In 2017, Metsä Fibre and ANDRITZ Oy participated in the LigniOx project coordinated by VTT Technical Research Centre of Finland. The project was part of the EU’s Horizon 2020 programme and the aim of it was to create technology for lignin-based products and to create the prerequisites for the launch of commercial production.
During the four-year project, it was demonstrated that it is possible to refine a bioproduct from lignin separated from the pulp process. This bioproduct could then be used for example as a concrete plasticiser.
After the project, the collaboration between Metsä Fibre and ANDRITZ continued in both process and product development and led up to the decision to build a demo plant for the refined lignin product on Metsä Group’s Äänekoski mill site.
Anna Suurnäkki, VP Research at Metsä Fibre, sees the LigniOx project as an example of a successful joint project.
“This is exactly how collaboration projects should work. They create a good value chain to continue corporate collaboration.”
Construction of the lignin product demo plant will begin in the summer of 2024, and test run will begin in 2025.
A bio-based alternative to replace synthetic concrete plasticisers
Lignin is a natural biopolymer which can be found in the cell walls of plants. In the pulp process, lignin is separated from the fibres chemically. It remains in the black liquor that is formed during the process.
The black liquor is then transferred from the bioproduct mill’s evaporation plant to the demo plant. The lignin is precipitated from black liquor using carbon dioxide, after which it is further processed with alkali and oxygen. The end product is finalised during post-treatment. The fractions left over from the separation are put back into the chemical cycle of the bioproduct mill.
According to Suurnäkki, one application for the new lignin product is as a bio-dispersant plasticiser. A plasticiser is an additive that improves the pumpability of concrete. The global market for concrete plasticiser is several million tonnes annually. However, the plasticisers now used are mainly synthetic products.
“We believe that our new lignin product has potential. With the demo plant, we can offer test batches that help us assess the market’s interest in the product.”