Swedish company Cemvision has announced a pioneering technology that transforms underutilised, low-value electric arc furnaces (EAF) and basic oxygen furnaces (BOF) slags into a high-performance supplementary cementitious material (SCM), while also recovering valuable metals.
Over 55m tonnes of steel slag are generated annually in the European Union, with 52 per cent of this volume currently underutilised and often landfilled at significant expense or, at best, directed to other low-value applications. While granulated blast furnace slag (GBS) has historically been crucial for decarbonising cement production, its availability is declining as EAFs and direct reduced iron (DRI) replace traditional blast furnaces. The US leads this industrial transformation, with 70 per cent of its steel production coming from EAFs. Europe follows at 30 per cent EAF production, a share that continues to grow as older blast furnaces are decommissioned. Yet, EAF slag remains underutilised mainly due to its chemical composition and high metal and impurity content.
Cemvision's patent-pending beneficiation process upcycles slag into a premium SCM. The performance of an SCM is typically measured in reactivity and glass content. Third-party testing of Cemvision’s SCM shows that it is on par with, or outperforms, ground granulated blast-furnace slag (GGBS) on both. EAF slag typically contains high amounts of iron oxide (25-40 per cent), of which 99 per cent can be extracted and recovered in the Cemvision slag valorisation process.
The iron can then be returned to steel producers and reintroduced into the steelmaking process, thereby completing a circular material loop and improving steelmaking efficiency. Other valuable elements in EAF slag such as chromium are also recoverable with the Cemvision slag valorisation process. The output material helps secure feedstock for both Cemvision’s Re-ment Massive and Rapid products, and can be used as a clinker-replacing SCM, ensuring and extending circularity in the cement industry.
Cemvision has successfully piloted this innovation with the world-leading metallurgical research institute, Swerim, proving both technical feasibility and commercial potential.
"This is a game-changer not only for the cement industry but for steel producers as well. Our process enables high-performing cement products from materials that would otherwise be treated as waste. With this innovation, we're proving that decarbonisation and circularity can go hand in hand, and at scale," says Oscar Hållén, CEO of Cemvision.
Dr. Elsayed Mousa, Senior Researcher in Metallurgy at Swerim, added: "Our trials with Cemvision show a clear pathway to industrialise this process. The chemistry and performance of the resulting materials are not only viable, they're promising enough to set a new benchmark for what green cement can be made from."
