Steel recycling and anti-alloying

Researchers: Ashwini Nalge and Ida Kero

The doctoral studies in this project will explore how anti-alloying may be applied to abate the negative effects of unwanted (tramp) elements in recycled steel.

Steel is one of the most recycled commodities in the world. However, most of what is called recycling today, is actually downcycling – i.e., that the recycled products exhibit significantly poorer quality than the original products. As an example, it is not possible to make new cars out of old, scrapped cars because of quality constraints. The main goal of this project is to identify and develop methods to improve steel recycling and minimize our reliance on mining of iron ore.

This project concerns multiple loop steel recycling and how negative impacts of impurities from various types of scrap metal can be counteracted by smart alloy design. Today, the principal strategy to limit the negative effects of contamination is by dilution with iron from primary sources. Even if scrap sorting and information sharing may be improved in the future, steel recycling will need to cope with lower levels of purity and larger variation in the chemical composition for a long time. The concept of anti-alloying means identifying additives and developing methods to neutralize the contaminants without removing them.

Sustainability aspects

The current production of iron and steel is based on the blast furnace process and has many negative effects on the environment. As an example, the steel industry accounts for around 8% of global CO₂ emissions. It is recognized as one of the most difficult industries to decarbonize (hard-to abate sector). Increasing the use of recycled scrap is compatible with a circular economy and would not only reduce the emissions of greenhouse gases but also the need for mining. Iron ore mining can, for example, be negative with respect to land use and biodiversity. It can also be competing with indigenous peoples’ rights.

This project supports a circular economy and promotes recycling of end-of-life steel materials in optimized processes which avoids downcycling and retains the value of the most advanced steel types even after several recycling loops. This way, it helps to lessen the supply chain risks and the dependency of mined minerals. This, in turn, reduces the industrial greenhouse gas emissions, water and energy consumption and land area use. As such, this project directly supports the UN SDG’s 8, 9, 11, 12, and 15.