ArcelorMittal’s Hamburg steelworks 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.
The company invested two years of development in the new process, and now around half of the coal previously used in the EAF is being replaced by an alternative that conserves resources. The process saves 3,500 tonnes/year of direct CO2 emissions, Kallanish hears from the company.
At the beginning of the project, ArcelorMittal engineers tested various substitutes for their suitability together with technology supplier Stein Injection Technology. “Among other things, we examined sewage sludge and paper fibre residues, processed orange peel and non-recyclable waste,” says project manager Michel Wurlitzer.
The most convincing results were delivered by a residual material granulate from waste from private households and similar institutions. The CO2 reduction is made possible by the biogenic carbons contained, which are present in paper or cotton fibres, for example, and by the hydrogen contained. Another advantage is that the high temperatures in the steel bath, which exceed 1,600 degrees Celsius, lead to the complete decomposition of the granulate.
Christian Koehl Germany