oxidation of carbohydrate and lignin during
ozone bleaching are also briefly discussed.
Key Words : Oxygen, Hydrogen Peroxide, Ozone, Lignin, Carbohydrate, Oxidation
Ozone Bleaching and AHL-Stage Acid Treatment in a Modern Multichemical Bleach Plant
Fukuzawa Tamio
Andritz K.K., Japan
Pikka Olavi and Vehmaa Janne
Andritz Oy, Kotka, Finland
From a chemical point of view, there are many alternatives for pulp bleaching
today. The ozone stage, Ahl-stage and combinations of these with
the D-stage give plenty of possibilities for processes and set
a new standard for low chemical consumption.
Part of the kappa number is generated by hexenuronic acid groups bound in
xylan. When determining the kappa number, the hexenuronic acid
(HexA) groups are also titrated. Included in the kappa number determination
is hence the total amount of the lignin and HexA contained in the
pulp ? not only the amount of lignin. Except for oxygen and peroxide,
all present bleaching chemicals react with the hexenuronic acid
group. This leads to an increase in the consumption of these bleaching
chemicals. /1/.
Ozone is a strong bleaching chemical which has been closely connected with
the production of TCF pulp. When the demand of TCF pulp decreased,
ozone stages were also used in ECF sequences and the results of
these ozone ECF sequences have made ozone an extremely attractive
choice for modern ECF sequences.
A Theoretical Basis for the Hot Chlorine Dioxide Bleaching Process and Mill Results from the First Installation
Martin Ragnar
Kvaerner Pulping AB, Fiberline Division, R&D
Hot chlorine dioxide bleaching is rapidly evolving to become the standard
choice for the first bleaching stage in an ECF sequence for HW
kraft pulp. In this article data from experiments on a large number
of different HW species are presented with respect to their bleachability
in a D*ED (D* here denotes hot chlorine dioxide bleaching) sequence
compared to in a DED sequence. Results from the operation of the
first mill installation of hot chlorine dioxide bleaching are compared
and found to agree well with the laboratory results. Finally hot
chlorine dioxide bleaching is compared with hot acid treatment
followed by chlorine dioxide bleaching, (AD)* technology. In addition
a 2-stage bleaching sequence including hot chlorine dioxide bleaching,
(DQ)*(PO) is included in the comparison of e.g. strength properties
and bleaching chemical costs. It is concluded that the 2-stage
sequence shows a lot of benefits compared to the other sequences
and that this is even more true in a Japanese context.
Keywords：hardwood, Eucalyptus, ECF bleaching, chlorine dioxide, hydrogen peroxide, hot acid treatment, hot chlorine dioxide bleaching, hexenuronic acid, brightness reversion
Beneficial Improvement of Environmental Impacts by Elemental Chlorine-free Bleaching－Model Experiments and Mill Experience－
Hiroshi Ohi
Institute of Agricultural and Forest Engineering, University of Tsukuba
Keiichi Nakamata
Technical and Development Division, Hokuetsu Paper Mills, LTD.
Kraft pulp and sulfite pulp bleaching mills using chlorine, chlorine dioxide
(D) and other chlorinated compounds are under surveillance of the
dioxins regulation in Japan. One of questions is whether water
qualities of process sewers in chlorine dioxide bleaching (Elemental
Chlorine-free bleaching: ECF bleaching) mills are less than the
environmental water quality (1pg-TEQ/L) or not. Objectives of this
report are to review studies about the dioxins level of ECF mill
sewers and model experiments from an aspect of the environmental
water quality. Laboratory bleaching were carried out using a mill
hardwood oxygen-bleached kraft pulp (LOKP), chlorine dioxide from
a mill R8 generator in a laboratory high-share mixer. Active chlorine
factors were in the range of 0.14-1.14. In all cases, 2,3,7,8-TeCDD
and TeCDF were not detected for the pulps and spent liquors. Examination
of process water from an ECF bleaching line in Niigata mill of
Hokuetsu Paper Mills, LTD. shows that the concentrations of the
dioxins in both sewers of the chlorine dioxide stage (D0) and the
alkali stage (E/O) were below 1 pg-TEQ /L, and that the 2,3,7,8-tetrachlorodibenzofuran
(TCDF) concentrations were 0.41 pg/L or less. In addition, a main
source of 1,3,6,8- and 1,3,7,9-tetrachlorodibenzo-p-dioxins in
the process water seemed to be an agrochemical in water supplied
from a river.
In the meantime, Japan revised the Air Pollution Control Law in 1996. The
main purpose of the law is to reduce discharge of toxic pollutants
such as carcinogenic substances into the air. The Japan Papermaking
Association estimated the nationwide chloroform discharge to air
for the fiscal year 1996 at 1655 t on the basis of field studies,
and initiated a reduction of the discharge. As a result, the estimated
discharge was reduced to 1118 t, which was a reduction of 32%,
for the fiscal year 1999. However, further reduction is required
because there is still much discharge. We estimated chloroform
formation and discharge in the mill having an ECF bleaching line
and a chlorine bleaching line as well as an effluent treatment
process. It was clarified that the chloroform formation in ECF
bleaching was approximately one eightieth of that in chlorine bleaching.
Keywords : Dioxins, Chloroform, Pulp bleaching, Chlorine dioxide, Agrochemical
The Situation of the Technology for the Reduction of COD from
the Bleach Plant
Lennart Meuller and Lillemor Holtinger
Eka Chemicals AB, S-445 80 Bohus, Sweden
Muneo Sakamoto
Nissan-Eka Chemicals Co.,
This presentation will deal about technologies for the reduction of COD from
the bleach plant, mainly focused on the partial closure system,
and also referred to the closed cycle of the bleach plant.
Based on laboratory evaluations of partial closure when applied
to the ECF bleaching of conventional and oxygen delignified eucalyptus
kraft pulps, the following conclusions can be made:
. about 50% of the bleach plant COD, BOD and color will be returned
to the recovery system.
. less than 20% of Ba, Ca, Fe, Mg, and Mn and about 35% of the oxalate will be recirculated.
. only about 5% of the total chloride will be returned.
. the eucalyptus effluents are easy to treat with obtainable AOX and COD reductions of
about 80% and 70% respectively.
Ultrafiltration and partial closure of alkaline filtrates in ECF bleaching can reduce final bleach plant effluent COD by as much as 60% and AOX by as much as 40%.
Ultrafiltration of ECF alkaline filtrates can be achieved with
both high fluxes and little fouling using commercially available
membranes.
Experience in full scale from a pulp mill shows that partial
closure of the bleach plant is possible, while retaining the ECF
concept.
Based on a reduction of the total emission from the mill a more effective
biological treatment should be considered.
Results from pilot plant work shows that the ECM system is able to transform
the bleach plant effluent to clean condensate, a methanol containing
condensate, carbon dioxide exhaust gases and a mixed solution of
sodium salt and heavy metals in a sludge.
Keywords; Bleaching, ECF, TCF, softwood, eucalyptus, COD, AOX, Effluent characterization, Partial closure system, Total closure system
Operating Experience of ECF bleaching with Xylanase Treatment
Takashi Oishi
Oji Paper Co. Ltd., Yonago Mill
Yonago mill of Oji Paper produces approximately 1,200 tons of hardwood pulps
per day at 85-86% ISO brightness for coated paper products.
Xylanase treatment with on-site enzyme production was introduced into the
hardwood kraft pulp bleaching process (C-E/O-dnD ) in October 1998.
A thermostable xylanase from a microorganism ,Bacillus sp. S-2113,
that we isolated through screening was selected for use in this
process. The xylanase-containing culture was applied to the bleaching
process without removing the bacterial cells from the culture medium.
Therefore, xylanase treatment process could be operated economically.
Introducing xylanase treatment was allowed to reduce bleaching
chemicals, so chemical cost was lower than before.
In November 2000, the bleaching process was converted to ECF one( D0-E/O-dnD).
As a result，effluent AOX and chloroform emissions have decreased
significantly. It is recognized that introducing xylanase treatment
is allowed to reduce bleaching chemicals in ECF bleaching process,
too.
Operating Condition of Ozone ECF Bleaching
Takao Suzuki
Yufutsu Mill, Nippon Paper Industries Co., Ltd.
Medium consistency ozone bleaching plant was started up at Yufutsu mill in
January 2001. This is the first plant that uses ozone gas as a
bleaching sequence in Japan. By changing conventional C/D-E/op-D
into ZD-E/op-D, we have entirely excluded the usage of elemental
chlorine.
The bleached pulp with ozone is converted continuously to be paper products
without any kinds of faults. The main cost of ozone generation
is electricity expense, and then the important factor to introduce
ozone bleaching is a possibility to supply inexpensive electricity
by private-generation system. In this case, the total cost of the
ozone ECF bleaching is as low as that of chlorine bleaching, and
furthermore less than that of chlorine dioxide ECF bleaching.
Conclusively the introduction of this bleaching system has made satisfactory
results as expected for bleaching effectiveness, chemical costs,
and environmental impacts, in spite of the frequent initial troubles
of the ozone generator and scaling on the facilities.
Operating Experience of Improved ECF Bleaching Sequence
Shinichi Hara
Hachinohe Mill, Mitsubishi Paper Mills Limited
ECF bleaching has superseded the conventional chlorine bleaching on NO.3 LBKP-production
line in Hachinohe mill of Mitsubishi Paper Mills limited in 2000.
The operational data of ECF bleaching for two years made it obvious
that the brightness of oxygen-bleached pulp had larger influence
on the bleaching efficiency of ECF bleaching than kappa number
in contrast with the case of conventional chlorine bleaching. Furthermore,
it was shown that the improved ECF bleaching sequence had enabled
to reduce the chemical consumption and the scale trouble which
were main problems in ECF bleaching.
Scale Formation and Inhibition in ECF Bleaching Plant
Kenji Kowata
Pulp & Paper Industry Department, Kurita Water Industries Ltd.
Scaling troubles of calcium oxalate are observed frequently in ECF (elemental
chlorine free) bleaching process at a kraft pulp plant. Phenomena
of the scale formation is very complicated which includes simultaneous
nucleation, dissolution, growth and/or adhesion of crystals. The
scale formation tendency can be predicted by a saturation index
(SI) calculated by pH and concentration of scaling species.
Scale inhibitor shows effects such as nucleation prevention, crystal distortion
and suspended solid dispersion. For scale inhibitor treatment,
a critical saturation index (CSI) is defined as a maximum SI which
shows no nucleation at some inhibitor concentration.
ECF bleaching process has a tendency to show higher SI compared with a conventional
bleaching. At a washing filter of chlorine dioxide stage in ECF
process, CSI optimized "Depoclean" treatment shows a
stable operation without scaling trouble.
Elemental Chlorine Free Bleaching Impact on Metal Management
Joe Konopa
Pulping & Bleaching, Ondeo Nalco Corporation
With the implementation of the Cluster Rule in the United States, all bleached
grade kraft pulpmills were required to meet stringent levels of
absorbable organic halides in the effluent. The method most mills
used to meet the absorbable organic halide levels was to convert
to 100% substitution of chlorine dioxide in the predominately C
or CD first stage. As mills substituted chlorine dioxide in the
first stage of the bleachplant, thereby converting to elemental
chlorine free (ECF) bleaching, several key parameters were impacted.
Two of these were that delignification in ECF was less than partial
substitution of chlorine dioxide in the chlorine stage and secondly
the increase in pH in the first stage did not give the same level
of metals solubility as compared to chlorine or CD bleaching. Metals
management has become a significant issue in ECF bleaching as metals
that previously had a minor influence in bleaching now create issues
with inorganic deposition and efficiency reduction of peroxide
bleaching. Several operating conditions have been identified that
when optimized, reduced the issues associated with scale development
in various stages of the bleachplant.
Keywords : elemental chlorine free, ECF, scale, metal management, Scale Rate Monitor
How to control scale deposit problems in ECF bleach plant
Hirotaka Tanabe
Yokkaichi laboratory, Hakuto Co., Ltd.
Because of environmental concerns about chlorinated organic compounds and
chloroform in kraft mill effluent, new technologies of kraft pulp
bleaching was studied and come into practical use.
New ways of bleaching are ECF and TCF bleaching. ECF bleaching does not use
both elemental chlorine and hypochlorite, and TCF bleaching does
not use chlorine compound at all. In Japan, converting to ECF bleaching
is general.
Basically, scale deposit problems often occur in beaching plant. Along with
the conversion to ECF bleaching, the tendency of scale deposit
formation greatly changes.
In this report, we show characteristics and control methods of scale deposit
in ECF bleaching.
IGT’s New Testing Machine
Toshimichi Hashimoto
IGT testing Systems, Japan branch
IGT’s new Testing machine, Global Standard Tester (GST) Series has been introduced
in Japan.
On of the features of this machine is high reproducibility test result, simple
operation and short testing time.
IGT has much knowledge and technology on printability test equipment, which
was accumulated during more than 60 years, since its establishment
in 1939 in Amsterdam.
Since 1939, many of our Testing Machines have kept the basic principle, this
proves the high level of basic design of these machines.
We are convinced that our IGT Testers are quite mature since our R+D engineers,
having large knowledge on printability testing, printability testers
and machine engineering have worked a long time in development
and modification for improvement of these machines to reach an
optimised design and high performance.
The present technology is not the same as the one in 1939 any longer.
Our end users needs are also changing accordingly. It is time to carry out
the test on our new testing machines to meet present demand of
accuracy, speed and repeatability.
You can feel our 60 year long history and experience; accumulated knowledge
and technology when using our newest testing machines of the Global
Standard Tester series.
Manufacturing of Magnetic Papermaking Pulp and Paper(Part Ⅳ)－Micropore-Loading of Magnetite in the Cell Wall－
Fujiwara Katsuhisa
Paper Industrial Research Institute of Ehime Prefecture
Distribution of magnetite components present in magnetic pulps, which were
prepared by in situ synthesis according to the previously reported
method, was studied. Transmission electron microscopic (TEM) observations
and electron diffraction analysis combined with TEM revealed that
highly crystalline magnetite particles were present in the magnetic
pulps. Mapping analysis of the magnetic pulp using iron of magnetite
as a marker element was then carried out by means of an energy-dispersive
X-ray analyzer attached with TEM. The obtained results showed that
magnetite was formed in micropores in cell walls of the magnetic
pulps. Also in the case of magnetic pulps prepared by in situ synthesis
of manganese-ferrite, zinc-ferrite and manganese-zinc-ferrite,
it was indicated that these ferrite components were present in
micropores in cell walls.
Keywords: Micropore, Cell wall, in situ synthesis, Magnetite, Ferrite, Filler, Micropore-loading, Magnetic pulp, Never-dried fiber, Loading
The Evaluation of Paper Sludge (PS) for Zeolite synthesis(Part
1)
-Optimal Mineral and Chemical Composition Range for Zeolite Synthesis-
Takao Ando, Masato Saito, Shigeo Muramatsu and Kimio Hiyoshi
Fuji industrial research institute of Shizuoka prefecture
Junsuke Haruna, Naoto Matsue and Teruo Henmi
Department of agriculture, Ehime Univ.
Paper sludge (PS) discharged from the paper mills in Fuji city, Shizuoka prefecture
reach about 1,018,000 tons/year. The development of the zeolite
synthesis technique is essential from the viewpoint of recycling
of wasting materials.
Generally, PS ash contains not only Si and Al, but also significant amount
of Ca. From our previous study on the interaction between Ca in
calcite and Si as well as Al in kaolinite during the zeolite synthesis10),
the following results became clear. (1) The metakaolinite that
was heated at 600℃ is converted to zeolite by the alkaline (NaOH)
hot water treatment at 100 ℃ for 4 hours. (2) Co-existing Ca is
expected to inhibit the formation of zeolite, since the amorphous
Ca-silicate hydrate will form preferentially and Si-O-Al bonds
will not. (3) Chemical and mineralogical characterization of the
zeolite synthesized by the mixture of Ca(OH)2 and metakaolinite
led us the supposition that the chemical formula of the amorphous
Ca-silicate hydrate was Ca3Al2(SiO4)3X(OH)4X. From these results,
we cleared the conversion rate of LTA (Linde Type A)19),20) zeolite,
and the ideal mineralogical composition range of PS for the zeolite
synthesis was obtained.
In this study, the practical PS ashes were mineralogical and chemical characterized
and their possibility as starting materials for the zeolite synthesis,
was examined. The 20 PS ashes from paper mills in Fuji city were
heated at 600℃ for 12 hours and a X-ray fuluorescence (XRF) measurements
were tested.
The talc, kaolinite, calcite constitution ratios of them were determined by
the normative method from a X-ray diffraction (XRD) profiles obtained,
and were compared with the above ideal composition range. It was
found that 50％ of the PS ashes could be directly used for the zeolite
synthesis and the others could by addition of Si compounds.
Keywords: zeolite, paper sludge, calcite, talc, kaolinite
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