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The papermaking process can be split into several distinct stages.
1st stage.
Wood handling and preparation
The incoming spruce timber is processed to make wood chips and pulpwood. For wood chips, the timber is delivered directly to the debarking drums before transportation to the wood chippers. For pulpwood, the timber is sawn by slasher saws into 1.2 meter lengths (pulpwood) and then debarked. The pulpwood is transported to the Stone Ground Wood mill or to the intermediate storage pile.
2nd stage.
Semi-finished products (mechanical and thermo-mechanical wood pulp)
The debarked pulpwood is converted to pulp through mechanical grinding of wood in the stone grinders. The pulpwood is fed with water into the grinder magazines and is pressed lengthwise onto rotating ceramic stones, reducing the solid timber into fibres. The resulting wood pulp is screened, thickened and bleached.
In the Thermo-Mechanical Pulp (TMP) plant the wood chips undergo a cooking process and then are refined to pulp in a two-stage high-pressure process. The resulting thermo-mechanical wood pulp is also screened, cleaned, thickened and bleached.
3rd stage.
Paper production
The semi-finished products (TMP, mechanical wood pulp and purchased bleached sulphate chemical pulp) are delivered to the mixing vats where the paper stock for newsprint is prepared.
The paper stock is screened, cleaned and de-aerated before going to the paper machines. The wire part at the wet end of the paper machine forms the paper web. The web is de-watered under pressure exerted by press rolls and then runs through steam-heated drying cylinders, passes through calendar rolls that give the paper a smooth finish and then is wound onto a reel-up drum.
Finally, the paper is cut by a slitting machine into reels with the ordered dimensions. Wrapped and labelled on the packing line, the reels are then transported by conveyors to the warehouse for subsequent shipment by trucks, rail or ship to the end user. |