The wood raw material contains the cellulose fibres that become pulp. The production process is based on separating these cellulose fibres from by-products. The by-products are then taken care of in a number of other cycles, one of which is energy. Even chemicals are recycled. Production is highly automated and almost everything is controlled and managed by computers.
The first thing that happens when pulp comes to the mill is that the bark is removed. It is collected and burned to create heating energy, sometimes after having been pressed into pellets. The wood that is stripped of its bark is chopped into chips. To separate the cellulose fibres in the wood, the chips are cooked. The cellulose is then washed and bleached. When the last unwanted by-products have been removed from the pulp, it is dried and cut into appropriately-sized sheets that are strapped together into bales for transporting on to paper mills.
The idea behind our softwood concept is wood segregation. Three kinds of raw material enter Södra’s woodyards; softwood thinnings, roundwood and sawmill chips. These different materials are mixed carefully to achieve different paper properties.
This is how we have designed our softwood product groups. Sawmill chips are the main component of green pulps, while our black range is predominantly thinnings and blue pulps are mainly roundwood.
Two of our mills, Södra Cell Värö and Södra Cell Mönsterås, use TCF (total chlorine free) bleaching sequences and the third, Södra Cell Mörrrum has an ECF (elementary chlorine free) bleaching sequence. This gives Södra the possibility to produce and sell both TCF and ECF products. TCF pulps have a Z in the product name.
A third component used in our branding is brightness, however all of our pulps are not fully bleached. Within all three groups we have pulp with 85 brightness and in the green group we also offer a pulp with 70 brightness.
A fourth factor is the drying method, either sheet or flash dried. Flash-dried pulp has the letter F in the name.