Saint-Gobain’s slag processing plant promotes the circular economy in the construction industry

Saint-Gobain and SSAB are building a circular economy process that will turn side streams from SSAB’s steelmaking into low-carbon binders for Saint-Gobain Weber’s dry mortars. A slag processing plant, where high-value binders to replace cements will be made from slag created in steelmaking, will complete in Raahe in 2025. The process means the carbon footprint of binders is as much as 90% less compared to traditional cements.

The process is the first of its kind in the world and will enable 100% of the slag created in SSAB’s steelmaking process to be recycled. Saint-Gobain and SSAB have been developing the process together for five years.

“When we studied SSAB’s manufacturing process, we noticed that the end step in the processing of special steel has similarities to the production of special cement. We can replace the slag created as a side stream of steel cleaning to replace, for example, the special cement used in Weber dry mortars,” says Gunnar Lauren, Senior R&D Manager at Saint-Gobain Finland.

The slag processing plant is a resource-efficient, circular economy project, which will enable raw materials in the steel industry to be used as efficiently as possible. The new plant will sort slag, and separate metals that can be returned as raw materials to SSAB’s production process. These metals account for around two thirds of the material. The remaining material will be turned into alternative binders for the use of Saint-Gobain. This means that all the slag will be used and no waste will be produced in the process.

“This project supports our ambition to be a leader in responsible steelmaking. SSAB has taken a policy decision to transform all its production sites to fossil-free steelmaking. Already at this stage, it is important to ensure that also future by-products are utilized as efficiently as possible and this project is a part of this development,” says Marko Mäkikyrö, Director, By-product sales and development at SSAB.

Processing plant being built in Raahe Harbor area receives Programme for Sustainable Growth funding

Saint-Gobain is investing around EUR 12 million in the slag processing plant and processes. The investment supports Saint-Gobain’s ambition to achieve net zero carbon emissions in Finland by 2025 and globally by 2050. SSAB’s investment is around EUR 2 million. Saint-Gobain and SSAB’s joint project has been awarded funding of around 35% from the Sustainable Growth Programme for Finland under NextGeneration EU funding.

“The process will enable us to reduce more than 20,000 tonnes of carbon dioxide emissions a year. The use of virgin materials will decrease and the use of domestically manufactured raw materials increase,” says Gunnar Lauren, Senior R&D Manager at Saint-Gobain Finland.

Saint-Gobain filed a patent for the use of slag powder as a binder in 2022.