Recycling paper iip

RECYCLING PAPERUNDER THE GUIDANCE OF: DR. BABU RAO GUDURI

PRESENTED BY: SUJAY PAWAR (PG/M/2015/29)

CONTENTS

• INTRODUCTION• WHAT PAPER IS RECYCLED?• RECYCLED PAPER SOURCES• RECYCLED PAPER PROCESSING• ENVIRONMENTAL IMPACTS• BENEFITS OF RECYCLING PAPER• USES• REFERENCES

INTRODUCTION

• Paper recycling is the process of turning waste paper into new paper products.

• There are three categories of paper that can be used as feedstock for making recycled paper: mill broke, pre-consumer waste and post-consumer waste.

PRECONSUMER WASTE

Pre-consumer waste consists of wastes from the manufacturing and papermaking process as well as finished paper from obsolete inventories.

POSTCONSUMER WASTE

Post-consumer waste consists of paper, paperboard and fibrous waste from retail stores, offices and homes.

What Paper is Recycled?

Recycled Paper Sources

• Households -Newspaper -Mixed waste• Retail and wholesale -corrugated containers• Offices, Institutions, Printers and converters -High grade deinking

Recycled Paper Processing

• Sorting, Collection and Transportation• Storage• Re-pulping and Screening• Cleaning• Deinking• Refining, Bleaching and Color stripping• Paper making

Sorting, Collection and Transportation

Storage

Re-pulping and Screening

The paper moves by conveyor to a big vat called a pulper, which contains water and chemicals. The pulper chops the recovered paper into small pieces. Heating the mixture breaks the paper down more quickly into tiny strands of cellulose (organic plant material) called fibers. Eventually, the old paper turns into a mushy mixture called pulp.

Screening

The pulp is forced through screens containing holes and slots of various shapes and sizes. The screens remove small contaminants such as bits of plastic and globs of glue. This process is called screening.

Cleaning

Mills also clean pulp by spinning it around in large cone-shaped cylinders. Heavy contaminants like staples are thrown to the outside of the cone and fall through the bottom of the cylinder. Lighter contaminants collect in the center of the cone and are removed. This process is called cleaning.

Contaminant Removal• Metals• Chemicals• Thread • Plastic• Paper clips, Staples• Metal binders• Ink• Adhesives• Wax • Clay • solvent

Deinking• In the deinking stage, the goal is

to release and remove the hydrophobic contaminants from the recycled paper. The contaminants are mostly printing ink and stickies. Several processes are used, most commonly flotation or washing.

• Small particles of ink are rinsed from the pulp with water in a process called washing. Larger particles and stickies are removed with air bubbles in another process called flotation.

Flotation Deinking• The collector is added to the inlet of

the flotation. The process temperatures are normally in the range 45 - 55 °C. Air is blown into the pulp suspension. The collector has affinity both to the ink particles and air bubbles, causing them to attach. The air bubbles lift the ink to the surface and form a thick froth that can be removed. Normally the setup is a two stage system with 3, 4 or 5 flotation cells in series. Flotation deinking is very effective in removing ink particles larger than about 10 µm.

Washing Process

• Wash deinking consists of a washing stage where dispersants are added to wash out the printing inks. When the pulp slurry is dewatered (thickened), the medium to fine particles are washed out. This process is most useful for removing particles smaller than about 30 µm, like water-based inks, fillers, coating particles, fines and micro stickies.

Chemicals Used in Deinking

• Sodium hydroxide• Soap• Calcium salts• Surfactants• Hydrogen peroxide• Talc• Sulfuric acid• Solvents

Refining, Bleaching and Color Stripping

During refining, the pulp is beaten to make the recycled fibers swell, making them ideal for papermaking. If the pulp contains any large bundles of fibers, refining separates them into individual fibers. If the recovered paper is colored, color stripping chemicals remove the dyes from the paper.

Papermaking

The pulp is mixed with water and chemicals to make it 99.5% water. This watery pulp mixture enters the headbox, a giant metal box at the beginning of the paper machine, and then is sprayed in a continuous wide jet onto a huge flat wire screen which is moving very quickly through the paper machine.

The sheet, which now resembles paper, passes through a series of heated metal rollers which dry the paper. If coated paper is being made, a coating mixture can be applied near the end of the process, or in a separate process after the papermaking is completed. coating gives paper a smooth, glossy surface for printing.

Cont...

Finally, the finished paper is wound into a giant roll and removed from the paper machine. One roll can be as wide as 30 feet and weigh as much as 20 tons. The roll of paper is cut into smaller rolls, or sometimes into sheets, before being shipped to a converting plant where it will be printed or made into products such as envelopes, paper bags, or boxes.

Environmental Impact

• Effluent Processing• Sludge• Contaminant disposal• Refining, Bleaching and color Stripping

Benefits of Recycling Paper

• Recycling newspaper saves 14% of landfill space• Recycling one ton of paper can save 17 trees• Reduces sulfur dioxide emissions• Most paper can be recycled up to 8 times to

create new products• Leaves more trees for the sustainability of our

environment• Saves energy

Recycled paper uses• Paperboard• Folding box-board• Corrugated boxes• Egg cartons• Paper towels• Tissue• Toilet paper• Newspaper• Paper Bags• Notebooks• Calendars

References

• www.tappi.org• wikipedia.org• paperproject.org• Technology of paper recycling by R.W.J

McKinney