Short answers, pulled from the story.
A blast furnace operates on the principle of chemical reduction where carbon monoxide converts iron oxides to elemental iron. The process relies on a countercurrent exchange between downward-moving ore and upward-flowing hot gases.
Archaeological evidence places cast iron production in China as early as the 5th century BC. Cast iron tools appeared alongside wrought iron artifacts in Shanxi Province by the 9th-8th centuries BC.
The oldest known blast furnaces in Western Europe were built in Durstel Switzerland and Lapphyttan Sweden between 1205 and 1300. Cistercian monks became leading iron producers in Champagne France from the mid-13th century onward.
Abraham Darby began fueling a blast furnace with coke instead of charcoal in 1709 at Coalbrookdale England. This innovation overcame localized wood shortages and reduced labor costs significantly.
The largest blast furnace globally resides in South Korea with volume around 3,000 cubic meters. It produces approximately 6 million tons of iron annually according to recent data.