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Paper Recycling Process

Thứ tư - 03/07/2013 19:18

1. Sorting:
In order to have successful recycle process, the material need to be sorted carefully to sure that paper material is not included impurities and contaminants such as food scraps, plastic, metal and many others ... because they make it difficult recycling of paper. Paper with too much dirt, impurities cannot be recycled.

2. Pulping and screening:
The recycled material is taken to a large tank, which contains water and chemicals. In this process, recovered paper will be cut into small pieces. The heated mixture will make old paper to be quickly cut into many pieces of cellulose fibers. Recovered paper will be dedicated to become a mixture called "pulp".
Pulp will be pushed to the screen with the holes and grooves of all shapes and sizes; in which small pieces of impurities such as nylon tape will be retained. This process is called "screening".

3. Grinding:
Pulp will be cleaned in the conical tube by shaking motion, the heavy impurities such as metal clamps, pins will be knocked off the hat and hit the bottom of the tube. Light impurities will be collected in the middle cone and removed. This process is called "grinding".

4. Inks removing:
The pulp must be go through a process of "washing" to remove the ink and tape (including glues paste and tape). Small ink particles are removed by water in the process called "discharge". The larger particles and adhesive tape will be sent to the same types of bubbles in a process called "flotation".
In the flotation process, starch is stored in large tanks of air and soap-like chemicals called surface-active substances. Surface-active substances will separate ink and adhesive tape from the dough, push them to the surface by the bubble mixture. The bubbles make ink forming foam or sparkling dark layer above and leave a pulp "clean" below.

5. Refining, Color Stripping and Bleaching
During refining, the pulp is beaten to make the recycled fibers swell as well as to separate the individual fibers to facilitate paper making.
If the recovered material is colored, color stripping chemicals are added to remove the dyes. From this processing, brown paper is obtained.
If white recycled paper is produced, the pulp would need to be bleached with hydrogen peroxide, chlorine dioxide, or oxygen to make it whiter and brighter.

6. Paper making:
At this step, we have "clean pulp" which is ready for making new products. Recycled fibers which have been able to use its own, or mixed with wood fiber (called primary fiber) to increase smoothness and durability. The pulp is mixed with water and chemical to achieve mixture of 99.5% water. This mixture then enters the head box of a paper making machine and is sprayed in a continuous jet onto a huge wire mesh-like screen moving very quickly through the paper machine.
On the screen, water starts to drain from the pulp, and the recycled fibers begin to bond together to form a watery sheet. The sheet then moves rapidly through a series of felt-covered press rollers which squeeze out more water from the pulp.
Paper, when wet - now looks like a normal paper - will be given through a series of metal rollers were heated to dry the paper. If you want something coated, paper coating mixture will be taken at the end of the cycle or in another process after the paper has been done. The coating is intended to be for the paper has a glossy smooth surface, easy to print.
Finally, the finished paper products will be rolled into a big roll and left machine. The roll can be up to 9-10 m wide and the weight is almost 20 tons! Finished roll can be cut into smaller rolls or sheets for transporting to the factory in which they will be printed or processed into products such as envelopes, bags or barrel boxes...
In this way, recycled paper is created!!!!

More information:
Paper cannot be recycled forever.
After some recycling times, they have to move to landfills or incinerators. Therefore, the most importance is using paper economically and efficiently to protect our environment.

Author: Elly Hoa - Vietnam Poly Bag Import Export JSC

Source: www.sooperarticles.com

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