pulp & paper industries

PAPER AND PULP PAPER AND PULP INDUSTRIES INDUSTRIES

PRESENTED BY: JITENDRA KUMAR (B.TECH AGRICULTURAL ENGINEERING)

TAMILNADU AGRICULTURAL UNIVERSITY

PRINCIPLE BEHIND ………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.

Desirable characteristics of raw materials:Desirable characteristics of raw materials:

Sustained raw material supply Cost effective Long, strong, and soft fibres High cellulose content Low lignin content

RawRaw Materials:Materials:

Bamboo – Have long fibreWoods Soft wood – Conifers / pines Hard wood – Dicotyledons –Casuarinas, Eucalyptus etc.,

Fibrous raw materials: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:Non fibrous raw materials:

Inorganic: Clay, talc, titanium dioxide, zinc sulfide, calcium carbonate, calcium

sulphate, barium sulphate, alum etc..Organic: Resin, glue, waxes, glycerol, dyestuffs etc..

Types of Pulping ProcessesTypes of Pulping Processes

i.Mechanical method of pulping

ii.Chemical method of pulping a.Alkaline method b.Acid method

iii.Semi-chemical method of pulping

Mechanical method of pulping:Mechanical method of pulping:

It is very oldest processGrinding in stone, cleaning, refining, paper making. It is mostly used for newsprint process

Disadvantages: It contain Lignin

Chemical method of pulpingChemical method of pulping

Done through digestion Mostly all coloring material is removed [lignin] It have two different process

◦ Alkaline process◦ Acid process

Semi chemical method of pulping:

It is nothing but partially chemical and mechanical

Cooking is done in digestion, using chemicals de-fibrication is done in mechanical process

DE - BARKING

CHIPPING

DIGESTOR

SCREENING

WASHING BLEACHING

DRIED / BALED

KRAFT PULP PROCESSKRAFT PULP PROCESS

DE BARKING COOKING SCREENING WASHING BLEACHING

Lignin content

decreases.

An OverviewAn Overview

What is paper?What is paper?

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 glass

Non-Fibrous: clay, talc ,glue , waxes , glycerol ,titanium dioxide , zinc sulfide , calcium carbonate

Manufacturing process:Manufacturing process:

There are seven steps1.Log making2.Chipping3.Boiling and pulping4.Pulp cleaning5.Bleaching6.Stock preparation7.Sheet formation

1.Log making: 1-2 m length, 2.5 cm to 45 cm diameter tree logs are used.2.Chipping: Chipper is a equipment Log into small pieces / chips3.Boiling and Pulping: The chips are boiled by using boilers / digesters. Pulping: Isolation of cellulose fibre from boiled chips is called

pulping.

4.Pulp cleaning: Removal of inert materials by screeners

First screening will remove coarse inert material

Second screening will remove small inert material

5.Bleaching:◦ Unwanted colours are removed by using

oxidizing and reducing agents.◦ Mostly chlorine and their compounds are used◦ Single stage cleaning , using calcium

hypochloride [Bleaching powder].◦ Second and multi stage cleaning chlorine gas +

calcium hypochloride + chlorine dioxide are used for making pulp pure white in color.

6.Stock preparation:

To Increase the bursting strength, Tensile strength, tearing strength, Folding endurance, Smoothness and reduce the rattle of the paper

7.Sheet formation It is final product of the paper making Draining the water from the beated stock by using

pressures by several times. Again drying by steam heated cast iron rollers. Calendering to improve the paper smoothness Rolling Cutting by various dimensions Packing.

Recycling 1 tonne of paper :

1. Saves approximately 17 trees.2. Saves 4000KW of power.3. Saves 3 cubic yards of landfill space.4. 7000 gallons of water.

Conserve and Preserve trees