Blast Furnace A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals and its alloys, generally iron, but also others such as lead or copper. In a blast furnace fuel (coke), ores, and flux (limestone) are continuously supplied through the top of the furnace, while a hot blast of air (sometimes with oxygen enrichment) is blown into the lower section of the furnace through a series of pipes called tuyeres, so that the chemical reactions take place througho