Ovako’s steel production is based entirely on the recycling of steel scrap. This makes Ovako the largest recycler of steel scrap in the Nordic region and an important participant in the circular economy. Steel manufacturing also generates significant quantities of residuals, and Ovako conducts extensive development work to ensure these are used where they bring the most benefit to society.
Residuals are handled differently, depending on whether they are classified as by-products or waste. By-products, for example, need to be registered and assessed in accordance with the European chemicals regulation (REACH), which deals with registration, evaluation, authorization and restriction of chemicals. Ovako’s by-products covered by the regulation are arc furnace slag from the three smelters, scale from the group’s rolling mills and forging operations, and oxygen scarfing granulates and iron sulfate from Hofors. Another by-product from Hofors is olivine sand, but this material is not registered because it is covered by an exemption in the regulation.
How other residuals from Ovako’s facilities are managed varies depending on the relevant assessment. Residual products that are currently managed as waste include filter dust from the three arc furnaces, ladle furnace slag from the ladle processes and bricks from various types of furnaces or from casting operations.
Arc furnace slag is an excellent construction material. In addition to its use in concrete, it is especially suitable as aggregates in asphalt where it replaces crushed natural rock. The slag attracts the bitumen binder in the asphalt, causing the pieces of slag to remain in place and making the asphalt last longer. Asphalt made from slag also has noise-reducing properties and is less affected by temperature changes than standard asphalt.
Slag from some of Ovako’s mills can be bought as CE-marked asphalt aggregates, and in Smedjebacken a long-term contract has been concluded for delivery of slag to a major Swedish asphalt producer.
Ovako is currently involved in the MinRent research project, financed by Vinnova, which is testing slags in water treatment applications. Iron sulfate from Ovako in Hofors is also used as a chemical for water purification and as an additive in cement production. Metallurgical slags from the arc and ladle furnaces also contribute to drastically to reduced CO2 emissions when used as an input material in cement production.
Scale and oxygen scarfing granulates are iron oxide based by-products that can be used as raw materials in the production of iron and ferroalloys, and in the manufacture of cement or heavy concrete. The materials can also be used as ballast in loose form. For example, the full-rigged ship Af Chapman beside Skeppsholmen in Stockholm is ballasted with 738 tons of scale from Ovako in Smedjebacken.
Bricks used for furnaces and casting systems can be largely recycled and become raw materials for similar new applications. Olivine sand can be used in refractory applications and in mineral wool production. Similarly, zinc from galvanized scrap can be recovered from the filter dust from Ovako’s arc furnaces.