The steel sector, alongside the energy sector, is one of the largest consumers of fossil coal globally and, consequently, one of the main contributors to industrial carbon dioxide emissions (in the EU, up to 7% of anthropogenic CO2 emissions). Coal is used to produce coke, primarily in blast furnaces. Secondary carriers are used in a still not relevant amount, this impacting negatively on the climate emergency. To mitigate these effects, more sustainable practices have become priorities to maintain the balance of our ecosystem.

To this scope, at the European level, the goal is to limit the temperature increase to 1.5 or 2°C by 2050, compared to pre-industrial levels (as in the Paris Agreement). To achieve it, the EU objective of reducing greenhouse gas emissions was fixed at least 55% by 2030 and becoming completely climate neutral by 2050.

 

Currently, in Europe, 60% of steel production comes from the integrated cycle, starting from ore and using coal as a reducing agent. The remaining share is produced using the electric arc furnace-based (EAF) route where recycled iron scrap is melted. In this case, the main energy input is electricity, although there is a significant fraction of chemical energy (up to 50%.) Chemical energy is provided by fossil sources, natural gas, and coal.

 

Coal is also used as functional to metallurgical operations (e.g., slag foaming, to reduce thermal losses of the furnace, noise and NOx emissions).

The coal used (approximately 12 kg per tonne of steel produced) is one of the main causes of direct carbon dioxide emissions from the electric furnace. Aiming for carbon-neutral steel production, it is therefore essential to reduce or eliminate this source of emissions as much as possible.

The use of substitute materials is a promising solution, especially if they came from waste from other processing cycles, in a circular economy approach. This aspect will become more and more relevant as EAF route will increase in the coming decades. In particular, as a mostly promising approach, strategies have been implemented in European steel plants, aiming to reduce the environmental impact by replacing the integrated cycle with the cycle based on the Direct Reduction of the mineral and the melting process in an electric furnace. That’s’ why such route (DR + EAF) was the approach chosen for the Hydra project.