Making paper paste

Paper, cardboard, or food-packaging (bricks) are an important source of recyclable material that can be used by the paper industry to make new products. These materials can be separated into three families (the paper sorting cycle) that will undergo different levels of recycling: paper for packaging (mainly brown paper), paper for newspapers and magazines, and white paper for specific uses (sanitary, printing and writing paper, white wrapping paper…). Organising the collection, the flow, and the sorting of paper and cardboard ahead of the recycling process at the factory, in other words all of Paprec’s paper recycling skills, is an important requirement for the success of our clients in the paper making industry. Here are the main steps of the process.


 The first step for making new paper paste is the fibre suspension. Bales of paper waste are triturated in a pulper, to suspend the fibres in water. This machine is like a giant mixer. The fibres are crushed to a pulp state, to then be transported to pumps.
By nature, recycled paper (and because of the different storage processes) contains many elements that need to be removed, such as glue, tape, metals, staples, string, ink, binding. The methods used to eliminate them are simple.
This separation, an essential part of the paper paste making process, can be achieved by filtration. The diluted fibres go through several increasingly small sieves. Starting with a 5mm filter (eliminating plastics and bindings), the filtering goes all the way down to 120 microns, at which stage only the fibres can pass.
Separation can also be achieved by density filtration. This is particularly practical to filter out heavier elements such as staples or paper clips. This method is also used in more sophisticated machinery, such as the ones used to removed varnished ink.
Water can also be used as a filtration process. Most of the ink used is oil-based, and therefore could be easily separated from the paper by using its water-phobic characteristics.
With the fibre suspension has undergone all these filtration processes, the whole process is repeated, after a thorough draining and an extra pass through the pulper. Today, the water is recycled and reused up to four times.
The final step is the bleaching process, increasing the pulp’s whiteness, and decreasing the saturation of coloured paper. This process uses only hydrogen peroxide and sodium hydrosulphite, with low environmental impact.
Our clients are now capable of making quality pulp with recycled paper, as good as wood pulp, using less energy, less water, and a lower environmental impact.
Nevertheless, it is important to note that paper and cardboard can not be infinitely recycled.
Each time paper is made and recycled, the quality of the fibres lessens. It is estimated that the same fibres can be reused 5 to 7 times, depending on the desired quality.
But to reach that limit, 80% of paper material would have to be recycled. We are still a long way away from that ratio, because not all types of paper are recycled (sanitary paper, food packaging). It is therefore necessary to mix the recycled paper with new pulp.


At the deinking sites, the sorted and eliminated waste is sent to the appropriate recycling channels.
Metal (staples, paper clips) is sent to the scrap metal factories.
Chalk and clay mud goes to the construction sector (cement, tiling, bricks…).
Plastic, if homogenous, is reused.
Other various mixed waste is sent to incineration for energy recuperation. 
The paper and cardboard recycling cycle is a step-by-step process. Discover the different steps:


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