German steel maker ThyssenKrupp announced that, after a three-month downtime and an investment in the mid double-digit million euros range, blast furnace Schwelgern 1 in Duisburg in Germany resumed production on October 1 to produce around 10,000 tonnes of hot metal per day. After the completed upgrade of the blast furnace, thyssenkrupp Steel can again operate at full hot metal capacity. With a maximum annual capacity of 3.6 million tonnes of hot metal, Schwelgern 1 is one of the largest blast furnaces in the world.Relined and equipped with state of the art technology, thyssenkrupp Steel Europe’s blast furnace Schwelgern 1 had continuously been in operation for over 13 years, before the 48 year-old colossus was taken out of service for relining on July 7.The blast furnace was relined, among other things, enabling it to withstand the extreme temperatures of around 2,000 degrees for many years. The so-called partial relining will have been one of the last in the history of thyssenkrupp Steel Europe, as the Duisburg-based steel mill is on its way to climate-neutral steel production. To this end, the company will gradually replace its four conventional blast furnaces at the Duisburg site from 2025 with climate-friendly direct reduction plants which will be operated with green hydrogen instead of coking coal in the long run. Since 2020, the giant has already been emitting less carbon dioxide than before owing to an innovative technology involving the injection of additional oxygen.