The Pederson process is a process of refining aluminum that first separates iron by reducing it to metal, and reacting alumina with lime to produce calcium aluminate, which is then leached with sodium hydroxide.[1] It is more environmentally friendly than the more well-known Bayer process.[2] This is because instead of producing alumina slag, also known as red mud, it produces pig iron as a byproduct.[3] Red mud is considered both an economic and environmental challenge in the aluminum industry because it is considered a waste, with little benefit. It destroys the environment with its high pH, and is costly to maintain, even when in a landfill.[4] Iron, however, is used in the manufacture of steel, and has structural uses in civil engineering and chemical uses as a catalyst.[5]
History
editThe Pedersen Process was invented by Harald Pedersen in the 1920s and used in Norway for over 40 years before shutting down due to the Pedersen Process being less economically competitive than the Bayer Process.[6] However, it is believed a modern Pedersen process could be economically viable with "low-quality" bauxite, as even though "low-quality" bauxite has less alumina in the form of trihydrate gibbsite, it has more iron oxide which would be converted to pig iron in the smelting process instead of red mud.[2]
Use in aluminum smelting
editIn most of today's smelting, aluminum ore, also known as bauxite, is first smelted into alumina through the Bayer Process. This step could be replaced by the Pedersen process -- either result in alumina. Unlike the smelting processes of iron and coal into steel or copper and tin into bronze, which require thermal energy, alumina must be smelted with electrical energy. This is done through the Hall–Héroult process, producing 99.5–99.8% pure aluminum.[2][7]
References
edit- ^ Vafeias (2018). "From red to grey: revisiting the Pedersen process to achieve holistic bauxite ore utilisation".
{{cite journal}}: Cite journal requires|journal=(help) - ^ a b c Miller, Jan; Irgens, Aake (2013-04-08). Alumina Production by the Pedersen Process: History and Future. Vol. 1. pp. 975–982. doi:10.1002/9781118647868.ch135. ISBN 9781118636640.
- ^ Konlechner, D., Koenig, R., Preveniou, A., Davris, P., & Balomenos, E. (2021). First industrial scale process concept for the reengineered Pedersen process within ENSUREAL. International Conference on Raw Materials and Circular Economy. https://doi.org/10.3390/materproc2021005008
- ^ Flynn, K., Mendoze, L. R., Hrach, F., Gupta, A., & ST Equipment and Technology. (2019, December). Dry Beneficiation Of Bauxite Minerals Using a Triboelectrostatic Belt Separator. https://steqtech.com/wp-content/uploads/2019/12/SME_2020_Bauxite_Paper_KFlynnetall_Final_Version_STET.pdf
- ^ Iron - element information, properties and uses: Periodic Table. Iron - Element information, properties and uses | Periodic Table. (n.d.). Retrieved April 16, 2022, from https://www.rsc.org/periodic-table/element/26/iron
- ^ Sellaeg, H., Kolbeinsen, L., & Safarian, J. (2017). Iron Separation through Smelting Reduction Process. Norwegian University of Science and Technology. https://www.ntnu.edu/documents/1263635097/1279861738/Iron+Separation+from+Bauxite+through+smelting-reduction+process+HS%2C+JS/8457c706-29ce-4e55-93fa-b600a13be636
- ^ Totten, George E.; MacKenzie, D. Scott (2003). Handbook of Aluminum: Volume 2: Alloy production and materials manufacturing. vol. 2. New York, NY: Marcel Dekker, Inc. ISBN 0-8247-0896-2.