Turning waste into raw material: At ArcelorMittal’s Hamburg steel mill, a granulate from municipal waste is used instead of coal to produce crude steel from sponge iron and recycled scrap in an electric arc furnace. The crude steel, in turn, is the basis for the production of various steels ranging from reinforcing steel in the construction sector to wire for nails, screws, fences and springs to steel cables that give support to oil rigs, ski lifts and bridges.
Two years of development were invested in the new process at ArcelorMittal Hamburg, and now around half of the coal previously used in the electric arc furnace is being replaced by a more resource-efficient alternative.
“We are saving 3,500 metric tons of direct CO₂ emissions a year from now on with this project”,
says project manager Dr.-Ing. Michel Wurlitzer.
At the start of the project, engineers from ArcelorMittal 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 examined sewage sludge and paper fiber residues, processed orange peel and non-recyclable waste. Our colleagues at Stein Injection Technology assisted us with their injection technology to guarantee the eligibility of the test materials,”
The most convincing results were delivered by a residual material granulate from waste from private households and similar facilities. The CO₂ reduction is made possible by the biogenic carbons it contains, which are present in paper or cotton fibers, for example, and by the hydrogen it contains. Another advantage is the high temperatures in the steel bath, which exceed 1600 degrees Celsius. These lead to complete decomposition of the granules. Wurlitzer:
“Our exhaust gas tests show that the use of the substitute does not produce any measurable emissions.”
ArcelorMittal Hamburg Managing Director Dr. Uwe Braun is pleased to see so much commitment in-house:
“Decarbonizing steel production is one of the most important cornerstones for achieving climate targets in Europe.”