|This article is part of the Global Steel Plant Tracker, a project of Global Energy Monitor.|
A blast furnace (BF) is a type of metallurgical furnace used to produce industrial metals, generally, pig iron (aka hot metal), an intermediate product in conventional, coal-based steelmaking.
A blast furnace (BF) is used to smelt iron from iron ore. Blast furnaces produce pig iron (aka hot metal) by reducing carbon (coke from coking coal) in the presence of a fluxing agent like limestone. The BF steelmaking process often includes pelletization and sintering of iron ore, and coking of coal as preliminary processes for iron and steelmaking. An ironmaking BF consists of: a hearth at the bottom of the furnace, a bosh, an immediate zone between the hearth and the stack (the shaft of the furnace) and the hottest part of the furnace, and the stack, or the shaft, which extends to the top of the furnace.
The stack consists of alternating layers of coke, iron ore and fluxes/additives. These materials are then burned rapidly with forced air (up to 1000°C) from the tuyeres at the base of the furnace. This results in the creation of pig iron, which is then transferred to the basic oxygen furnace for the creation of steel. The BF-BOF steelmaking process often includes pelletizing and sintering of iron ore, and coking of metallurgical coal as preliminary processes for iron and steelmaking. Producing one tonne of steel through the BF-BOF steelmaking route emits around 2.2 tonnes of CO2 / tonne crude steel and requires roughly 20.8 GJ / tonne crude steel of energy, assuming global average electricity carbon intensity.
Options for decarbonizing the BF-BOF steelmaking route are difficult and limited because of the use of metallurgical coal as a reductant in the ironmaking process: as coal is heated to melt the iron ore, carbon monoxide is produced that reduces oxygen in the iron ore but releases CO2 as a byproduct, called process emissions. Given that process emissions are a fundamental step of BF-BOF steelmaking, the abatement potential is limited, with the use of zero carbon electricity in the BF-BOF steelmaking process reducing emissions by just 7.4%. Hydrogen can be used to partially substitute metallurgical coal as a reductant in the BF-BOF steelmaking process, with a maximum carbon emissions reduction of 21.4% per tonne of steel. Together, zero carbon electricity and hydrogen injection can abate a maximum of 28.8% of CO2 emissions in BF-BOF steelmaking, based on current estimates.
- Iron ore
- Pig iron (aka hot metal)
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- The Production of Pig Iron
- Blast Furnace - an overview
- Steel Industry Co-Products
- Pig iron - blast furnace route