PPT LQ2 PT 3 (Paper) Flashcards
Earliest known paper
200 BCE (China)
Developed papermaking process using mulberry bark, hemp, and rags
105 CE (Lei yang, China - Ts’ai lun)
Pulp masked, pressed, and dried in the sun
105 CE (Lei yang, China - Ts’ai lun)
Used for religion, government, and business
105 CE (Lei yang, China - Ts’ai lun)
Papermaking spread to the middle east during
400 CE
Reached Europer leading the first paper mills
900 CE
First paper machine built
1817 at USA - Gilpin paper mill, brandywine, delaware
Revolutionized speed and production
1817
Led to the decline of hand papermaking
1817
What is the composition of paper
Primarily made from natural fibers mainly wood pulp from trees
Serves as the base material for paper production
Pulp
Can be sourced from softwood (long fibers for strength) or hardwood (short fibers for smoothness)
Pulp
Paper produces over ______ annually
300 million tonnes
One of the largest industrial sectors worldwide
Paper making
Which country are the major producers of wood based pulp
Canada, sweden, finland, japan, brazil, and russia
Wheat straw, bagasse, bamboo
Agro-based fibers
Over _____ countries rely on agro-fibers for 50% of their pulp production
25
These countries are the top producers using non-wood sources
China and india
Why kraft process is the preffered process for paper making?
- Highly efficient and adaptable to different wood types
- Produces stronger fibers compared to other pulping methods
- Allows for chemical recovery, reducing waste and environmental impact
Fourdrinier machine was invested in the early 19th century by
Henry and sealy fourdrinier
It replaced the manual sheet forming methods with a continuous production process
Fourdrinier machine
A machine with increased efficiency, consistency, and scalability, enabling mass paper production
Fourdrinier machine
How does fourdrinier machine works?
Pulp slurry is spread onto a moving mesh conveyor (wire section), allowing
water to drain.
The forming sheet passes through press rollers to remove excess water and
strengthen fibers.
It is then dried using heated cylinders, reducing moisture content.
Finally, the paper is smoothed (calendered), wound into rolls, or cut into sheets
for various uses.
What are the benefits of fourdrinier machine?
- High output with minimal labor
- Consistent paper properties for different applications
What are the raw materials of paper?
Wood pulp, non-wood pulp, recycled paper
Most commonly used raw materials in papermaking, and is derived from both hardwood and softwood trees like oak and pine
Wood pulp
Alternative sources of fiber such as bamboo bagasses, and straw commonly used by developing countries
Non-wood pulp
Inks and contaminants are removed through deinking to reprocess old newspaper, cardboard, and other used papers
Recycled paper
What are the factors affecting material selection?
Softwood fibers & hardwood fibers
Why softwood fibers is affecting material selection?
- Longer and provide strength and durability which is ideal for products like packaging materials
- Pin and spruce
Shorter and contribute to a smoother surface which is beneficial for printing and writing papers
Hardwood fibers
Birch and eucalyptus
Hardwood fibers
Application of sustainable forest management practices ensures a steady supply of wood while minimizing environmental impact
Planting
Reduces reliance on virgin fibers and also supports environmental conservation efforts
Recycling
Tissue papers require softness and absorbency favoring certain fiber types and treatments
Soft fibers
Corrugated boards used in packaging demand high strength and ragidity, necessitating different raw materials and processing methods
Strong fibers
The wood used for paper
production is sourced from forest
plantations, where trees are
selected based on age, size, and
health before cutting them into
manageable wood chunks
Cutting (trees)
which contains tannins and
other unwanted chemicals, is
removed from the logs. The logs are
placed in a debarker, where they
collide with each other and the
walls, causing the bark to peel off.
Debarking
The peeled logs are fed onto a
conveyor belt, which transports
them to a cutter. The cutter reduces
the logs into chips, which are then
stored temporarily before being
used in the cooking process.
Cutting (logs)
Wood chips are cooked with white
liquor containing sodium hydroxide
and sodium sulfide at 160°C for
several hours. This process breaks
down lignin and part of the
hemicellulose through hydrolysis.
Digester
A set of washers separates the pulp
from black liquor before bleaching.
The separated black liquor is then
sent to the evaporators for
recuperation.
Washing
Black liquor is concentrated from solids
using multiple-effect evaporators, with
the first effect powered by low or
medium pressure steam. Vapors are
condensed into warm water, while dirty
condensates are stripped and recycled
to the washers or recausticizing area.
Evaporation
Black liquor is combusted with air to
generate high-pressure steam for power
and process needs. The combustion
produces smelt containing sodium
carbonate and sodium sulfide, which are
essential for chemical recovery, while steam
supports various operational functions like
soot-blowing and preheating.
Recovery boiler
Smelt from the recovery boiler is
dissolved in water, forming green
liquor. Sodium carbonate in the
green liquor reacts with calcium
hydroxide in causticizers to
regenerate sodium hydroxide.
Recausticising
Calcium carbonate (lime mud) is
heated in a lime kiln to produce
calcium oxide (quicklime) and release
carbon dioxide. The quicklime is reused
in the recausticizing process to help
regenerate chemicals for pulp cooking.
Lime burning
The conjugate multiple bonds between
atoms are oxidized to reduce light absorption.
Chlorine is a primary oxidant but more
environmentally friendly chemicals such as
oxygen and peroxide could also be used. The
pulp is bleached and filtered to prevent the
paper from yellowing over time.
Bleaching
The pulp is poured into a continuos mesh
allowing the water to drain and to form the
sheet. It is dried to reduce moisture content
before being fed into the Fourdrinier machine.
This drying process ensures the pulp reaches
the appropriate consistency for the
papermaking process.
Drying
The machine includes the
following unit operations: wire
mesh spread, pressing sections,
heated rollers and cylinders,
calendering rollers, dryers, and
finishing rollers.
Fourdrinier machine
Factors affecting final product quality in pulping are
Chemical and mechanical
Temperature: Ranges from 60-90°C
(140-194°F), depending on the
bleaching stage.
Pressure: Generally conducted at
atmospheric pressure.
Extent of Reaction: Achieves high
degrees of lignin removal to enhance
whiteness.
Energy: Primarily chemical energy
from bleaching agents.
Bleaching
Temperature: Dryer drums
are heated up to 93°C
(200°F).
Pressure: Atmospheric.
Energy: Significant thermal
energy consumption to
evaporate water.
Drying
___ non integrated paper mills with a combined capacity of 1.3 million tons/year
24
Abaca pulp mills exporting 25,000 tons of specialty non-wood pulp annually
4
Most local paper is made from
Recycled materials
Demand for packaging materials and tissue paper is rising, driven by
E-commerce and food delivery
Imported paper dominates the market forcing local mills to shut down with ____ closures recorded
22`
