A blast furnace is a steel cylinder lined with refractory. It operates continuously until the lining wears out, which takes many years to occur. The term blast furnace comes from the blast of hot air that is blown into the lower part of the furnace at between 1400º to 2100ºF(Blast Furnace Process, n.d.).
It uses heat to convert iron oxides into liquid iron, which can then be used for a variety of industrial applications. The blast furnace is a brick-lined, stainless-steel stack, which is heated using pre-heated air.
Limestone, coke and iron ore are placed in the blast furnace and heated. The coke, limestone and iron react in the presence of heat, producing slag and liquid iron. These liquids are then drained away and utilized elsewhere.
Molten iron is produced in a blast furnace by the following steps:
- Charge (solid iron ore, coke, and limestone) is constantly dumped into the top of the furnace.
- A blast of hot air is blown into the furnace from the bottom.
- Coke is the fuel that supplies additional heat, increasing the temperature of the charge.
- Chemical reactions occur: coke reacts with oxygen from the air, creating the reducing agent (carbon monoxide), which removes oxygen from the ore.
- Limestone plays the role of flux, forming slag, which floats to the top of the furnace vessel.
- Every hour or so the molten iron is removed and sent on for further processing.
Have you ever experienced iron production from a blast furnace? Share your wonderful experience with us!
