Pulp and paper industries

1. CEP – 101G CHEMICAL PROCESS TECHNOLOGY (IPE)
2 Hours / week, 2 Credits
Pulp and Paper Industries: Raw materials, mfg. of different types of pulp paper boards, black lacquer recovery,
deinking of waste paper, pulp and paper industries in Bangladesh. Soap and Detergent Industries: Raw materials,
mfg. of different types of soap, recovery of the glycerin, classification of the detergents, types of surfactants,
industrial processing for the alkyl aryl sulphonates (AAS), Advantages of detergent over soap, environmental
pollution by detergents. Biodegradability of detergents Introduction of Chemical fertilizer: Nitrogenous fertilizer:
Raw materials of ammonia production of synthesis gas in ammonia plants, technology of urea manufacturing;
Process used in Urea industries of Bangladesh. Cement industries: Raw materials, Composition, properties and uses
different types of cements, Manufacture of cement by different methods, setting and hardening of cement, testing
of cement. Lubricants: Various types of lubricants, Production of lubricants, Properties of Various types of
lubricants.
References:
1.G.N Pandey A Text Book of Chemical Technology Vol. I and II
2.N. Austin Chemical Process Industries.
3. Anderson and Winzet Introduction to Chemical Engineering
4. Riegl’s Industrial Chemistry
5. B. K. Sharma Industrial Chemistry
6. S.S. Dara A text book of Engineering Chemistry.

2. Lecture Prepared by
Rahatun Akter
Assistant Professor
Dept. of Chemical Engineering and Polymer Science
Shahjalal University of Science and Technology

3. Course Content and Course Learning Outcomes (CLOs):
Course Learning Outcomes (CLOs): at the end of the Course, students will be
able to-
Course Content CLOs
Pulp and Paper Industries: Natural source of the cellulose, constituents associated with cellulose, mfg. of
different types of pulp paper boards, black lacquer recovery,
deinking of waste paper, pulp and paper industries in Bangladesh.
CLO1
CLO2
CLO1: Discuss about the basic principle of paper making
CLO2: Process and draw the flow diagram of industrial process.

4. Pulp and Paper Industries

5. Pulp and Paper Industries in Bangladesh
BCIC - Bangladesh Chemical Industries
• BCIC now operates only the Karnaphuli Paper Mills (KPM)
producing quality paper as well as packaging paper with yearly
capacity of 30,000 MT and it was commissioned in 1953.
• Other mills under BCIC now closed include:
• KNM, SPPM and NBPM. The Khulna Newsprint Mill (KNM),
only newsprint producing plant began production in 1959
with an annual capacity of 50,000 MT.
• The North Bengal Paper Mill (NBPM) was commissioned in
1973 with the capacity of 15,000 MT and it produced writing
and printing paper using bagasse.
• The Sylhet Pulp & Paper Mill (SPPM), the only pulp producing
plant based on reeds began production in 1975 with an
annual production capacity of 20,000 MT.
• The Magura Paper Mills producing packaging paper around
15000 MT per year is a joint venture with BCIC.
• BCIC used to produce around 90% of the total paper used in
Bangladesh 25 years ago. BCIC/KPM is today producing < 5 % of
the total paper used in Bangladesh.
The private sector has taken over the paper sector
in the country.
• The private sector paper mills includes:
• T.K. group (paper, board, tissue mill)
• Basundhar group (paper, tissue, newsprint)
• Creative paper mill
• Capital paper mills
• Hakkani paper mill
• Hossain pulp & paper mills, etc.
Although there are almost 80 paper mills, only KPML is
the integrated pulp and paper industry in Bangladesh.
All other mills do not produce pulp but fully
dependent on foreign pulps and recycle fibre. The
capacity of KPML was 100 tpd, but now producing
around 20000- 25000 MT/yr. The share of KPM is less
than 5% of total paper production in the country, but
KPML produces both bleached and unbleached virgin
pulps.

6. Major Raw materials
The basic raw material of paper is cellulose in the form of fiber. Cellulose fiber
occurs in many vegetable tissues, from which it can readily be extracted by mechanical
or chemical means.
Soft wood (SW) spruce, pine; and hard wood (HW) eucalyptus, birch, beech, acacia, etc. are the
main fibre source in major pulp and paper producing countries in the world.
• The main raw materials in
BD are bamboo, mixed
tropical Hard Wood,
bagasse, rags etc.

9. Major Raw materials
The basic raw material of paper is wood, bamboo, rags, recycled papers etc.

10. Manufacture of paper
Manufacture of
pulp
Beating, refining,
filling, sizing, and
coloring
Manufacture of
paper

12. Manufacture of Pulp
Slashed
Debarked
Mechanical
Process
Sulphate pulp
Soda pulp
Sulphite pulp
Chemical
Process

13. Manufacture of Pulp (Debarking)
Debarking usually carried out by two ways:
1. In the first method, continuous rotating cylindrical or stationary machines
fitted with agitating cam are used. In the case of drums, the wood is
introduced into the upper end of a rotating drum immersed in a tank partly
filled with water, where it is tumbled. The bark is rubbed off and the clean
wood discharged at the other end.
2. The debarking can also be carried only by the mechanical friction, or by
applying high pressure water jets to individual logs by means of hydraulic
barkers. Water jets are directed against the log by means of hydraulic
barkers in such a manner that the bark is broken up and removed.

14. Manufacture of Pulp

15. Manufacture of Pulp (Mechanical Process)

16. Manufacture of Pulp (Mechanical Process)

17. Manufacture of Pulp (Mechanical Process)
https://youtu.be/HZLsDPKgCUk https://youtu.be/8u6GkDNd6GM

18. Manufacture of Pulp (Chemical Process)
Sulphate Soda Sulphite
High Grade Paper

20. Manufacture of Pulp (Sulphate or Kraft process)
White liquor:

21. Manufacture of Pulp (Sulphate or Kraft process)

22. Manufacture of Pulp (Sulphate or Kraft process)
• This pulp is prepared by an alkaline process using almost any kind
of hard or soft wood as the raw materials. The logs are slashed,
debarked and then disintegrated into small chips by means of
chippers.
• The chippers are large rotating disk containing four or more long
heavy knives. The disintegrated chips are screened on either
rotary or vibrating screens. The oversized chips retained by the
screens are passed through crushers or chippers to reduce them
to proper size.
• The desired sized chips are then digested under pressure (100
kPa-900 kPa) ( in stationary or rotary digesters made of stainless
steel) and temperature of 170 ⁰C with sodium sulphide and
caustic soda.
• The digestion or coking, takes about 1.5 hours. These treatments
dissolve incrusting lignin of lignocellulose leaving behind more or
less chemically pure fibrous cellulose.
• The fibrous material, after separation from the cooking liquor is
washed with water.

23. Manufacture of Pulp (Sulphate or Kraft process)
• The washed pulp is allowed to pass
through knotters, riffles, and screens to
separate any small silver or uncooked
wood and finally to filters and thickeners.
The thickened pulp is bleached with
chlorine and washed again. It is then
beaten into pulp with water in a pulp
beater. During beating, long fibers are
reduced to minute shreds, which absorb
and hold more water. The washed pulp
(after bleaching) may be rethickened to
convert it into sheets dry enough to fold
into a bundle, called lap.
• The lapping is done on a wet thickener which consists of a cylinder immersed into a vat, filled with
stock solution and fitted with an end felt belt, which carries the pulp sheet through squeeze rolls and a
series of press rolls. The laps thus obtained contain 35-40% air dry fibre. These laps are then stacked in
hydraulic presses and subjected to pressure of about 3000 psi. The resulting laps now contain 50-60%
air dry fibre.

24. Manufacture of Pulp (Sulphate or Kraft process)
White liquor:
https://youtu.be/2Uh3XIadm1A
https://youtu.be/dwctkBfPyvs

25. Manufacture of Pulp (Black liquor recovery)
White liquor:
• The black liquor is concentrated, burned, smelted and limed. As a
result of smelting, organic compounds are broken down, the carbon
is burned away and inorganic compounds are melted. Moreover,
sodium sulphate is converted into sodium sulphide, according to
the reaction:
• The molten smelt is then dissolved in the dissolving liquor (coming
from the causticizing plant), to obtain a characteristic green liquor.
It is allowed to stand for few hours, as a result of which, insoluble
impurities settle down at the bottom. Slaked lime prepared from
the recovered 𝐶𝑎𝐶𝑂3 is then added to the green liquor to causticize
any sodium carbonate still present in it.
• The 𝐶𝑎𝐶𝑂3 slurry is separated in settlers, rotary continuous filters,
and passed to a lime kiln to get CaO for reuse in the process. The
filtrate or white liquor containing caustic soda, sodium sulphide,
and traces of sodium carbonate, sodium sulphate and sodium
sulphide etc. is used again in the cooking of the fibers.
• Tall oil is also obtained as a byproduct
from the black liquor recovery. It may be
separated from black liquor, either by
means of centrifuges or by floatation
from the concentrated liquors . Tall oil is
used in the manufacture of soap,
emulsion and greases.
https://youtu.be/2Uh3XIadm1A

26. https://youtu.be/2Uh3XIadm1A

28. Manufacture of Pulp (Soda Process)

29. Manufacture of Pulp (Sulphite pulping)

31. Manufacture of Pulp (Sulphite pulping)

32. Manufacture of Pulp (Sulphite pulping)

33. Manufacture of Pulp (Sulphite pulping)

34. Manufacture of Pulp (Sulphite pulping)
• Sulphite pulp is a high quality pulp
and used in the manufacture of
some finest papers including bond
paper.

35. Manufacture of Pulp (Sulphite pulping)
• Sulphite pulp is a high quality pulp and used in the manufacture of some finest papers including
bond paper.

36. Differences between Sulphate and Sulphite pulping

37. Differences between Sulphate and Sulphite pulping

38. Manufacture of Pulp (Rag pulp)

39. Manufacture of Paper
(Beating, Refining, Filling, Sizing, and Coloring)

40. Manufacture of Paper (Beating)

41. Manufacture of Paper (Refining)
https://youtu.be/ON1Q-UzI6yk
In this step, the fiber is deformed, defibered and
dispersed but not cut by the device.

42. Manufacture of Paper (Filling, sizing, coloring)

43. Manufacture of Paper (Filling, sizing)
Fillers

44. Manufacture of Paper (Coloring)

45. Manufacture of Paper

46. Manufacture of Paper (Coloring)
The whole process is carried out mechanically by making use of a machine, called Fourdrinier machine.

49. Fourdrinier Machine: Paper making

50. Fourdrinier Machine: Paper making

51. Paper Manufacturing: Calendering

52. Paper Manufacturing: Calendering

53. Paper Manufacturing: Calendering
• The sheets of paper obtained above are rough
and irregular. They become compact, more
smooth and receive fine glaze when they are
passed through a series of hot and polished
rolls, called polishing cylinders. This process is
called calendaring.
• Raw paper stock thus obtained may further be
converted to its end use by various means,
developing upon the final form of the desired
paper. For example, the printability of paper
may be improved by applying mineral or
pigment surface coating. For basic pigment
coating, clay is used, while for color coatings
dyes are added. After calendaring and finishing
sheets of paper are wound on reels into large
roll. These are then taken to slitting machine for
cutting them into rolls of proper size.

54. Paper Manufacturing: Calendering

55. Paper Manufacturing: Heavy paper
The manufacture of heavy paper, card board or
non-uniform paper is carried out by making use of
cylindrical machines. It consists of 4-7 parallel vats.
Each vat is charged with similar or dissimilar paper
stocks. A wire covered rotating cylindrical dips into
each vat. The paper stock is deposited on the
turning screen as the water inside the cylinder is
removed. The cylinder is so moved farther that the
paper stock reaches the top, where wet layers
adheres to a moving felt which carries it to a press
roll to remove some of the water. This felt and
paper come in contact with the top of the next
cylinder and pick up another layer of wet paper. In
this manner, several layers are united together into
one compact wet sheet. This is passed through
press rolls and on the steam heated drying rolls
and smoothing rolls to get a dry smooth heavy
sheet.

58. Paper : Uses
• Paper is used for writing work, for printing of books, periodicals and
newspapers etc., for making bags, envelops, and other packing
materials.
• Tissue paper has been used in making napkins, toilet papers and light
weight wrapping.
• Colored tissue papers are used for decoration purposes and paper
flowers etc.

59. Sample Questions:
1. What is meant by pulping? 2
2. Sulphite pulping can be used to produce good quality paper, but its application steadily diminishes – justify the
statement. 2
3. What is the difference between pulp and paper? Why bark cannot be used in pulping process? 4
4. Write down the names of common pulping processes. Briefly describe any one of these pulping processes
with a proper flow diagram. 8
5. What are the prerequisite for any cellulose raw material for the pulp and paper industry? 4
6. Briefly discuss about the sulfite process for pulp manufacturing. 8
7. What are different chemical pulping processes? 1
8. What is chemical pulp? Compare three main types of chemical pulp. 3
9. Describe the manufacturing process of pulp from bamboo by using sulfate process. 7
10. How is the debarking done in pulping process? 2
11. Briefly describe the craft process with chemical recovery for the manufacturing of pulp. 8
12. Compare among different types of pulping.
13. What are the essential reactions involved in the preparation of cooking liquor in sulfite pulping? 4
14. What is black liquor? Describe the reactions the recovery of black liquor? 6

60. Sample Questions:
1. What is black liquor? Describe the reactions the recovery of black liquor? 6
2. Why does Mg-based sulfite pulping is suitable than any other bases? 3
3. Write the basic principle of paper making process.
4. What are the pre-requisite for any cellulose raw materials for pulp and paper industry?
5. When and why sizing materials are added during paper manufacturing? 3
6. Why black liquor recovery is necessary for pulp and paper industry. 2
7. Discuss the finishing operation of pulp. 4
8. Compare the raw materials, composition of cooking liquor, cooking conditions, and pulp characteristics of the various
chemical pulping processes. 4
9. Why doesn’t bark use in pulping process? How is the debarking done in pulping process? 3
10. How could wastepaper be made usable? 2
11. What are the significances of using filling, sizing and coloring materials in paper manufacturing process? 4.5
12. Name some different additives used in the manufacturing of paper from pulp. 3
13. Give general functions of Hollander machine. 3
14. How finished paper is obtained from a Fourdrinier machine? Describe briefly with diagram. 6
15. Why Mg(HSO3)2 is used instead of Ca(HSO3)2 in sulfite ppulping process? 3
16. How chemical pulp (kraft) is produced from their raw materials? 7
17. Why are the additives used in paper manufacturing ? 4
18. What are the significances of using filling, sizing, and coloring mateialas in paper manufacturing. 3/4.5
19. Describe the manufacturing process of pulp from bamboo using sulfite process. 7