The first next-generation bioproduct mill in the world
When the Finnish forest industry group Metsä Group constructed a new bioproduct mill in Äänekoski, Central Finland, precast concrete elements played an important part in making sure that the tight schedules were met.
The massive mill project required thousands of precast concrete elements – made from more than 31,500 metric tons of concrete.
The Äänekoski mill is the first next-generation bioproduct mill in the world. In addition to high-quality pulp, it produces a broad range of bioproducts, such as tall oil and turpentine, bioelectricity, and wood fuel. Other potential bioproducts created from production side streams include textile fibres and lignin products, for example. Totaling EUR 1.2 billion, the investment in Metsä Group’s bioproduct mill is the largest in the history of the Finnish forest industry.
Speed of construction was one of the primary benefits of using precast concrete elements in the frames of the mill buildings. But Samu Ristolainen, the project’s main structural engineer, does not hesitate to cite other reasons: adaptability, strength, durability, and fire safety.
The massive size of the mill structures and the special requirements of a bioproduct mill tested the limits of concrete element production. The mill’s barking plant building posed the biggest challenges with its 45-meter long primary braces, which were at the limits of what prestressed concrete can do. Also the framework of the causticizing plant was demanding to build. It required massive pillars to support the weight of the lime silo located on the building roof.
Despite the challenges, the schedules stayed on target: excavation work in the mill area began in the spring of 2015, and test use will commence a mere two years later, in the spring of 2017.
Most of the mill’s precast concrete elements were supplied by six different factories of Parma, the largest precast concrete element manufacturer in Finland. Parma belongs to Consolis Group, the largest precast concrete solution provider in Europe, which operates in 30 countries.
Sweco Industry Oy and Sweco Rakennetekniikka Oy were responsible for the detailed engineering of the mill. Sweco is Europe’s leading architecture and engineering consultancy.
Metsä Group’s bioproduct mill in figures
Gross building area: 142,000 m2
Total building volume: 1,200,000 m3
In-situ concrete: 100,000 m3
Load-bearing concrete arches: 80,000 m2
Steel structures: 7,000 t
Concrete elements: 15,000 pcs