Paper-Recycling System: Part 5

The furnish profile in Central Europe was somewhat different from the furnish profile in Scandinavia. Reuse pulp was clearly used more in Central European production. For liner board and fluting, reuse pulp had a share of about 70% in Central Europe, while in Scandinavia the share was only about 5%. Reuse pulp was used in about 25% of the newsprint in Central Europe, but was hardly used at all in Scandinavia. For soft paper qualities, reuse pulp was used almost equally in both areas, about 35%. Mechanical pulp was more widely used in Scandinavian production, and semi-chemical pulp was nearly only used in Scandinavia.

Reuse pulp is produced in two types of plants. For less-demanding paper qualities, the waste paper recycled is treated in mechanical re-pulping plants. The pulp is not chemically de-inked and is typically used for brown papers and boards, for bobbins, egg containers, and so on. For higher-quality products, the waste paper is re-pulped, chemically cleaned from pigments, and sometimes also bleached. De-inked recycled pulp is typically used for newsprint and soft papers.

Generally, mechanical re-pulping for low-quality papers constitutes the following steps:

1. Waste paper feed and pulping
2. Pre-cleaning (mechanical)
3. Refining
4. Final cleaning (mechanical)
5. Thickening and storing
6. Drying and packaging (only for market pulp)

Pulping (1) is done with either batch or continuous pulpers. Caustic soda and aluminum sulfate are used for pH adjustment and dispersion agents, such as derivatives of glycol ether. Pale wires and larger plastic particles are removed with ragger. In pre-cleaning (2), solid impurities such as plastic flakes are extracted from the pulp with centrifuges and pressure sorters. In the refining step (3), pulp undergoes washing, sorting, and milling. After this step, refining pulp is again cleaned mechanically (4) and thickened (5) for storage. Market pulp is dried and packed for transportation, step (6).