Open hearth furnace
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The Open hearth furnace (OHF) is a type of furnace that can be used to produce steel using the Siemens-Martin process. It uses pig iron and scrap to produce steel. The open hearth furnace replaced the previous “Bessemer process” for steel production.[1] Today, the open hearth furnace process accounts for less than 1% of the global steelmaking capacity and is mainly found in emerging economies where there is a need for lower capital costs.[2]
The open hearth furnace uses raw materials like scrap, pig iron and limestone as input. Fuels such as oil or natural gas are used to heat the furnace. The output of the OHF is molten steel.[3]
The Process
In the first step, the furnace is heated. Steel scrap (i.e., steel that is being recycled from other sources, such as buildings and construction) is melted in the furnace, together with pig iron (hot metal) from another primary production process (for example the Blast Furnace). After the mixture is melted, limestone (a slag-forming agent that helps to remove impurities) is added. Oxygen and the molten pig iron react, oxidizing the excess carbon, and creating carbon monoxide. This process of decreasing carbon content is known as “decarburization”. Other reactions and impurities in the mixture can contribute to the decarburization process, and iron oxide ore be added to increase it. Once the desired carbon content is reached, the raw (molten) steel is separated from the waste matter (known as slag). At this point, it can be further customized through the addition of different alloys, or be cast into the desired shape, like ingots or slabs. [2][3]
Decarbonization strategies
The OHF process is highly energy-intensive and is considered to have an inefficient energy input versus steel output ratio. Nowadays, it is therefore largely replaced by the Basic Oxygen Furnace and Electric Arc Furnace (EAF).[2] Where it does exist, emissions can be slightly reduced through increased scrap use (reducing the need for new iron ore), improved fuel efficiency (through better burners and heat recovery systems), and combined use with EAFs. Carbon capture, utilization, and storage could be an additional technology for emission reductions in the future, if developed successfully.
References
- ↑ Philippe Mioche, « Et l'acier créa l'Europe », Matériaux pour l'histoire de notre temps, vol. 47, 1997, p. 29-36
- ↑ 2.0 2.1 2.2 Swalec & Shearer, 2021, Pedal to the Metal, Global Energy Monitor.
- ↑ 3.0 3.1 Wente, E., Nutting, J., & Wondris, E. F. (n.d.). steel—Primary steelmaking | Britannica [Encyclopedia Britannica]. Steel. https://www.britannica.com/technology/steel
External links
- Open hearth furnace - Britannica
- Open Hearth - an overview | ScienceDirect Topics
- Open Hearth Furnace | Wikipedia
- Open_Hearth_Furnace | (chemeurope.com)
This page uses material from the Wikipedia page Open hearth furnace under the provisions of the Creative Commons Attribution-ShareAlike 3.0 Unported License.
Abeckford21 (talk) 22:26, 12 July 2021 (UTC)
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