Scientists at the Max-Planck Institute for Iron Research have developed an innovative method to transform waste from aluminum production, known as “red mud” or Rotschlamm, into green steel, thus avoiding a significant environmental impact.
This approach involves the use of an electric arc furnace , a conventional technology in the steel industry, to convert the iron oxide present in the Rotschlamm into iron through the use of hydrogen plasma. With approximately four billion tonnes of red mud accumulated globally, it is estimated that this method could generate around 700 million tonnes of CO 2 -free steel, equivalent to a third of annual global steel production.
Red mud in aluminum mining
Conventional steel and aluminum production has a significant environmental impact, with the steel industry responsible for 8% of global CO 2 emissions . In contrast, the innovative proposed method would not only address the problem of waste from aluminum production, but also improve the carbon footprint of the steel industry. If green hydrogen is used to transform the four billion tons of Rotschlamm, the steel industry could reduce approximately 1.5 billion tons of CO 2 .
The procedure involves melting the Rotschlamm and reducing the iron oxide to iron in just ten minutes using a plasma containing 10% hydrogen. The resulting iron is of such purity that it can be directly used in the production of steel. The remaining metal oxides, which are neither corrosive nor dangerous, solidify into a glass-like material, which can find useful applications in construction.
This approach also decreases the toxicity of heavy metals present in Rotschlamm. Valuable metals could be separated and recycled, while those remaining in the metal oxides remain safe and non-leachable. From an economic perspective, the process is cost-effective even using green hydrogen and partially renewable electricity, especially when considering the costs associated with removing red mud.
Since electric arc furnaces are common in the metallurgical industry, the adoption of this technique for more sustainable production would be facilitated. The industry now has the opportunity to implement this innovative Rotschlamm plasma reduction to iron, marking a significant shift towards sustainability.
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