PAPER AND PULP INDUSTRIES

ShruthiSoumya RishikaAnushaNikithaAbhijna

PULPANDPAPER INDUSTRIESINTRODUCTION...

HISTORY OF PAPER

HISTORY….. Paper has a rich, colourful history which has spanned

the world's geography and its cultures. Tracing its development , offers us insight into humanity's relentless imagination, creativity and sometimes folly.

Paper as we know it today comes from another source - China.

it wasn't until the 3rd century that the secret art of papermaking began to creep out of China, first to Vietnam and then Tibet. It was introduced in Korea in the 4th century and spread to Japan in 6th.

Papermaking spread slowly throughout Asia to Nepal and later to India. It made its true push westward in 751AD

The birth of the modern paper and printing industry is accredited to JOHANN GUTENBURG

In Europe and America,in the 18th century the mass-production of paper became a thriving industry supplying huge volumes of paper for the production of newspapers, books, magazines, paper bags, toilet paper, money and a huge variety of other purposes - including clothing, chimney's and even coffins!

INDUSTRIAL TRENDS…… Papermaking today is a large, capital-intensive industry, characterized by

high-speed machines and complex systems of control for manufacturing to close tolerances thousands of products vital to education, communications, marketing, packaging, construction, etc. 

Throughout the 19th century, pulp and paper was largely a domestic industry, serving the gradually increasing needs

With the 1960s came the greatest surge of expansion in the industry since the 1920s, spurred by provincial governments’ eagerness for new industrial investment .

Over the past 20 years the most significant development in the industry's fibre requirements has been the tremendous increase in the use of wood chips, reject lumber and other wood residues from saw mills . Also, large areas of public forestland was made available to obtain raw material from..

INDIAN PAPER INDUSTRY SCENARIO……

These paper mills are manufacturing industrial grades, cultural grades and other specialty papers. The paper industry in India could be classified into 3 categories according to the raw material consumed.

Wood based Agro based & Waste paper based

The Indian Paper Industry is among the top 12 Global players today, with an output of more than 13.5 Million tonnes annual with an estimated turnover of Rs. 35000 Crores.

Paper Industry in India is moving up with a strong demand push and is in expansion mode to meet the projected demand of 20 Million tonnes by 2020. Thus paper industry in India is on the growth trajectory and is expected to touch 8.5% GDP in the coming years. Therefore, the growth of Industry will out span the present growth rate of 6.5%.

The average salary for a chemical engineer in the Indian paper and pulp industry is around 7 l.p.a.

PRINCIPLE BEHIND ……… The pulp and paper industry comprises manufacturing

enterprises that convert cellulose fibre into a wide variety of pulps, papers and paperboards. About 95% of their fibre comes from wood from forests, the balance from wastepaper and a very small quantity of linen and cotton rags.

Wood is reduced to fibre by mechanical means or by cooking in chemicals.

The fibres are then mixed with water, adhering to one another as the water is removed by pressure and heat.

This is the fundamental principle of papermaking.

OVERVIEW……

RAW MATERIALS FOR THE PULPING INDUSTRY

Requisites for Cellulose raw materials

Ample supply Available to pulp mill throughout the year Should not deteriorate in storage High yield of quality fibre Capable of being collected and stored in a small area

and transported, if necessary at low cost Cost of conversion to paper must be low Quality of paper made must be competitive Must not have a higher priority use

Major inputs for pulp production Fiber

softwoodhardwoodnon wood fibresrecovered/recycled fibre

Chemicals Energy water

Fibres Softwood Contain more lignin than hardwoods Longer and coarser fibre than hardwoods Strength to withstand stretching and tearing Improves the runnability of paper on the machine. Greater amount of lignin means that more amount of chemicals and

energy Include coniferous and non coniferous woods .... E.g.: pine, spruce

etc.. Hardwoods Provide Smooth surface Primarily used in the production of printing paper because short fiber

pulp improves the printing properties of paper E.g...... Acacia, lemon, gum, birch, eucalyptus, pinus, patula, paper

mulberry, rubber plant wood etc..

Fibres Non wood fibres Annual crops: flax, kenaf, hemp etc.- often grown especially for

paper production agricultural residues: rye, wheat straw, bagasse, etc.. ( vegetable

wastes, fruit pulp etc.. – newer alternatives being researched on) - byproducts of crops grown for other uses

Straw: rice, wheat, bagasse, barley, reeds, etc.. Grasses and reeds: lemon, panni, Ulla, siru, munji,

Sabai grass, bamboo etc... ADVANTAGES OF NON WOOD FIBRES: Non wood fibers can reduce the amount of chemicals needed for

pulping as well as shorten time, thus saving energy. The high cellulose content of cotton linter (85% to 90%) compared

to that of wood (35% to 49% cellulose) and the low lignin content of hemp (3%) make these non wood fibers valuable for papermaking

FibresList of materials Cellulose (%) Lignin

(%) Wood Coniferous 40-45 26-34 Deciduous 38-49 23-30 Non wood Rice Stalk 28-48 12-16 Wheat straw 29-51 16-21 Barley Stalk 31-45 14-15 Kenaf Bast 44-57 15-19

Table shows that non wood not just rich with cellulose fibres but the composition of lignin is also low. So, it is easy to be degraded and consumed short period of time compared to wood fibres in chemical pulping process.

Fibres Recovered fibre (recycled paper) Grade determined by the process used in

manufacturing the virgin pulp when the paper was first made and contaminants added to or picked up by paper in recovery from solid waste or recycle collection process

Contaminants: ink, wax and clay coatings, non fibre filler materials used in paper, adhesives, tape, staples, pieces of plastic, metal, dirt etc

Chemicals For chemical pulping: Sodium sulfite, carbonate, or

hydroxide. In the kraft pulp process the active

cooking chemicals (white liquor) are sodium hydroxide (NaOH) and sodium sulfide (Na2S)

Energy Half of the wood raw material is utilized as chemical pulp fiber.

The other half is utilized as fuel for electricity and heat generation. In fact, a pulp mill has two main lines. Wood is turned into pulp on the fiber line.

Energy is produced on the chemical recovery line from the wood material cooked in the liquor; the cooking chemicals are recovered for reuse. In the chemical recovery line, the black liquor is evaporated and combusted in a recovery boiler, and the energy content of the dissolved wood material is recovered as steam and electricity.

The chemical pulping process generates more energy than it uses.

A pulp mill generates energy for its own use and energy to sell.

Water Water is intricately associated with all the three stages of

paper production namely, pulp making, pulp processing, and paper/paper board manufacturing, and their associated activities of cooking, bleaching, and washing.

With more than 17,000 gallons of water used for every ton of pulp produced, the pulp and paper sector remains the largest user of industrial process water in the U.S. and the second largest in Europe.

About 85 percent of the water consumed in the pulp and paper industry is used only for processing, thus, leading to the generation of large volumes of contaminated wastewater.

It is also one of the largest producers of wastewater. The paper and water industries have worked closely for years to achieve enormous reductions in both fresh water use and the contaminants in wastewater. 

Ideal raw materials based on the requisites and options available:

The largest paper producing countries like China, US, Germany, Japan, Canada, use predominantly wood.

Bamboo is an ideal raw material. India is the first country in the world to use bamboo as the basic raw material for making paper.

Bamboo and pulpable timber continue to be the basic raw materials for the paper industry in India.

Some top paper producing plants in India and their

stats:ITC Limited – PSPD Water and energy consumption per ton of

paper produced: Water: averaging around 43kL Energy: averaging around 1027 kWh Raw material base: Wood: around 52% Imported pulp: around 27% Waste paper: around 21%

Tamil nadu newsprint and papers limited (TNPL) Water and energy consumption per ton of paper produced: Energy: 1522 kWh Water: 55kL Raw material base: Bagasse pulp: 55% Hardwood pulp:35% De-inked pulp: 10%Century pulp and paper (Mumbai, Maharashtra) Water and energy consumption per ton of paper produced: Water: 57 kL Steam: 8.37 tons Power: 1291 kWh Raw material base: Wood, bagasse and recycled fibre

Rainbow papers limited ( Ahmadabad, Gujarat) Water and energy consumption per ton of paper produced: Water: 15 Kl Energy: 544 kWh Raw material base: Waste paper and ready pulpTrident limited (dhaula, barnala, punjab) Water and energy consumption per ton of paper produced: Water: 48 kL Energy: 981 kWh Raw material base: Wheat straw as agro residue raw material for straw pulp – (50-

80%) Eucalyptus and veneer waste from plywood industries for

wood pulp -rest

RAW MATERIALS FOR PAPER PRODUCTION

Fibrous raw materials: Paper pulp: groundwood, chemical, semi

chemical pulps- bleached or unbleached Reuse pulp: recycled or repulped paper

products like newspapers, paperboard etc..mixed with new pulp

Miscellaneous cellulose pulp: straw, linen, cotton, jute, rags

Speciality pulp: inorganic fibres such as asbestos and glass

Non fibrous raw materials: For fillers, sizing and coating, finishing

processesInorganic: Clay, talc, titanium dioxide, zinc sulfide,

calcium carbonate, calcium sulphate, barium sulphate, alum etc..

Organic: Rosin, glue, caesin, waxes, glycerol,

dyestuffs etc..

Types of Pulping Processes Pulp can be divided into two principal types: chemical mechanical pulp. In fact there are more than two types of

pulp . Pulp from recovered paper poses a different challenge for the papermaker as it often has to be de-inked and other contaminants removed.

Mechanical pulping or Groundwood pulping…..

The two processes of mechanical pulping are stone groundwood (fiber is torn from the side of short logs with grindstones) and refiner groundwood (wood chips are passed through disc refiners). Mechanical pulping does not separate the cellulose fiber from the lignin in the wood, while chemical pulping does.

In chemimechanical pulping, the wood is softened with chemicals before grinding. There is also a process called thermomechanical pulping, where the wood is softened with heat and then disc-refined under pressure.

Chemical pulping….. Chemical pulping uses chemicals to separate the cellulose from

the lignin. This creates pulps with different properties that can be used for higher quality paper. The three types of chemical pulping are Kraft, Sulfite, and semichemical.

The Kraft process, also called the sulfate process, involves an alkaline treatment with solutions of sodium sulfide and sodium hydroxide. In 1987 Kraft pulping was 95% of the total chemical pulping.

Sulfite pulping began with the use of calcium as the sulfite liquor base. Today the base has been changed to magnesium, ammonia, or sodium. This allows for the recovery of spent liquor.

The semichemical pulping process involves cooking wood chips in a neutral solution of sodium sulfite and sodium carbonate or sodium hydroxide. Only some of the lignin is removed, and then the pulp undergoes mechanical disintegration.

SULPHATE (KRAFT)PULP

PROCESS!!

DE - BARKING CHIPPING

DIGESTOR

SCREENING

WASHING BLEACHING

DRIED / BALED

Debarking is the process of removing bark from wood. Debarking generally involves the use of industrial machinery into which the log or stake is placed. Generally they are powered by hydraulic motors.

1. DE-BARKING

The wood chips are then cooked in pressurized vessels called digesters. In a continuous digester, the materials are fed at a rate which allows the pulping reaction to be complete by the time the materials exit the reactor. Digestion is done to remove the lignin and hemicellulose content .

Wood chips + NaOh + Na2S ------> Black Liquor

2. COOKING

3. Blow Down Valve & Blow Tank

• Steam from the hot slurry passing through the tank is recovered. This steam is used for the preheating of chips. This tank has high concentration of pulp slurry and low concentration of water.

• Reduces the pressure of steam from 80 to 10 atm before entering the blow tank.

4. SCREENINGScreening of the pulp after pulping is a process whereby the pulp is separated from large shives, knots, dirt and other undigested residues. The accept is the pulp. The material separated from the pulp is called reject.5. WASHING

Cooking liquors are separated from the cellulose fibers.  Pulp washers use counter current flow between the stages such that the pulp moves in the opposite direction to the flow of washing waters.

• Bleaching of wood pulp is the chemical processing carried out on various types of wood pulp to decrease the color of the pulp, so that it becomes whiter.

6. BLEACHING

• Traditionally chlorine based oxidizing agents were used for this process but due to the formation of dioxins and other undesirable products, the usage of chlorine has been discontinued.

• In the modern and improved bleaching stage, hydrogen peroxide is added along with sodium hydroxide, which activates the peroxide.

Lignin content

decreases.

ADVANTAGES :Q. WHY THIS PROCESS? 1. Pulp produced is stronger than that made by

other pulping processes.

2. Acidic sulfite processes degrade cellulose more than the kraft process, which leads to weaker fibers.

3. Mechanical pulping processes leave most of the lignin in the fibers.

4. The kraft process can use a wider range of fiber sources than most other pulping processes.

•The black liquor (lignin-rich) produced from the Sulfate pulp production contains 95-98% of digested chemicals.

• To reduce air and water pollution and to balance economy of operation, these chemicals should be removed before disposal.

CHEMICAL RECOVERY

FROM BLACK LIQUOR

BLACK LIQUOR IS SEPERATED FROM PULP IN WASHING

FLOW SHEET

MULTI EFFECT EVAPORATOR• It is a series of single

effect evaporators of 5-6 stages of calandria equipment followed by disk evaporators .

• After the first step the black liquor is about 20 - 30% solids. At this concentration the  rosin   soap rises to the surface and is  skimmed off.

. The weak black liquor is further evaporated to 65% or even 80% solids and burned in the  recovery boiler to recover the inorganic chemicals for reuse in the pulping process. .

MIX TANK

•Organic carbon burns in smelting furnace , supplying necessary heat and CO2 . • The combustion is carried out such that sodium sulphate is  reduced to sodium sulphide by the reaction : NaR(lignin salt) +air Na2CO3 + CO2

RECOVERY BOILER•Molten slag is produced • Here organic carbon present in black liquor is burned.• High pressure 28 atm to 30atm steam is produced.•The reaction that takes place inside furnace is : Na2SO4 + 2C------> Na2S + 2CO2

DISSOLVING TANK The molten salts from the recovery

boiler are dissolved in a process water known as weak wash.

This process water, also known as weak white liquor is composed of all liquors used to wash lime mud and green liquor  precipitates. The resulting solution of sodium carbonate and sodium sulphide is known as "green liquor .

This liquid is mixed with calcium oxide , which becomes calcium hydroxide in solution, to regenerate the white liquor used in the pulping process through an equilibrium reaction :

Na2S + Na2CO3 + Ca(OH)2 ←→ Na2S + 2 NaOH + CaCO3

CLARIFIER A clarifier is

used as a filter to remove solid particulates or suspended solids from liquid

It separates as filtrate and sludge .

Filtering medium is monel metal .

WASHING TANK Impurities

are washed away in this tank after clarifying.

CAUSTICIZING TANK Calcium carbonate  precipitates

from the white liquor and is recovered and heated in a lime kiln where it is converted to calcium oxide  (lime):

CaCO3 → CaO + CO2 Calcium oxide (lime) is reacted

with water to regenerate the calcium hydroxide used in reaction :

CaO + H2O → Ca(OH)2 It precipitates lime mud.

Carbonate is causticized by adding Ca(OH)2 .

An OverviewPAPER INDUSTRY

Definition ‘ fourdrinier ‘ method of

production Finishing Chemical additives

Basic Agenda

Paper is a thin material produced by pressing together moist fibers- cellulose pulp , derived from

wood, rags or grasses, and drying them into flexible sheets.

Basic raw materials include-Fibrous : containing groundwood, paper products

(recycled) , asbestos and glassNon-Fibrous: clay, talc ,glue , waxes ,

glycerol ,titanium dioxide , zinc sulfide , calcium carbonate

What is paper?

Method of paper making

Modern papermaking began in the early 1800s in Europe with the development of the Fourdrinier machine, which produces a continuous roll of paper rather than individual sheets. These machines have become very large, up to 500 feet in length, producing a sheet 400 inches wide, and operating at speeds of over 60 mph (100 km/h).

The Fourdrinier press

WorkingThe Fourdrinier machine is made of four sections – Forming Section or Wet End, Wet Press Section, Dryer Section and

Calendar Section.

Forming section / wet end

1.Headbox2.Press Roll3.Forming Board4.Wire5.Suction Boxes6.Suction Couch Roll7.Wire Driving Roll

HeadboxBecause wood pulp fiber has a strong tendency to clump, it needs to start off with a very high percentage of water content, allowing the pulp to have an even distribution, the slurry (or furnish) held in the Headbox which contains around 99% water.RollersThe furnish travels down the Slice onto the revolving Wire at the Breast Roller point of contact and then over a series of relatively small, parallel rolls of steel or brass tubing called "table rolls." It then passes over several suction boxes, under a roll covered with woven or parallel wires, called a "dandy roll," and over one or more additional suction boxes. Basic function-to keep the wire is at the desired degree of tightness

Forming board device found under the wire on Fourdinier paper machines, just after the headbox; used to prevent premature removal of too much water during sheet formation.

WireFine mesh polyester fabric on which the paper sheet is formed by stock draining through it 

Suction boxesaka ‘Uhle Box’  is found in the press section; used to remove water and detergents from the press felts.

Suction couch rollsSuction rollers hold the furnish to the mesh and help remove the water content.  By the time the paper or web has reached the Wet Press Section the consistency has gone from 0.5% pulp content to 25%.

wire driving rollIt drives the wire with the furnish on top to the next section-the wet press

Wet press sectionThe Wet Press Section carries the wet web between a series of rollers under high pressure to squeeze more water from the paper, much like a mangle.  The Felts (polymeric fabrics) support the web and also aid water removal by absorption.  As the web enters the third section the paper web consistency can be as high as 40%.Wet web strength factors-

Fiber lengths Moisture content Latency(kinked,curled fibers) Inter fiber friction (affected by refining , surfactants ) Surface tension Process variations

Drying sectionSteam heated rollers in the Dryer Section cause further water removal through evaporation .  It is in the Dryer Section that the web will be treated with Sizing to change the characteristics of the paper and via a coating unit, the surface will be covered with calcium carbonate or china clay for coated papers such as gloss, silks and velvet types. The stock is usually about 95% solids by the time it comes off the last dryers.

Calendering  A calender is a device with two or more

rollers through which the paper is run. The compression of the rollers and the application of heat give the paper its smooth and glossy properties.  It also gives it a more uniform thickness. The pressure applied to the web by the rollers determines the finish of the paper.

After calendering, the web has a moisture content of about 6% (depending on the furnish). It is wound onto a roll called a tambour or reel, and stored for final

cutting and shipping

Finishing

• CoatingCoating improves the opacity, lightness, surface smoothness, lustre and color-absorption ability of paper.

Coating means that a layer is applied to the paper, either directly in the papermaking machine or separately.

Varieties of coated paper range from pigmented to cast-coated.

The coat consists of a mix of pigments, extenders such as china clay and chalk, and binders such as starch or latex.

In addition, various chemicals are added to give the paper the desired characteristics.

Why do we need to add additives? Improves fiber to fiber bonding Retain fiber & fines, giving better yield from the

same raw material Better glaze & stiffness Increase in breaking length, double fold, tear

factor & other strength properties w.r.t. writing / printing paper industry.

Improves the formation of paper and fiber distribution

Chemical additives

Wet strength additive : ensures that the paper retains its strength when wet. Very important for making tissue papers. Chemicals used are urea formaldehyde ,poly-

amines Dry strength additive : chemicals which enhance the strength of the

paper at its normal condition. includes compression strength, bursting strength, tensile breaking strength etc. Typical chemicals used are as cationic starch and polyacrylamide (PAM) derivatives--acts as binder of fibers

Colorants : Basically used to give the paper a specific color, improving the tone of the paper at the same time.

Optical brightening agents: makes paper more white by absorbing UV light from fluorescence and re-emits in the blue region

Types of additives

Total chemical additives consumption

APPLICATIONS…. Paper can be produced with a wide variety of properties, depending on its intended

use.

For representing value: paper money, bank note, cheque, security , voucher and ticket

For storing information: book, notebook, magazine, news paper, art & letters. For communication: between individuals and/or groups of people. For packaging: corrugated box, paper bag, envelope, Packing & Wrapping

Paper,  and wallpaper. For cleaning: toilet paper, handkerchiefs, paper towels and facial tissue  For construction: papier-mâché, origami, paper planes, quilling, paper

honeycomb, used as a core material in composite materials, paper engineering, construction paper and paper clothing

For other uses: emery paper, sandpaper, blotting paper, litmus paper, universal indicator paper, paper chromatography, electrical insulation paper (see also dielectric and permittivity) and filter paper

Why should we recycle paper?Recycling 1 tonne of paper :

1.Saves approximately 17 trees.2.Don’t use approximately 380

gallons of oil.3.Saves 4000KW of power.4.Saves 3 cubic yards of landfill

space.5.7000 galloons of water.