Blast furnace
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The Blast Furnace (BF) is a furnace used in the iron-making process. It uses iron ore and limestone as input, metallurgical coal (converted to coke) as a reducing agent, and creates pig iron (also known as crude iron or hot metal) as output. This pig iron can then be used in other furnaces, like the Basic Oxygen Furnace (BOF) or Electric Arc Furnace (EAF), to produce steel.
Iron Production
Using the Blast Furnace requires some raw material preparation. The iron ore needs to be converted into pellets by going through a pelletizer and a sinter machine, which uses high temperatures to convert the material into a product optimal for the Blast Furnace.[1] During this activity, the pellets are processed at very high temperatures. The energy intensity needed depends on the quality of the iron ore, among other factors.[2] In order for the coal to be usable, it first needs to be converted into coke. This is done under the pressure of high temperatures in “coke ovens”. Lastly, limestone is crushed to serve as a fluxing agent during the iron-ore conversion process.
The iron is produced through the removal of oxygen and impurities from the iron ore.[3] To do so, iron ore pellets, coke, and limestone are added to the Blast Furnace. The coke is heated to melt the iron ore, releasing carbon monoxide. This process reduces the oxygen in the iron ore, causing the emission of CO2 as a byproduct of the resulting pig iron.[4][5]
Carbon Emissions
Emissions in the raw material preparation stem not only from the burning of coal, but also from the various operating processes and electricity consumption.[5] Additionally, sourcing materials causes indirect emissions, such as the methane emissions released during coal mining, increasing the reported carbon footprint of the Blast Furnace process.[6][7] Because the Blast Furnace uses coal as a reducing agent, the production route has a very low abatement potential, which refers to the possibility to reduce emissions.[8][9][4]
Decarbonisation Strategies
Some of the potential decarbonisation strategies available for blast furnaces include:
- Partial substitution of the reducing agent coal with hydrogen or biomass
- Switching to zero-carbon electricity, which on its own could eliminate about 7.4% of the emissions.[4]
- Carbon capture, utilisation and storage
It is predicted that even with substitution of coal and switch to zero-carbon electricity adopted together, more than 70% of the carbon emissions would remain in the iron production using a blast furnace.[4]
New research also suggests an opportunity to use perovskite to substitute coke as a reducing agent and create carbon-loops, thus offering a potential solution to reducing up to 70% of BF-BOF emissions. However, at the current stage this research is not advanced enough to be implemented soon.[10] The best option for reducing emissions, however, is to change the production process for ironmaking, by switching to DRI, smelting-reduced iron, and through the deployment of other emissions-reduction technologies.
If the world continues to use Blast Furnaces until the end of their lifetime, it needs to find ways to reduce emissions in the meantime. The gasses released as a byproduct of the production (such as gasses from the coke oven and blast furnace) could be used as energy input in other processes. This can reduce energy needs at the steel plants and lower energy-related emissions.[2] Gasses can also be used to process chemicals. If these chemicals are then recycled within circular products, emissions can be lowered further.[11] Nevertheless, it will need a maximized use of low-carbon or circular inputs to abate as many emissions as possible.
References
- ↑ ArcelorMittal (2022). "Raw materials - Sinter plant". ArcelorMittal.
- ↑ 2.0 2.1 IEA (2020). "Iron and Steel Technology Roadmap—Towards more sustainable steelmaking". International Energy Agency.
- ↑ World Steel Association (2021). "Climate change and the production of iron and steel" (PDF). World Steel Association.
- ↑ 4.0 4.1 4.2 4.3 Swalec, C. and Shearer, C. (2021). "Pedal To The Metal: No Time To Delay Decarbonizing The Global Steel Sector". Global Energy Monitor.
- ↑ 5.0 5.1 Sadoway (2019). "Donald Sadoway at EmTech MENA 2019: Steel Production without Co2 Emissions". YouTube.
- ↑ Swalec, C. and Grigsby-Schulte, A. (2023). "Pedal To The Metal: It's Time To Shift Steel Decarbonization Into High Gear". Global Energy Monitor.
- ↑ U.S. EPA (2015). "Sources of Coal Mine Methane [Overviews and Factsheets]". U.S. Environmental Protection Agency.
- ↑ Gray & M’barek, 2022: https://www.transitionzero.org/blog/stranded-assets-carbon-pricing-risk-steel
- ↑ How to Avoid a Climate Disaster - The Solutions We Have and the Breakthroughs We Need (Gates, 2021)
- ↑ Kildahl et al., 2023: https://www.sciencedirect.com/science/article/pii/S095965262300121X?via%3Dihub
- ↑ Energy Transitions Commission, 2021: https://www.energy-transitions.org/publications/steeling-demand/
External links
- The Production of Pig Iron
- Blast Furnace - an overview
- Steel Industry Co-Products
- Pig iron - blast furnace route
Abeckford21 (talk) 07:01, 29 June 2021 (UTC)
