The entire tree is used – nothing goes to waste

“Precise and efficient logging is a prerequisite for the optimal use of trees,” says Harri Haapaniemi, VP, Production, Timber and Upgrades at Metsä Fibre.

The harvested trees are cut in the forest in accordance with instructions from sawmills, and the sections are divided into three piles. One of the piles is for timber logs for sawmills, plywood mills and Kerto® LVL mills. Another one is for thinner trunks – that is, pulpwood. The third pile is for branches.

“This clear division ensures that 100 per cent of each trunk can be used, and it also ensures the best possible added value, beginning in the forest,” says Niklas von Weymarn, CEO of Metsä Spring.

Metsä Fibre’s Vilppula sawmill is one of the most modern sawmills in the world. Its state-of-the-art technology enables highly efficient and flexible production.

At sawmills, each log is measured, optimised and sawn precisely for the manufacture of products. The Vilppula sawmill uses 3D meters to measure the dimensions and shape of logs, and the insides of logs are studied using optimising X-ray devices. These indicate what products the logs are best suitable for and in which direction they should be sawn to ensure the optimal use of the valuable raw material.

“Vilppula’s competitive advantages include an optimising saw line where the process can be tailored to each individual log,” says Harri Haapaniemi. The optimising saw line captures several images of each tree and quickly turns the log into individually sawn pieces of timber.

“The smart saw line continuously optimises its operations. The saw line checks whether the product is being manufactured as it should be or whether the sawing process should be re-customised to ensure that no raw material is wasted,” Haapaniemi adds.

The entire trunk is used at the sawmill
During an ordinary working day, 100 truckloads of logs are delivered to the Vilppula sawmill, where the timber logs are converted into 45 truckloads of sawn timber. In addition, the sawmill produces 25 truckloads of wood chips for pulp production, 14 truckloads of sawdust for the pellet mill on the same site, and 11 truckloads of bark for the production of renewable energy at the sawmill’s biopower plant.

“Each production side stream is used effectively and entirely, down to the last chip of wood and grain of sawdust,” Haapaniemi explains.

At Metsä Group’s pulp processes, the valuable wood raw material, as well as the production side streams, are used effectively for bioproducts and renewable energy, at a rate of nearly 100 per cent.

The core of the bioproduct mill is an energy-efficient pulp mill that manufacture high-quality pulp as the primary products. “Around half of the wood delivered to the mill goes to pulp in the end and side streams represent the other half. Over the decades, industry has learned to make effective use of these fractions,” says Niklas von Weymarn.

The manufacture of new bioproducts is a key part of the bioproduct mills operations. Various by-products are generated during pulp production, including tall oil, turpentine and various forms of renewable energy.

The bioproduct mills of the future will not produce any waste at all
The goal is for bioproduct mills to produce no waste at all – not even a gram. Instead, all of the materials are used where their use is most beneficial. The new bioproduct mill in Äänekoski is a role model in this respect.

Metsä Group produces renewable energy from the bioproduct mills’ side streams, bark and sawdust from sawmills, and forest harvesting waste, such as branches and crowns. Bioproduct mills use these materials to produce electricity and heat, for example.

“The rule of thumb is that the valuable wood raw material is always used where it’s most beneficial. Each part of the tree, as well as pulp production side streams, is primarily used as raw material for products. Production waste that is not suitable for the production of materials is used for renewable energy,” says Ilkka Latvala, SVP, Energy at Metsä Group.

Renewable energy from wood-based sludge
The bioproduct mill in Äänekoski is a prime example of a sustainable, integrated mill that is able to use and recycle nearly 100 per cent of its side streams. For example, sludge generated during pulp production is used for energy.

“Sludge used to be disposed of, but now it’s directed to our mill through pipes, and we use it to produce biogas and biopellets. This shows how waste can be a valuable raw material – and we are making effective use of it,” says Tero Mäki, Managing Director of EcoEnergy SF, which recently joined the industrial ecosystem in Äänekoski.