A blast furnace is a type of furnace for smelting whereby the combustion material and ore are supplied with air from the bottom of the chamber such that the chemical reaction does not take place only at the surface. Typically this is used for the production of pig iron from iron ore.
Modern blast furnaces 
"Deadman's foot" (Salamander) at Henrichshütte Hattingen, Germany
Blast furnace with elevator at Henrichshütte Hattingen, Germany
"Achhalle" (casting hall) at blast furnace no. 5, Landschaftspark Duisburg-Nord, Germany