The second step of paper production: From chips to pulp
How paper is made - the step from pulp to chips. Animated with English voiceover. Open video on YouTube.
From wood chips to pulp
The TMP refiner, which is like a high-tech version of an old coffee-grinder, is the heart of this phase. The chips are transported from the storage silos, passing through a water washing process, and then heated with steam to soften the lignin, which is the glue which holds wood fibres together. The uniform, heated chips are then fed into the TMP refiner using a high-pressure screw feeder.
The TMP refiner consists of two stages where two giant metal grinding plates, one stator and one rotor, with intricate grooved patterns are rotating at approximately 1500 RPM. The gap between the plates is only 0.6 mm, thereby shredding the chips into papermaking fibres while the intricate patterns ensure that the fibres are separated in the lengthwise direction instead of being cut into dust. The aim is to produce long straight fibres that are slightly brushed on the surface to produce what is called micro-fibrillation, but without cutting them up into short fragments.
The combination of woodchips, water, steam, and energy going through the tiny 0.6 mm refiner plate gap generates high-temperature and high-pressure steam, which is recovered as described on the introduction page.
The pulp, or papermaking fibres, are now screened to make sure they are all separated from each other and then bleached to get an acceptable level of brightness.
TMP fibres are much stiffer than many other grades of pulp, which give key benefits to the paper sheet. For example, they provide paper used for books with high bulk and high stiffness properties, resulting in a high-quality comfortable feel for the user.
In the next step, you will see how to go from pulp to paper.
The papermaking process
Step 1: From logs to chips
The pulpwood enters the mill and is washed, debarked, cut and chipped before moving on to the pulping step.
From logs to chipsStep 2: From chips to pulp
The wood chips are steamed, refined, relaxed and bleached before entering the paper machine.
From chips to pulpStep 3: From pulp to paper
The paper pulp enters the paper machine and exits as a finished sheet of paper after just 15 seconds.
From pulp to paper