Slags from DRI-EAF steel making – a case study on upcoming by-products from the decarbonized steel industry

Due to the Green Deal proposed by the European Union, several industry sectors in Europe are forced to change the production techniques towards a zero-carbon dioxide emission until 2050. For the steel industry the substitution of fossil fuel, used in the blast furnace (BF), by hydrogen as reduction agent relates to the introduction of new technologies and aggregates. Nowadays, only a small amount of shaft furnaces using natural gas for reduction of iron ores to produce direct reduced iron (DRI). However, this combination is one of the favoured future hydrogen operated routes of alternative steel making in the European Union. The crude steel is, thereby, produced from solid DRI together with scrap molten within the electric arc furnace (EAF). Thus, the minor and trace element composition of the produced EAF slags is directly inherited from the input materials because no density driven phases separation takes place in the DRI which is one major difference to the traditional BF route.

Here we present the results of mineralogical, chemical as well as construction technological investigations carried out on one exemplary slag from the EAF route were app. 2/3 of the input material was sponge iron. The main emphasis of the presented study lies on the ongoing applicability of the EAF slags produced in the future as secondary product in the context of steel industry feature the planned reduction of carbon dioxide emissions.