Residual granulate instead of coal

Gewöhnlicher Hausmüll lieferte die besten Ergebnisse. © ArcelorMittal

Turning waste into raw material – ArcelorMittal’s Hamburg steel mill has recently started using a granulate made from municipal waste instead of coal to produce crude steel from sponge iron and recycled scrap in an electric arc furnace. In turn, crude steel is the basis for the production of a wide variety of steels ranging from reinforcing steel in the construction sector to wire for nails, screws, fences and springs, and steel cables that provide support for drilling rigs, ski lifts and bridges.

ArcelorMittal Hamburg invested two years in the development of the new process, and now around half of the coal previously used in the electric arc furnace is being replaced by a more resource-efficient alternative. “With this project, we are now saving 3,500 tons of direct CO2 emissions per year,” says project manager Dr.-Ing. Michel Wurlitzer.

At the start of the project, ArcelorMittal engineers worked with Stein Injection Technology GmbH from Gevelsberg in the Ruhr region, a technology supplier, to test various substitutes for their suitability. “Among other things, we tested sewage sludge and paper fiber residues, processed orange peels and non-recyclable waste. Our colleagues at Stein Injection Technology supported us with their injection technology to guarantee the eligibility of the test materials,” explains Wurlitzer.

The most convincing results were obtained with a residual granulate from waste from private households and similar establishments. The CO2 reduction is made possible by the biogenic carbons present in paper or cotton fibers, for example, and by the hydrogen they contain. Another advantage is that the high temperatures in the steel bath, which exceed 1600 degrees Celsius, lead to complete decomposition of the granules. Says Wurlitzer, “Our emissions tests show that the use of the substitute produces no measurable pollutant emissions.”
ArcelorMittal Hamburg Managing Director Dr. Uwe Braun is pleased to see so much commitment in his own company. “Decarbonization of steel production is one of the most important cornerstones for achieving climate targets in Europe.”