Steel made from plastics. Projects in the steelmaking industry
"Climate change", "pollution", and "global warming" are the buzzwords we have been hearing over the last few years: there are countless attempts and research projects to reduce the problem of climate-altering emissions in the world.
To date, steel production is one of the sectors with the greatest environmental impact, since the use of carbon-coke (a fundamental component for steel production) generates about 20% of the CO2 in the air. Reducing this percentage could therefore contribute to achieving the "Net Zero Emissions" (NZE) scenario.
To operate according to the principles of the circular economy, steel mills can, for example, transfer certain types of by-products (such as black slag, white slag, and steelmaking dust) to special plants dedicated to their reuse. One way to contribute to reducing harmful emissions can also be through the introduction into the manufacturing process of external waste derivatives—giving new life to all those mixed plastics that cannot be recycled through traditional circuits.
Numerous companies have started far-scale projects in this field; the topic has been around for a long time. A recent case is that of Iren, with the I.Blu plant in Friuli Venezia Giulia (Italy) for the production of the Bluair polymer. This patented material originates from the recycling of post-consumer plastics and represents an opportunity for the steel industry, both from an environmental and performance point of view. The use of Bluair as a reduction agent in redox processes in place of coal allows, according to declarations, a reduction in CO2 emissions of more than 30%, while improving electricity consumption and the overall production quality.
A few months ago, Maire Tecnimont – through its subsidiary NextChem – signed an agreement with Acciaierie d'Italia, Italy's leading steelmaking group, for a feasibility study on the use of syngas (synthetic gas) resulting from waste plastics processing in the former Ilva plant in Taranto. Obtained thanks to NextChem's chemical recycling technology, this particular gas can be used to replace coal dust in the blast furnace or natural gas in direct reduction, both in steel production and refining processes. The use of syngas in such applications could limit the impact of steel production on the environment, thereby reducing the carbon footprint of the entire industry.
In Germany, Hüttenwerke Krupp Mannesmann GmbH (owned by thyssenkrupp, Salzgitter Mannesmann, and Vallourec Tubes) has chosen Paul Wurth S.A., a company of the SMS group, to study the implementation of a syngas generation and injection plant in the blast furnaces of Duisburg. The production of syngas, based in this case on the Ecoloop technology of the homonymous German company, involves the use of about 45,000 tons per year of recycled plastic materials and waste wood chips with high calorific value. Once delivered to HKM, these substances will be processed to reduce the share of fossil reductants.
Perhaps the best-known case is that of the Voestalpine steel mill in Linz, Austria, which operates "the world's largest plant dedicated to injecting plastics into blast furnaces." Since 2007, up to 220,000 tons of end-of-life plastics are used every year as pellets, agglomerates, or granulates as an alternative to more conventional reducing agents.
And to those who may turn up their noses at the idea of burning plastics as an eco-friendly move, the fans of this method reply that steel manufacturing plants reach higher temperatures than most traditional incinerators, with consequent lower CO2 emissions, enabling a reinfusion into the production cycle of a product that would otherwise be thrown away. At present, less than 50% of plastic waste is actually recycled.
Is this the solution? Is it ONE solution? In addition to the use of plastics, several promising technologies are being studied and applied to reduce the environmental impact of one of the most flourishing sectors since the second industrial revolution: CCUS techniques and technologies (underground storage of CO2 resulting from the use of fossil fuels); the use of electrolysis processes to generate the electricity needed by factories; then, there is the big chapter of hydrogen which, when used instead of coal as a reducing agent, generates H2O (water) instead of CO2. Countless projects are being developed in these areas: Aço Verde do Brasil, ArcelorMittal, Tenova, and many others are working on them; the World Steel Association mentions some of them on this page, if you want to know more.
Picture by pasja1000, Pixabay
----
You could be interested in reading:
How green can the wire, cable, tube, and pipe industries be?
