Sawmills and pulp mills support each other

In Finland, the main uses for wood are as logs for sawmills or as pulpwood for pulp mills.

People sometimes ask whether Finnish forestry and forest-based industries should concentrate on sawing timber instead of pulping wood.

In fact, there is a benefit in having both sawmills and pulp mills.

When mechanical and pulping industries work side by side, forests are used in the most resource-efficient way possible.

Jani Riissanen, Metsä Group's Senior Vice President, Wood Trade and Forest Services

“The pulp industry uses by-products from the sawmill industry and also pulpwood that is not suitable for sawmill production because it’s too small in diameter. When mechanical and pulping industries work side by side, forests are used in the most resource-efficient way possible,” says Jani Riissanen, Metsä Group's Senior Vice President, Wood Trade and Forest Services. 

Maximizing the value of wood

During the rotation period, a forest stand is thinned one to three times, before a regeneration felling at the end of the period. The first thinning yields trees that are suitable only as pulpwood. In regeneration felling, the share of logs in the total felling volume can be as high as 90 per cent in southern Finland and around 70 per cent in the north.

Sawmills need a sufficiently straight trunk section with a minimum diameter of 15 centimetres. It must be free of large branches and rot.

“The separation into logs and pulpwood starts at the harvesting stage. Logging machines know how to lay off and buck, i.e. cut the trunk so that it can be utilised as completely as possible to maximise its value,” says Riissanen.

In the timber trade based on wood assortments, forest owners are paid different prices for pulpwood and sawlogs. Alongside the traditional trading method, Metsä Group has introduced what is known as the stem volume method. In this approach, trees are purchased as whole stems, and the process of converting stems into logs and pulp does not impact the forest owner’s revenue from wood sales.

Thanks to this new pricing method, the wood can be cut into pieces that suit current demand and market conditions. This helps optimize the processing value of the wood in all final product market situations.

The entire tree is put to use

In Metsä Fibre's Rauma integrated mill, all timber is put to use. The logs arriving at the sawmill are processed into boards, planks, and other sawn timber products.

“Nothing is left unused. Any wood that is not sawn into timber is chipped for pulp mills. The bark and sawdust are used for energy," says Johanna Harjula, Mill Manager of Metsä Fibre’s Rauma sawmill.  

In Rauma, the sawmill and pulp mill are located next to each other, which further enhances synergies.

"We send the wood chips to the pulp mill, which in turn provides us with renewable electricity and heat for drying sawn timber. It’s a perfect circular economy.”

Mill Manager Janne Rantanen of Metsä Fibre’s Rauma pulp mill is also pleased with the synergy.

“The chips travel from the sawmill along a conveyor without having to be loaded onto trucks. This is resource efficiency at its best,” he says.

From pulpwood to energy and bioproducts

In a pulp mill, wood chips are cooked in a cooking chemical to release the lignin that binds the fibres together. In the process, about half of the wood raw material is processed into pulp, i.e. raw material for paperboard, tissue and printing paper and speciality products.

“The other half is processed into various bioproducts, including turpentine and pine oil. The by-product of the pulp process also generates renewable energy that is well in excess of the mill's own needs,” says Rantanen.

Metsä Fibre's operations are based on the sustainable use of raw materials and resource-efficient production. The company's target is that all its production facilities will be waste-free and fossil fuel-free by 2030.