Legal and environmental bottlenecks and opportunities for slag-based products valorisation
Blast furnace slags and steel slags are industrial residues co-generated by steel production. With 48 million tonnes each year in the EU, steel slags represent a considerable potential of by-products or secondary materials for use mainly in the construction industry. According to their chemical and physical properties, these slags can be well-performing substitutes for backfilling materials, natural aggregates for concrete and mortars, constituents for cement, activating additives for hydraulic binders and agricultural fertilisers. Through adequate regulatory and contractual frameworks, slag valorisation can provide emblematic examples of industrial symbiosis, with great economic and environmental benefits such as natural resources and energy savings and reduction of greenhouse gases. As it concerns several key environmental national and European regulations mostly regarding waste, this ambitious potential should overcome discrepancies in the approaches for by-products, secondary materials and their performance and risk assessments. Slag-based product valorisation should be mobilised at its maximum in order to reap benefits in terms of low-carbon technologies and products and optimisation of the construction materials industry in the context of the European strategic long-term vision for a prosperous, modern, competitive and climate neutral economy. This is all the more important as there is already a demand in the European market for slag-based products. Implementation of the European Union’s circular economy policy gives a strong impetus to full mobilisation of the opportunities for slag-based product valorisation.