Hydrometallurgy and phytomanagement approaches for steel slag management (HYPASS)

International audienceSteel slags are major by-products produced by the steel and iron industry. While they are considered as industrial waste, slags represent an important potential economic resource because they often contain significant amounts of valuable "Strategic Metals" (SMs). These metals are essentially used as alloying elements in the steel industry as well as in catalysts and pigments in the chemical industry and as raw material in green technologies (photovoltaic cells, wind turbines and electric motors). During the last decade the global steel production driven by China has doubled and the development of renewable energies (wind and solar) and electrics cars has dramatically increased. This has sharply affected global SMs demand, and there is no doubt today that production and consumption of SMs will must face a major economic pressure in upcoming years. In this context, the importance of hydrometallurgy in production and recycling of SMs cannot be stressed enough. However, improving or even optimizing these processes is clearly required. In addition, although steel slags are classified as non-hazardous thermal waste according to the decree 2002-540 and the United States Environmental Protection Agency, it is well known that most metals they contain are quite toxic to living organisms and may pose serious environmental issues. In France, the "Centre Technique de Promotion des Laitiers sidérurgiques" (CTPL) estimated that the total available stock of slags (including all slag families) was about 17 480 600 tons at the end of 2015. Thus, reusing steel slags appears the option of choice to ensure their sustainable management as well as to decrease their environmental concerns