Metsä Fibre is renewing its mills in line with a unique bioproduct mill concept that takes resource efficiency and sustainability to an entirely new level. The concept combines efficient raw material use with energy and environmental efficiency.
Äänekoski bioproduct mill, which started up in 2017, was the first mill to adopt the concept. Kaija Pehu-Lehtonen, SVP, Business Development of Metsä Fibre, says the concept was found to work well in Äänekoski and is now being introduced and refined in Kemi.
“You always learn new things along the way, and we build on them in subsequent projects. The new Kemi mill is even more advanced in energy, resource, and environmental efficiency,” she says.
The bioproduct mill concept is based on the concept of using the wood raw material and production side streams 100 per cent in the form of bioproducts that can replace fossil materials and fuels. As well as producing 1.5 million tonnes of softwood and hardwood pulp every year, Kemi bioproduct mill makes tall oil, turpentine and bioenergy. The process also generates product gas and sulphuric acid, which can be used in production.
World-class technique is used to minimise the environmental impact of operations.
Best available technique
Pekka Kittilä, Technical Director of the Kemi mill project, points out that continuous improvement is an integral element in Metsä Fibre’s mode of operations.
Kemi mill is being constructed with the best available technique (BAT) and in some cases, using even more advanced technique. The mill meets the requirements in the EU’s relevant reference documents (BREF).
World-class techniques helps minimise the environmental impact from operations. Product gas made from tree bark replaces fossil fuel in the lime kiln. The mill is on target to achieve extremely low water consumption. Water intake is lower than that of the current Kemi pulp mill, even though production will increase 2.5-fold.
In pulp mills, excess heat from production has usually been dispersed into waterbodies, but Kemi has a closed cooling water cycle, which holds water consumption at an extremely low level. Another example of its advanced technique is the in-house sulphuric acid plant, which will use sulphur compounds from the mill’s odorous gases, reducing sulphate emissions.
“In practice, around half the sulphuric acid required by the mill will be produced from the mill’s own odorous gases. The production of sulphuric acid is a major step towards a more closed chemicals cycle,” says Kittilä.
The mill’s own sulphuric acid plant will reduce the volume of purchased chemicals.
“The gasification of wood bark and production of sulphuric acid are good examples of technique that is more advanced than BAT requirements. The wastewater treatment plant at the integrated mill will also achieve emissions levels lower than those in BAT requirements.”
Data is collected throughout the production process.
Simulation guarantees quality
Efficient, steady and sustainable pulp production, providing premium pulp for a range of customer needs, is a key element of Metsä Fibre’s bioproduct mill concept.
Matti Toivonen, SVP, Technology at Metsä Fibre, points to Kemi’s goal to use the best available technque to produce better pulp with improved quality consistency.
The data collected from the production process and its use play an important role in production efficiency and product quality.
“We collect data throughout the production process, starting at the woodyard. We then use this data to anticipate potential disturbances and further improve the reliability of mill operations. This helps us guarantee the premium quality of products,” he says.
A variety of modelling tools is used to assist the simulation of production processes, the optimisation of water consumption, the running of various alternatives and the assessment of their impact on the quality of end products.
Development work will continue in Kemi after the mill’s start-up in accordance with the principles of continuous improvement.
“We will tweak new processes and fix any defects observed. The mill’s good performance is a combination of advanced technique and the employees’ expertise and competence,” says Kittilä.
Power from the ecosystem
During the Äänekoski project, Metsä Fibre gained valuable experience in the construction of an ecosystem and partner network around the bioproduct mill. The new mill will lay the foundation for a growing industrial ecosystem in Kemi, based on new bioproducts and partnerships. The development of new bioproducts is a collaborative effort involving various experts in the value chain.
“The idea is to efficiently use production side streams in new bioproducts that generate the greatest possible added value. We do not try to do everything ourselves. We want to create a company network around the bioproduct mill, where everyone focuses on their core competence and helps promote the bio- and circular economy,” says Pehu-Lehtonen.
Äänekoski offers several examples of partners using pulp or pulp production side streams as raw material for a variety of new bioproducts. These include Kuura textile fibres, a 3D fibre product for the packaging industry called Muoto®, as well as a biomethanol refinery under construction.
“Similar products may also be produced in Kemi. We are always on the lookout for new bioproducts. We are researching topics such as lignin conversion and the use of green liquor dregs in geopolymers.”
Through its high-quality sustainable pulp production, as well as their accompanying emerging innovations and partnerships, the bioproduct mill will secure the future of Metsä Fibre and the entire Kemi region for many decades to come.
“Sustainability and fossil-free products and operations have quickly become increasingly important to our customers, and we can now meet their expectations ever more effectively.”
This article was originally published in Fibre Magazine issue 2022–2023.