Slag as heat storage material for waste heat recovery (leaded by CIC Energigune).

The primary energy requirements of heavy industries are intensive. Even if companies are putting a big effort to reduce the needed input energy and optimize the overall energetic efficiency, between 30-50% of this energy is lost during the manufacturing process.

Within the scope of RESLAG project, the waste energy recovery of the steelmaking industry is addressed. In this frame, the particular issue of the Electric Arc Furnace (EAF) technology is selected due to its increasing implementation on worldwide steel mills. This productive methodology requires a high electric energy input, which afterwards around 50% is lost as waste heat, combustion products and others.

RESLAG project aims to design and construct a high temperature and high thermal performance heat recovery system oriented to the EAF off-gas with a double objective:

  • Recover up to a 15% of the primary energy, contained in the EAF off-gas stream. RESLAG project will target a highly efficient steel manufacturing process.
  • Use of steel slag as a successful solution to store the recovered heat from the EAF. This technology adapted for the steel production will approach this industry to a close to zero waste product generation (slag), as the valorization of the slag as heat storage material will be demonstrated.

Schematic view of pilot. Waste heat recovery solution proposed in RESLAG project for the Electric Arc Furnace (EAF) steelmaking process. The targeted recovery is up to a 15% of the primary energy input.

The potential of the proposed system is based on its flexibility to be adapted also to different environments or also to other energy-intensive industrial sectors such as cement, glass, pulp and paper or chemical industries. Even if it is not addressed on RESLAG project, the combination of the proposed storage with a second TES unit could be a satisfactory solution to obtain a continuous heat source at constant temperature, opening new possibilities for its exploitation.


Development of pilot 2. Connections with the RESLAG project different stages.

A fast and effective technologic transfer of the developed heat storage system technology will be guaranteed, as one of the world leaders in the steel production, Arcelor Mittal, will be in full collaboration with the research activities associated to the concept demonstration pilot. Moreover, the implementation of the design concept will be done in one of the steelmaking plants of Arcelor Mittal in Spain.

ArcelorMittal Sestao
ArcelorMittal Sestao

Arcelor MIttal, one of the world leaders in the steelmaking industry will implement the developed concept demonstrator in one of its plants in Spain. This will ensure a fast and effective technology transfer to the real market.