“All wood raw material arriving at the site is utilised. Nothing is left unused.”
Johanna Harjula
Turpentine is used as a raw material for perfumes and on its own as a solvent, among other things. Tall oil can be used as a binding agent in products such as cleansers and glues. “In Rauma, the closest tall oil refinery is Forchem, operating next to Metsä Fibre’s Rauma mills. The company refines the tall oil into additives that can be used to replace fossil fuels. The additives can then be used in paints, coatings and printer ink,” says Ikonen.
The entire tree is put to use
At Metsä Fibre’s Rauma mills, the sawmill and pulp mill are located just a few hundred metres from each other. Their close proximity enables efficient synergies between the production plants. The Rauma sawmill focuses on producing dried sawn timber that meets the exacting standards needed for customer products in the component and carpentry industries. Pieces left over from production are turned into wood chips for the pulp mill. The bark and sawdust are used as sources of bioenergy. “All wood raw material arriving at the site is utilised. Nothing is left unused,” says Johanna Harjula , Mill Manager at Rauma sawmill. Fresh sawmill wood chips of consistent quality are excellent raw material for pulp production. “The chips travel from the sawmill along a conveyor without having to be loaded onto trucks. This is resource efficiency at its best,” says Jaakko Ikonen , Mill Manager at Rauma pulp mill.
We produce more electricity than we use
The pulp production process also generates a significant surplus of renewable energy. The Rauma pulp mill’s electricity self-sufficiency rate is 180 per cent. This means that the mill produces nearly twice as much electricity as it needs. Metsä Fibre’s most modern pulp mills have an even higher degree of energy self-sufficiency. For example, the Kemi bioproduct mill has an astounding 250 per cent self- sufficiency rate. The pulp mill uses some of the energy in its own processes, but there is plenty left over for other purposes as well. For example, the pulp mill supplies the sawmill with 100% of the electricity it needs, plus the heat energy to dry the sawn timber. Metsä Fibre’s operations are based on the sustainable use of raw materials and resource-efficient production. The company aims for all of its production facilities to be waste- free and fossil fuel-free by 2030. •
In 2023 the Finnish forest industry used 57.8 million cubic metres of domestic raw wood. 1 The wood used by industry is mainly harvested for logs or pulpwood. The classification into logs or pulpwood determines where the wood will be refined. In rough terms, logs are raw material for sawmills and pulpwood is raw material for pulp mills. “Thanks to collaboration between pulp and bioproduct mills and sawmills, Finland uses its forests as resource- efficiently as possible. The pulp industry refines pulpwood that, due to its small diameter, is not suitable for sawn timber production. The pulp industry also utilises byproducts from sawmills, that is, the parts of the trunk that cannot be refined into sawn timber,” says Jani Riissanen , SVP, Wood Trade and Forest Services at Metsä Group.
their natural development. The sapling stand is maintained after the regeneration of the forest. Next, one to three thinning cuts are made, followed by a regeneration cut at the end of the rotation period. Generally, only pulpwood is acquired from the first thinning. In regeneration felling, 70–90 per cent of the total felling volume can be logs. Logs and pulpwood are separated according to the diameter of the trunk and its quality. A sufficiently straight trunk section with a crown diameter of at least 15 centimetres is suitable for logs. Pulpwood consists of trees that do not fulfil the diameter and quality requirements for logs. Trunks with crooked growth or large branches may downgrade even a sturdy tree from the log category to the pulpwood category. Pulpwood is also acquired from thinning cuts and the tops of trees that reach the required height for logs. “The separation into logs and pulpwood starts at the harvesting stage. Harvesters know how to lay off and buck, i.e. cut the trunk so that it can be utilised as thoroughly as possible to maximise its value,” says Riissanen.
From pulpwood to pulp, bioenergy and other bioproducts
The wood chips used as raw material in the pulp process are rectangular and approximately 30–40 millimetres long. In addition to pulp, they consist of hemicellulose, lignin and extractive agents. The wood chips are boiled in a cooking chemical to dissolve the lignin and extractive agents that bind the fibres together. The fibres can then be restored as undamaged as possible. In the process, about half of the wood raw material is processed into pulp, which serves as the raw material for paperboard, tissue and printing paper and speciality products. The other half is used to produce other bioproducts, such as electricity, energy, turpentine and tall oil that can replace fossil- based raw materials in several end-uses.
The value is maximised during logging
In Finnish forestry, periodic cover forestry prevails. This means that forests are managed in repeated cycles that mimic
1 Official Statistics of Finland (OSF): Wood consumption [online publication]. Helsinki: Natural Resources Institute Finland.
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