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 �W)−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