Method for producing iron from toxic red mud in 10 minutes

The German research team's new method will help produce high-purity iron from red mud, a waste product of the aluminum industry, in just 10 minutes.

A group of scientists from the Max-Planck-Institut für Eisenforschung, an iron research center in Germany, developed a method to turn toxic red mud by-products from aluminum production into iron, which then turns into steel. green", New Atlas reported on February 6. New research published in the journal Nature.

Researchers find a way to turn waste red mud from aluminum production into iron. (Photo: Depositphotos).

The aluminum industry generates about 180 million tons of bauxite residue, or red mud , each year. This substance is very corrosive because it is highly alkaline and rich in toxic heavy metals. In countries such as Australia, China, and Brazil, excess red mud is often disposed of in giant landfills with high treatment costs. The steel industry is equally harmful to the environment, contributing 8% of global CO ₂ emissions . However, demand for steel and aluminum is expected to increase by up to 60% by 2050.

"Our process can simultaneously solve the waste problem in aluminum production and reduce the carbon emissions of the steel industry ," said Matic Jovicevic-Klug, lead author of the new study.

Red mud has 60% iron oxide . Melting red mud in an electric arc furnace with a plasma containing 10% hydrogen reduces the substance to liquid iron and liquid oxide, from which the iron can be easily extracted. The plasma reduction technique takes about 10 minutes and produces very pure iron, which can be processed directly into steel. Metal oxides that are no longer corrosive will harden as they cool. Therefore, they can be turned into glass-like materials and used as backfill materials in the construction industry.

"If green hydrogen was used to produce iron from the 4 billion tons of red mud generated in global aluminum production to date, the steel industry could reduce nearly 1.5 billion tons of CO ₂ " , Isnaldi Souza Filho, research team member, said.

The toxic heavy metals present in the original red mud are "virtually neutralized" by the new process. Any remaining heavy metals are tightly bound in metal oxides and cannot be washed away with water as with red mud in landfills.

"After the reduction process, we detected chromium in the iron. Other heavy and precious metals may also have gone into the iron or into a separate place. We will explore this in further studies. The precious metals can then be separated and reused ," Jovicevic-Klug said. The research team also said that producing iron from red mud directly with green hydrogen brings great benefits to the environment and also brings economic benefits.