During the last couple of weeks an industrial test campaign using fly ash from a paper mill as a slag former in an electric arc furnace (EAF) has been successfully conducted at Outokumpu Stainless in Avesta. In the trials, 10% of primary lime was replaced with fly ash in more than 60 heats distributed over 10 different steel grades.

The main incentive for using the fly ash as a slag former is that a great share of CO₂ emissions can be avoided from the calcination of primary lime. This technique contributes to climate change mitigation, minimizing residues to landfill and saving natural resources.

“We are thrilled to have come to the stage of industrial testing”, says Jesper Janis, General manager Technical & Quality, from Outokumpu Avesta, “We are now looking forward to seeing these successful results leading to the implementation of using fly ash as future raw material in steelmaking, promoting the green transition through industrial symbiosis where one industry´s waste can be processed into the others raw material. This will further enable our circle green product, sustainable stainless steel, even more sustainable with lower carbon footprint.”

The fine fly ash powder from Essity was briquetted together with primary lime fines by SMA Mineral. The industrial campaign is a part of the Vinnova-funded challenge-driven innovation (CDI) OSMET 3.0 project (Dnr. 2020-04140) where this technique has been proven at a pilot scale in a 10-ton EAF at Swerim AB in Luleå.