Starting with iron as raw material, either in the form of ore or as a concentrate in the form of synthesized iron, pellets, etc., it is melted in a blast furnace (as can be seen in image 2), with coal and coke, assisted by fluxes. In this melting process, a mass of liquid steel is formed, covered by a fluid slag in which a large part of the impurities remains. The aim is to obtain liquid pig iron.