ISLAG aims at improving the valorization of the slag coming from the electric steelmaking process route, supporting good practices in steelworks and exploring new recycling paths by facilitating implementation of a real “industrial symbiosis”

Slags are the main by-products produced in steelworks, representing about 90% by mass of all by-products. Noticeable efforts are spent nowadays to improve the re-use and recycling of these by-products both inside and outside the steelmaking cycle, in compliance with the concept of “Circular Economy,” which is an absolute priority for the whole EU industry nowadays and is also strongly emphasized in the Strategic Research Agenda of the European Steel Technology Platform (ESTEP) and of the Clean Steel Partnership (CSP).

However, the actual possibility to recycle the slag in the most economical and environmentally friendly way strongly depends on the provision of knowledge on its chemical composition. Moreover, usually steelworks are keen to monitor and control the steel quality in the liquid stage, being steel their product, while less attention is put on the characterization of liquid slag, even though this secondary product might convey relevant savings, if suitably reused or recycled inside or outside the steel cycle, and/or relevant costs, if disposed. This is partly due to the lack of suitable and cost-effective systems for on-line slag characterization at the liquid stage, where suitable correction actions can still be put in place to optimize the slagging process and adjusting the slag features for their optimal reuse and valorisation without compromising the metallurgical function of the slag with respect to liquid steel quality.
Also for solid slag, practical tools for fast and specific characterization are missing, although they would be highly beneficial for improving slag reuse and valorisation. In effects, currently slags are stored into specific areas and analysed to assess whether part of them can be internally reused or sold for external applications. However, the mixing of slags coming from the production of different steel qualities with different treatments hampers the possibility to assign to each single slag slot the most suitable and cost-efficient destination.

The problem for steelworks is even more sensitive when dealing with steel grades which are new or seldomly produced: obviously the focus of their preliminary investigation is on achieving the target features for the steel, by neglecting slag features and by a-posteriori adjusting their operating practices or management procedures, as tools or systems which could provide support on this aspect are missing.