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Blast Furnace Steelmaking
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.
Periodically, the lower part of the furnace (crucible) is emptied and the slag is removed. The drawing shows the holes where the pig iron exits and the slag with the impurities are marked.
Esquema del horno alto
The pig iron is transported in closed ladles to keep it in a liquid state to the refining facilities where secondary metallurgy is carried out. This process will determine both the chemical composition of the steel and its metallurgical quality in terms of cleanliness of impurities and low content of gases such as oxygen and nitrogen.
The most widely used type of installation is the LD converter, which is a cylindrical container with a conical upper part in which liquid iron is deposited, to which oxygen is injected to maintain its temperature and facilitate the cleaning of impurities. Another widely used process is called AOD, but there are more denominations with variants applied to the original LD.
At this point in the process, we can speak of having steel, although it is still in a liquid state.
In later posts, we will see the solidification and transformation processes until we reach the commercial steel products as we know them in industrial practice when we manufacture parts with high or low mechanical requirements.
