8 Past and Present Challenges of Japanese Pulp and Paper Industry JUNZO NAKANO Department of Forest Products, University of Tokyo, Bunkyo-Ku, Tokyo, Japan
The purpose of this paper is two-fold as indicated by its title; to review how the Japanese pulp and paper industry developed during the past 100 years and how this industry is now struggling to overcome environmental problems and resource shortages. Growth of pulp and paper industry The pulp-wood cost has been more than half of pulp making cost. Therefore, the availability of low cost pulp-wood has occupied the most important position in pulp and paper industry. This is a reason why the history of pulping technology was also the history overcoming the shortage of pulp-wood at each period of the growth. Table 1 shows the economical situation of pulp and paper industry in Japan. This figure is rather old statistics. Pulp and paper industry ranks 12th, and wood and wood products industry ranks 14th. Therefore total sales of both industries, so-called forest products industry ranks 7th. There are different opinions in Japan how to divide the growth stages including the changes of pulp raw material and pulping technology. For convenience, the growth during the past 100 years is divided into next five stages; First stage 1872~1930, Second stage 1931~1944, Third stage 1946~1955, Fourth stage 1956~ 1969 and Fifth stage 1970~present. First stage 1872~1930 Table 2 shows main items occurred in the First stage. It was about 100 years ago that the first machine made paper was produced in Japan, that is, in 1874. At that time, raw material was mainly cotton rag. The industry kept growing steadily ever since. Sulfite pulp was produced in 1889, ground wood in 1890 and kraft pulp in 1925· 171
CELLULOSE AND FIBER SCIENCE
Table 1. Economic situation of pulp a n d paper industry i n J a p a n (1972) Industry Transport, machine. & implement Electr. machine & implement Food Iron & Steel General machine & implement Chemical Fiber & Textile Non ferrous metals Metal products Ceramic PetroleumS. Coal P u l p & Paper Publication & Printing Wood & Wood products Others
Employee
Sales Order Dollars' %
Order Number
V.
2
1
29.70 13.3
3
844
10.0
2
26.41 11.8
1
1,179
14.0
3 4
24.29 10.8 21.10 9.4
5 7
718 488
8.5 5.8
5
19.78
8.8
2
889
10.6
6 7 8 9 10 11 12
19.39 8.8 10.85 4.8 9.56 4.3 9.51 4.2 8.33 3.7 7-61 3.4 7.61 3.4
8 4 15 6 9 19 13
439 736 194 499 415 38 242
5.2 8.7 2.3 5.9 4.9 0.5 2.9
13
5.37
2.4
10
318
3.8
14
5.20
2.3
12
248
2.9
19.11
8-6
Total
223.72 100.0
1.166
14.0
8.413
100.0
*t -.Billion, * 2 : 1 , 0 0 0
Table2 F i r s t stage(1872~1930) of the g r o w t h of J a p a n e s e pulp & p a p e r industry 1) 1872 Establishment of first paper company 2) 1874 Production of machine made paper 3) 1878 Production of rice straw pulp A) 1880 Foundation of J a p a n Paper A s s o c i a t i o n 5) 1889 Production of sulfite pulp 6) 1890 P r o d u c t i o n of groundwood 7) 1905 Use of electric power in paper mill 8) 1912 Publication of J a p a n e s e book *Paper Technology" 9) 1925 Production of kraft pulp
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Table 3 shows pulp raw m a t e r i a l and pulp production i n 1903· I t i s worth noting that wood pulp production was only 2 6 . 2 % of t o t a l pulp i n 1 9 0 3 · In the f i r s t h a l f of t h i s stage, Japanese engineer improved pulp and paper production a f t e r the model of imported technology under the guidance of foreign e n g i neers. However, i n the 1 9 2 0 ' s , the domestic and foreign technique were mastered enough and the s p i r i t of independence also appeared. Pulp-wood i n the f i r s t stage was mainly f i r , hemlock and spruce. Second stage 1951~1945 Table k summarizes main items i n the second stage. In 1 9 3 1 , f i r s t d i s s o l v i n g s u l f i t e pulp was produced by the use of three stage bleaching, that i s by c h l o r i n e , sodium hydroxide and hypochlorite sequence. This year was also of f i r s t use of c h l o r i n e i n pulp bleaching. Since then, pine and beech were used as new pulp-wood, and reed and chaffs were also used as the a d d i t i o n a l s u p p l i e s . In 1 9 3 8 , a l c o h o l production from s u l f i t e spent liquor started. I t can be s a i d that various t e c h n i c a l developments were r i s e n i n the second stage. Pulp production i n 1941 was 1 , 2 7 7 , 0 0 0 tons and maximum before the Second World War* There were b i g pulp and paper m i l l s not only i n Hokkaido, but also i n Korea and Sahalin. Therefore, pulp and paper industry got a b i g shock due to the end of the war. Pulp production was only about 2 0 0 , 0 0 0 tons i n 1 9 4 6 . Third stage 1 9 4 6 - 1 9 3 3 Table 5 shows the o u t l i n e of t h i s stage. In Third stage, a l o t of wood species v/ere used as pulp-wood; pine, l a r c h , sugi (Cryptomeria), cypress i n a d d i t i o n to f i r , hemlock and spruce. And i n the hardwood species, poplar, a l d e r , oak, l i m e , b i r c h and so on were used besides beech. F i r s t Kamyr continuous digester was operated i n 1952. Since then, t h i s type of digester has become main one i n k r a f t pulp production. In 1 9 5 3 , pulp production were 1 , 5 1 0 , 0 0 0 tons which were above the maximum before the Second World War. During t h i s stage, high y i e l d pulping process, s o - c a l l e d semichemic a l and cold soda processes were adopted, and prehydrol y s i s k r a f t pulping began i n 1 9 5 3 · Fourth stage 1 9 5 6 - 1 9 6 9 Table 6 shows the o u t l i n e of Fourth stage. In the l a t t e r of Third stage and the f i r s t of Fourth stage, pine was used as pulp-wood i n a great q u a n t i t y . However, due to the shortage and cost up of softwood, the industry must look for other woods i n the early 1 9 6 0 ' s . Thus, the pulp-wood shortage was overcome by using hardwoods, slender branches, s m a l l -
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Table 3 Pulp raw material a n d production in 1903 Production Pulp t/year 7o Mitsumata&Kozo (Japanese paper) Straw Rag Vvbod (groundwood) Wood (sulfite pulp} Imported Total
18330
23.5
16.380 15.990 10,920 9,516 6.864
21.0 20.5 14.0 12.2 8.8
7 8 . 0 0 0 100
Table 4 S e c o n d stage(1931-1945) of the g r o w t h of Japanese pulp & p a p e r industry 1) 1931 Production of dissolving sulfite pulp 2) 1936 Production of Mg-base sulfite pulp from b a g a s s e 3) 1938 P r o d u c t i o n of sulfite pulp from reed P r o d u c t i o n of straw pulp by chlorine p r o c e s s . 20 t/d Alcohol production from sulfite spent liquor 4) 1939 Production of dissolving sulfite pulp from pine 5) 1940 Production of dissolving sulfite pulp from beech P r o d u c t i o n of dissolving sulfite pulp from chaffs, 10t/d 6) 1942 P r o d u c t i o n of dissolving sulfite pulp for Bemberg nayon
Table 5 Third stage(1946~1955) of the growth of J a p a n e s e p u l p & paper industry 1) 1947 2) 1951
Foundation of J a p a n Tappi Production of high yield pulp by cold s o d a process 3) 1952 Production of bleached kraft pulp from hardwood Operation of Kamyr continuous digester (third i n the world) 4) 1953 Production of dissolving kraft pulp Production of dissolving sulfite pulp for acetate rayon Production of neutral sulfite chemical pulp Wood s p e c i e s Softwood: fir, hemlock, spruce, larch, sugi( Cryptomeria), J a p a n e a s e cypress Hardwood:beech, poplar, alder, oak, lime,birch
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s i z e d t r e e s , waste woods a t s a w m i l l s and so on. It i s c e r t a i n t h a t the change from softwood t o hardwood was p o s s i b l e as a r e s u l t o f c o n s i d e r a b l e improvement i n pulping technology. As shown i n T a b l e 7, the use o f hardwood r o s e above the use o f softwood i n 1 9 6 4 . In 1 9 6 4 , e x c l u s i v e c a r r i e r s were c o n s t r u c t e d f o r the purpose o f i m p o r t i n g c h i p s from o t h e r c o u n t r i e s . At f i r s t , they s a i l e d t o the N o r t h America, and then to A s i a n c o u n t r i e s , A u s t r a l i a and S o v i e t Union. As a r e s u l t , the p e r c e n t a g e s o f Japanese dependence on f o r e i g n pulp-wood jumped from 2 . 8 % (461 , 0 0 0 m^) i n 1965 t o 39./+% ( 1 4 , 0 5 2 , 0 0 0 m3) i n 1 9 7 4 . Such a development i s shown i n T a b l e 8 . T h i s t a b l e shows a l s o t h a t the r a t i o of purchased c h i p s c r o s s e d over a h a l f o f t o t a l pulp-wood i n 1 9 6 5 · T a b l e 9 shows the i m p o r t e d p u l p wood s t a t i s t i c s . Japan i s now m a i n l y i m p o r t i n g p u l p wood from N o r t h A m e r i c a . J u d g i n g from a p o i n t o f p u l p i n g t e c h n o l o g y , the p r o g r e s s i n the F o u r t h s t a g e was more v e r s a t i l e than t h a t i n the T h i r d s t a g e . In 1957, k r a f t pulp prod u c t i o n r o s e above the s u l f i t e p u l p p r o d u c t i o n , and f o d d e r y e a s t was produced from s u l f i t e spent l i q u o r . I t i s w o r t h n o t i n g t h a t hardwood k r a f t l i n e r was p r o duced i n 1959 and s y n t h e t i c paper was produced i n 1 9 6 6 . Both were produced f i r s t i n the w o r l d . F i f t h s t a g e 1 9 7 0 ~ p r e s e n t T h i s s t a g e concerns the p r e s e n t and f u t u r e problems. At p r e s e n t , the Japanese p u l p and paper i n d u s t r y i s s t r u g g l i n g t o overcome the f u t u r e s h o r t a g e s o f pulp-wood and e n v i r o n m e n t a l prob^ lems. These two problems w i l l be d i s c u s s e d i n the following parts. F u t u r e s h o r t a g e o f p u l p raw m a t e r i a l s As metioned p r e v i o u s l y , about 40% o f pulp-wood are i m p o r t e d from o t h e r c o u n t r i e s . At p r e s e n t , t h e r e a r e about 75 e x c l u s i v e c a r r i e r s i m p o r t i n g c h i p s . As a r e s u l t , a l o t o f wood s p e c i e s a r e used as pulp-wood, as shown i n T a b l e 1 0 . However, even w i t h the i n c r e a s e o f i m p o r t e d pulp-wood, the pulp-wood s h o r t a g e has become o b v i o u s . I n o t h e r words, the Japanese p u l p and paper i n d u s t r y i s no l o n g e r a s e l f - s u f f i c i e n t i n d u s t r y as i t used t o be. T a b l e 11 shows the newest e s t i m a t i o n o f s u p p l y and demand of p u l p and paper by M i n i s t r y o f I n t e r n a t i o n a l Trade and I n d u s t r y ( M I T I ) . Pulp p r o d u c t i o n w i l l r e c o v e r the l e v e l o f 1973 i n 1978 and paper p r o d u c t i o n w i l l r e c o v e r the l e v e l o f 1973 i n 1 9 7 7 · MITI e s t i m a t e s t h a t p u l p and paper p r o d u c t i o n i n 1 985 w i l l be 1 4 , 8 0 0 , 0 0 0 t o n s f o r p u l p and 2 9 , 0 0 0 , 0 0 0 t o n s f o r paper and paper b o a r d . I n o r d e r t o a c h i e v e the t a r g e t , the f o l l o w i n g t h r e e p o i n t s h o u l d be s o l v e d from
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Table 6 Fourth s t a g e d 9 5 6 - 1 9 6 9 ) of the g r o w t h of J a p a n e s e pulp & p a p e r industry 1) 1957
2) 1959
3) 1960 A) 19 62 5) 1964
6) 1966 7) 1968
Kraft production>Sulfite production Production of fodder yeast from sulfite s p e n t liquor Production of furfural a s dissolving kraft pulp by products First production of hardwood kraft liner in the w o r l d Production of l i g n i n rubber Production of polystyrene f o a m paper P r o d u c t i o n of refiner groundwood Construction of chip exclusive c a r r i e r Pulp wood: Hardwood>Softwood First production of polymer paper in the world Production of x y l o s e a s dissolving kraft pulp by-products Table 7 Consumed pulpwood statistics (1,000 m ) 3
Year 1960 62 64 66 68 70 72 73 74 75
Softwood 7.861 7.674 7.894 8.132 9.348 12.018 13,550 15.131 15.912 14,096
Hardwood 4,481 6,516 8.538 10,352 12.698 16.325 17.258 17.783 17.163 14.553
Total 12.342 14.190 16.432 18.482 22.046 28.343 30.808 32.914 33.075 28,649
Table 8 Supplied p u l p w o o d statistics(1,000m ) 3
Year 1960 65 67 68 70 72 73 74 75
Domestic Roundwood Chip 7,983 7,673 9.975 7,401 6,566 4,419 3,712 3,799 2,672
3.040 8.479 10,005 11.950 16.050 17.966 17,446 17,716 14,324
Imports Roundwood 193 207 163 299 559 370 667 1,232 578
Chip
—
254 1,401 2.927 4.726 7.159 10.556 12.820 11,213
Total 11.216 16.613 21,544 22.577 27,901 29.914 32.381 35,627 28,787
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Table 9 Imported p u l p w o o d statistics(1,000m ) 3
Year
North America
—
1960 65 67 68 70 72 73 74 75
253 U02 2,909 4,091 5.435 7,501 8.729 7,533
Soviet Union 193 167 97 55 257 128 417 579 723
O c e a n i a Others
— — —
— 41
65 3 259 779 158 854 1,112 2,349 956 4.744 3,535
Total 193 461 1.564 3,226 5.285 7,529 11,223 14.052 11,791
TablelO W o o d s p e c i e s a s p u l p w o o d Wood s p e c i e s Softwood
Domestic w o o d
Hardwood
8.
Foreign wood Soviet U S.A. Southern a r e a Domestic w o o d
pine. fir. s p r u c e , hemlock. sugi(Cryptomeria), cypress, l a r c h , hiba(Thujopsis) spruce, fir, Scotch pine, larch Douglas f i r, hemlock. white fir, spruce, cedar merkusii p i n e , r a d i a t a pine b e e c h , birch, alder, oak,tabu(Machilus), shii(Shiia)
Foreign w o o d Soviet Southern area
white birch, e l m , a s p e n , a s h mangrove, eucalyptus, lauan, gum(waste wood)
Table 11 Outlook of supply a n d d e m a n d of pulp a n d p a p e r ( U n i t : 1,0001) Items Pulp Demand Production Capacity Rate of operation,% Paper Demand Production Capacity Rate of operation^
1973
1974
11.475 10,781 1Q200 9.558 11.461 11.868 89.0
80.5
16.954 14.246 ]6J§2& 14.433 16,498 17,935 100.8
80.5
1975
1976
1977
1978
10,445 9.395 12,472
10.661 9.311 12.460
11.131 9.581 12,779
13,448 10.848
75.2
74.7
14,564 14.100 19.967
15.523 15,337 20.058
70.6
76.5
75.0
— —
16,227 20.752 16 7QQ 20.468 20.740 f
80.5
— —
178
a l o n g range view o f p u l p raw
CELLULOSE
AND
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SCIENCE
materials.
Resource developments i n o t h e r c o u n t r i e s Table 12 summarizes the r e s o u r c e development i n o t h e r c o u n t r i e s . At p r e s e n t , Japan i s p u r s u i n g a p a t t e r n which w i l l c o n t r i b u t e more t o the p r o s p e r i t y o f the h o s t c o u n t r i e s , i n o t h e r words, the i n d u s t r y i s t r y i n g t o go i n t o t i e - u p s w i t h the h o s t c o u n t r i e s t o undertake p l a n t a t i o n and even p u l p and paper p r o d u c t i o n i n t h e s e c o u n t r i e s . One o f the s u c c e s s f u l c a s e s o f the economic c o o p e r a t i o n i n the manner mentioned above i s the p r o j e c t i n B r a z i l . Waste paper T a b l e 13 shows the o r i g i n o f waste paper i n Japan. The share o f waste paper was i n 37~ 4 1 % o f paper and paperboard p r o d u c t i o n from 1969 t o 1974. The i n d u s t r y i s a l s o t r y i n g t o make more use o f waste paper as p u l p raw m a t e r i a l . F o r t h i s purpose, The C e n t e r f o r the P r o m o t i o n o f the Use o f Waste Paper has been e s t a b l i s h e d t o f a c i l i t a t e the c o n s t a n t s u p p l y of waste paper and t o i n c r e a s e the share o f waste paper. The c h r o n i c i n s u f f i c i e n c y o f the waste paper r e c o v e r y system i n Japan has l o n g p r e v e n t e d the i n c r e a se of r e c o v e r y r a t e . At p r e s e n t , the i n d u s t r y w i s h e s to i n c r e a s e the share of waste paper used as raw mater i a l t o 45% by 1 9 8 5 . Non-woody p l a n t f i b e r The use of r i c e straw as raw m a t e r i a l was e a r l i e r t h a n t h a t of wood, t h a t i s i n 1878. The i n c l i n a t i o n o f c o l l e c t i o n season, the i n convenience o f c o l l e c t i o n , t r a n s p o r t a t i o n and s t o r a g e , low p u l p y i e l d and so on have p r e v e n t e d the i n c r e a s e o f straw p u l p p r o d u c t i o n . R e c e n t l y , a l l straw p u l p m i l l s stopped the p r o d u c t i o n o f i t i n Japan, because the e f f u i e n t problems was f u r t h e r t a k e n p a r t . However, from a p o i n t of f u t u r e s h o r t a g e o f p u l p raw m a t e r i a l , r i c e s t r a w s h o u l d be used a g a i n . I n the case o f r i c e s t r a w p u l p p r o d u c t i o n , a new p u l p i n g way must be found out, because the ash c o n t e n t o f r i c e s t r a w (about 17%) i s more t h a n t h a t o f wheat s t r a w (about 8%). Also, new s t r a w p u l p m i l l would be b e t t e r t o o p e r a t e i n s m a l l p r o d u c t i o n c a p a c i t y from a p o i n t o f the p o s s i b i l i t y o f easy c o l l e c t i o n . I n Japan, we can e s t i m a t e 1 2 , 0 0 0 , 0 0 0 t / y e a r of r i c e straw. Supposing t h a t the i n d u s t r y w i l l use 3 , 0 0 0 , 0 0 0 t / y e a r of r i c e straw and p u l p y i e l d i s 40%, about 1 , 2 0 0 , 0 0 0 t / y e a r o f s t r a w p u l p a r e t o be produced. C o n c e r n i n g p u l p p r o d u c t i o n from non-woody p l a n t , one company i s now making the p l a n t a t i o n o f some h e r b s , s o - c a l l e d pulp grass.
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P o l l u t i o n problems The p u l p and paper i n d u s t r y must meet t h e r e g u l a t i o n o f a n t i - p o l l u t i o n s e t by t h e government and t h e l o c a l a u t h o r i t i e s , a l t h o u g h t h e government has p e r m i t ted a t r a n s i t i t i o n a l p e r i o d d u r i n g which the i n d u s t r y can improve t h e p r o d u c t i o n system t o meet t h e e n v i r o n mental standards. The i n d u s t r y was r e q u e s t e d t o a c h i e v e BOD and COD 1 20 ppm and SS 150 ppm by June i n 1976. The s t a n d a r d s s e t by t h e l o c a l a u t h o r i t i e s a r e even more s t r i c t . A new paper m i l l e s t a b l i s h e d i n 1974 has agreed upon 12 ppm o f BOD w i t h t h e l o c a l a u t h orities. T h i s m i l l has been a d o p t i n g t h e c o a g u l a t i o n and a c t i v e carbon t r e a t m e n t s o f e f f l u e n t s . P o l l u t i o n abatement i n e x i s t i n g p u l p and paper m i l l s The e x i s t i n g p u l p and paper m i l l s have improved the closed' system o f t h e p r o c e s s c o n s i d e r a b l y . Anyhow, as a commonsence, p o l l u t a n t s s h o u l d be t a k e n i n t h e production processes. I t i s a l s o c o n s i d e r e d i n what p r o c e s s t h e s u r p l u s m a t e r i a l s s h o u l d be d i s c h a r g e d . Decrease o f w a t e r consumption I t i s well-known t h a t p u l p and paper m i l l s a r e s t r u g g l i n g t o save t h e w a t e r consumption. T h i s i s a c h i e v e d by i n c r e a s i n g the use o f r e c o v e r e d water and r e c y c l i n g w a t e r . There i s a n o n - e f f l u e n t paper board m i l l w h i c h i s u s i n g waste paper, a l t h o u g h t h e w a t e r consumption i s a c t u a l l y 2 - 3 ^/t paperboard. T h i s m i l l announced t h a t t h e i n c r e a s e o f o p e r a t i o n temperature cused by none f f l u e n t s o p e r a t i o n has p r e v e n t e d t h e s l i m e t r o u b l e . The m a t e r i a l y i e l d was about 90% s e v e r a l y e a r s ago, but a t p r e s e n t i n c r e a s e d t o 9 6 ~ 9 7 % * a f t e r t h e improvement o f the p r o c e s s e s . That i s , t h e p r e v i o u s p o l l u t a n t s was t o be t a k e n i n t h e p r o d u c t s , and t h e r e i s no d i f f e r e n c e from t h e former q u a l i t i e s o f paperboard. Although people says t h a t t h i s i s p o s s i b l e o n l y i n a paperboard m i l l , t h e r e may be a few p r o c e s s e s w h i c h c o u l d be a p p l i e d i n t h e p r o d u c t i o n o f c o n v e n t i o n paper. Development o f p o l l u t i o n f r e e p u l p i n g There a r e two p r o c e s s e s w h i c h have been p r o g r e s s e d by t h e use o f p i l o t p l a n t ; PFP p r o c e s s by Japan P u l p and Paper I n s t i t u t e and HOPES p r o c e s s by Toyo P u l p Company. Both p r o c e s s e s have been f i n a n c e d by s u b s i d y o f t h e Government. Another p u l p i n g p r o c e s s , s o - c a l l e d a l k a l i methanol p u l p i n g has been s t u d y i n g by us s i n c e 1 9 7 4 . As shown i n F i g u r e 1, t h i s p r o c e s s i s from sodium h y d r o x i d e c o o k i n g o f c h i p s and d e f i b r a t i o n o f cooked c h i p s f o l l o w e d by t h e r e p e a t e d t r e a t m e n t s w i t h chemi*c a l s such as c h l o r i n e , c h l o r i n e d i o x i d e and sodium
180
CELLULOSE AND FD3ER SCIENCE
hydroxide for a s e l e c t i v e d e l i g n i f i c a t i o n . For an example, t h e r e i s C - E - H - E - D - E - D sequence a f t e r p r e cooking. P u l p y i e l d i s 6 0 - 7 0 % depending on the p u l p i n g c o n d i t i o n s , and the spent l i q u o r i s w h o l l y r e c o v e r ed, c o n c e n t r a t e d and b u r n t t o o b t a i n s m e l t of sodium c h l o r i d e and sodium c a r b o n a t e . Sodium c h l o r i d e i s s u b j e c t e d t o e l e c t r o l y s i s t o produce c h l o r i n e and sodium h y d r o x i d e . C h l o r i n e i s used t o produce c h l o rine dioxide. The advantages o f t h i s p r o c e s s a r e i n low t e m p e r a t u r e p u l p i n g under normal p r e s s u r e , no o f f e n s i v e odor l i k e k r a f t p r o c e s s and f r e e c o n t r o l l i n g o f p u l p y i e l d depending on the p u l p q u a l i t i e s r e q u i r e d . And the p o l l u t i o n load i s also quite small. However, h i g h power consumption and c o r r o s i o n o f the r e c o v e r y e q u i p ment s h o u l d be p o i n t e d o u t , as the d i s a d v a n t a g e s of t h i s process. Paper t e n d s t o be low i n o p a c i t y and t e a r i n g s t r e n g t h , because p u l p c o n t a i n s much h e m i cellulose. Flow c h a r t o f the HOPES p r o c e s s w i l l be shown i n Figure,2. T h i s p r o c e s s i s from two s t a g e p u l p i n g w h i c h i s from sodium h y d r o x i d e t r e a t m e n t a t Ί 6 0 - 1 7 0 ° C and sodium h y d r o x i d e - o x y g e n t r e a t m e n t a t 1 2 0 - 1 3 0 ° C under oxygen p r e s s u r e l e s s t h a n 1 Okg/cm . A modified Kamyr d i g e s t e r i s t o be a d o p t e d . Spent l i q u o r i s s u b j e c t e d t o a wet combustion p r o c e s s t o decompose o r g a n i c m a t t e r s and t o r e c o v e r sodium c a r b o n a t e . Pulp y i e l d i s s a i d t o be 2 - 3 % h i g h e r t h a n k r a f t p u l p and pulp strength equivalent to k r a f t pulp i n breaking l e n g t h and b u r s t s t r e n g t h and t o s u l f i t e p u l p i n t e a r strength. Toyo P u l p Company announce t h a t t h e y have a f a i r p r o s p e c t o f i n d u s t r i a l i z a t i o n and a 50 t/D p l a n t i s now undr c o n s t r u c t i o n . Flow c h a r t o f a l k a l i - m e t h a n o l p u l p i n g p r o c e s s i s shown i n F i g u r e 3 . Wood c h i p s a r e cooked w i t h 4 0 % methanol i n aqueous sodium h y d r o x i d e or sodium c a r b o nate a t the maximum t e m p e r a t u r e o f 1 6 0 - 1 8 0 ° C . The advantages a r e i n about 3~5% h i g h e r p u l p y i e l d t h a n k r a f t p u l p and i n e q u i v a l e n t p u l p s t r e n g t h t o k r a f t pulp. The development o f t h i s p r o c e s s depends on methanol p r i c e . I t i s worth n o t i n g that a part of methanol comes from wood c o n s t i t u e n t s . E n v i r o n m e n t a l p r o t e c t i o n s i t u a t i o n The p u l p and paper i n d u s t r y has t o meet a n t i - p o l l u t i o n s t a n d a r d s s e t by the government. I t i s assumed t h a t the g o v e r n ment w i l l s h i f t i t s c o n t r o l system from BOD and COD t o TOD and TOC, and a l s o from ppm base t o t o t a l l o a d base of p o l l u t a n t s . F u r t h e r m o r e , the l o c a l a u t h o r i t i e s s e t the r e g u l a t i o n f o r the o f f e n s i v e odor o f k r a f t m i l l .
Japanese Pulp and Paper Industry
NAKANO
(Chip)
NaClOa Electrolysis
Softening & . /MnHV* n
NaClOa*
! NaCl
(CÎO2J-—->(Cli>(HCI) (Hj)
,ΟΕ-Η-Ε-Ϊ
KCIOI)->(NaClO>-
'D-E-D /
Lignin removal
(Cl > 2
\k lectro ly s l s f - - - - K N a O H f / KiÀr 1 \
(NaCl)
