Historically, iron has been extracted from iron ore with a blast furnace, a process which super-heats ores to separate elements. The blast furnace has remained largely unchanged since early Chinese smelting operations. Most advances in smelting technology involve higher efficiency for the furnace itself.
The extraction process is increasingly automated, with efficient movement of raw ore and separated elements, allowing a high volume of smelted ores. Extracted gasses are now captured and contained for sale or storage, rather than being released into the air. However, the basic extraction method of iron ore remains the same: both the ore and fuel are dropped into the top of the furnace, and air is pumped into the bottom, so the heat level remains high and constant. Elemental metal and slag (waste impurities) flow out of the bottom, while gasses escape from the top. The biggest advance in smelting from early smelting is the Bessemer process, which replaced furnace forging and puddling to remove impurities from iron.