In a groundbreaking development, researchers have unveiled an economically viable method to reduce the environmental impact of both the steel and aluminum industries. By utilizing hydrogen to melt down the toxic red mud, a byproduct of aluminum production, scientists from the Max-Planck-Institut für Eisenforschung in Germany have devised a process that yields green steel in just 10 minutes.

The aluminum industry annually generates approximately 198 million tons (180 million tonnes) of bauxite residue, known as red mud, which poses environmental challenges due to its high alkalinity and rich content of toxic heavy metals. Traditionally, red mud is disposed of in large landfills, incurring high processing costs. Simultaneously, the steel industry contributes significantly to global carbon dioxide emissions, accounting for 8%. Despite these environmental concerns, the demand for steel and aluminum is expected to surge by up to 60% by 2050.

Lead author Matic Jovičević-Klug states, “Our process could simultaneously solve the waste problem of aluminum production and improve the steel industry’s carbon footprint.” Red mud comprises up to 60% iron oxide, and the researchers employed an electric arc furnace and plasma containing 10% hydrogen to melt the mud. This process efficiently reduces it to liquid iron and oxides, enabling easy extraction of pure iron that can be directly processed into steel. The resulting metal oxides solidify into a glass-like material suitable for construction industry applications.

While other studies have produced iron from red mud using coke, leading to contaminated iron and significant carbon dioxide emissions, the current approach using green hydrogen as a reducing agent minimizes these environmental impacts. According to Isnaldi Souza Filho, corresponding author of the study, “If green hydrogen would be used to produce iron from the four billion tonnes of red mud that have been generated in global aluminum production to date, the steel industry could save almost 1.5 billion tonnes of CO2.”

The process not only neutralizes toxic heavy metals present in red mud but also allows for the potential separation and reuse of valuable metals. The researchers emphasize the environmental and economic benefits of producing iron directly from red mud using green hydrogen, with calculations indicating economic feasibility if the mud contains 35% iron oxide.

In addition to its environmental advantages, the plasma reduction process aligns with existing electric arc furnaces widely used in the metal industry, requiring limited investments for industries seeking sustainability. Dierk Raabe, a co-author of the study, emphasizes the importance of considering economic aspects in their research, leaving the decision to utilize this innovative method in the hands of the industry.

By Impact Lab