Page 3: Recycling waste paper
Waste paper is the second vital source for the fibre used in making boxes. This reclaimed fibre is known as secondary fibre, to distinguish it from the primary fibre which is provided by wood. Both types of fibre are needed and on average, 70 to 80 percent of the fibre used in the production of a box is this secondary, recycled fibre. Virgin fibre from wood pulp is always required, however, because with each recycling, the cellulose fibres become shorter and less resilient. The Jefferson Smurfit Group is the largest recycler of paper products in the world, reclaiming some five million tonnes of waste paper each year through over sixty recycling centres worldwide. Waste paper is sorted, graded and baled before use.
Making the paper
To produce the paper used in making boxes, bales of wood pulp and recycled paper are placed into a pulper containing water and a powerful agitator. This agitator breaks up the pulp and mixes it with water to produce a porridge-like solution called stock. More water is added and the stock is refined and screened to remove impurities. The solution at this point is 99% water and only 1% fibre.
This solution is then passed over a very long conveyor of wire mesh, which allows much of the water to drain away, leaving only the wet fibres on top of its surface. This part of the process is known as the ‘wet end.’
The wet fibres are next passed through sets of heavy rollers where more moisture is squeezed out and drawn away. The wet paper fibres are then passed through a series of dryers, where steam-heated rollers evaporate the last of the remaining moisture before the paper is gathered up at the other end in long rolls. This part of the process is known as the ‘dry end.’
This entire process, from one end of the conveyor to the other, takes up as much length as a football pitch and it all happens extremely fast, with the paper fibre moving along through the conveyor at speeds of up to 2,000 metres per minute.
Paper mills require a very great deal of water to operate, which is why they are almost always located adjacent to a large source of fresh water, like a river. The water needed for the paper-making process must also be very clean and so filtering the water supply of impurities is an important part of the process. Nearly all of this water is recycled and returned to its source and, because of the highly efficient filtering process which the water must go through, the water returned at the end of the process is usually cleaner than it originally was.