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==History==
==History==
A common practice since the early 1900s and extensively capitalized during [[World War II]], aluminium recycling is not new. It was, however, a low-profile activity until the late 1960s, when the exploding popularity of aluminium [[beverage can]]s finally placed recycling into the public consciousness.<ref>{{cite book|last=Schlesinger|first=Mark|title=Aluminum Recycling|year=2006|url=https://books.google.com/books?id=DtX1nbel49kC|publisher=CRC Press|isbn=978-0-8493-9662-5|page=248}}</ref>

[[File:Salvage demo.jpg|thumb|upright|Model promoting aluminium recycling at [[Douglas Aircraft Company]] in 1942]]
[[File:Salvage demo.jpg|thumb|upright|Model promoting aluminium recycling at [[Douglas Aircraft Company]] in 1942]]
Although aluminium in its pure form has been produced as early as 1825<ref>{{Cite journal |last=Kvande |first=Halvor |date=2008-08-01 |title=Two hundred years of aluminum ... or is it aluminium? |url=https://doi.org/10.1007/s11837-008-0102-3 |journal=JOM |language=en |volume=60 |issue=8 |pages=23–24 |doi=10.1007/s11837-008-0102-3 |issn=1543-1851}}</ref>, secondary aluminium production, or recycling, rose in volume with the introduction of industrially viable primary aluminium processes, namely the combination of the Bayer and Hall-Héroult processes. The Hall-Héroult process for aluminium production from alumina was invented in 1886 by Charles Hall and Paul Héroult<ref>{{Cite journal |last=Reverdy |first=Michel |last2=Potocnik |first2=Vinko |date=2020 |title=History of Inventions and Innovations for Aluminum Production |url=https://link.springer.com/chapter/10.1007/978-3-030-36296-6_175 |journal=TMS 2020 149th Annual Meeting & Exhibition Supplemental Proceedings |series=The Minerals, Metals & Materials Series |language=en |location=Cham |publisher=Springer International Publishing |pages=1895–1910 |doi=10.1007/978-3-030-36296-6_175 |isbn=978-3-030-36296-6}}</ref>. Carl Josef Bayer created a multi-step process to convert raw Bauxite into alumina in 1888<ref>{{Cite journal |last=Habashi |first=Fathi |title=Bayer's process process for Alumina Production: A Historical
Sources for recycled aluminium include [[aircraft]], [[automobile]]s, [[bicycle]]s, [[boat]]s, [[computer]]s, [[cookware]], [[Rain gutter|gutters]], [[siding (construction)|siding]], [[wire]], and many other products that need a strong lightweight material, or a material with high [[thermal conductivity]]. As recycling does not transmute the element, aluminium can be recycled indefinitely and still be used to produce any product for which new aluminium could have been used.<ref>{{Cite web |url=http://www.wasteonline.org.uk/resources/InformationSheets/metals.htm |title=WasteOnline: Metals aluminium and steel recycling |access-date=2006-06-06 |archive-url=https://web.archive.org/web/20071016051136/http://www.wasteonline.org.uk/resources/InformationSheets/metals.htm |archive-date=2007-10-16 |url-status=dead }}</ref>
Perspective |url=http://acshist.scs.illinois.edu/bulletin_open_access/num17-18/num17-18%20p15-19.pdf |journal=Bull. Hist. Chem |issue=}}</ref>. As aluminium production rose with the use of these two processes, aluminium recycling grew too. In 1904, the first two aluminium can recycling plants were built in the United States; one recycling plant was built in Chicago, Illinois and the other was built in Cleveland, Ohio<ref>{{Cite book |last=Byers |first=Ann |url=https://books.google.com/books?id=OCpmDwAAQBAJ&newbks=0&hl=en |title=Reuse It: The History of Modern Recycling |date=2017-12-15 |publisher=Cavendish Square Publishing, LLC |isbn=978-1-5026-3127-5 |language=en}}</ref>. Aluminium recycling increased most significantly in volume when metal resources were strained during WWI, as the U.S. government campaigned for civilians to donate old products such as aluminium pots, pans, boats, vehicles, and toys to recycle for the construction of aluminium airframes<ref>{{Cite book |last=Byers |first=Ann |url=https://books.google.com/books?id=OCpmDwAAQBAJ&newbks=0&hl=en |title=Reuse It: The History of Modern Recycling |date=2017-12-15 |publisher=Cavendish Square Publishing, LLC |isbn=978-1-5026-3127-5 |language=en}}</ref>.

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Revision as of 23:00, 6 November 2023

An aluminium recycling symbol.
The European Committee for Standardization logo for aluminium recycling.

Aluminium recycling is the process by which scrap aluminium can be reused in products after its initial production.[1] The process involves simply re-melting the metal, which is far less expensive and energy-intensive than creating new aluminium (Recycled Aluminum-Secondary Aluminium)[2] through the electrolysis of aluminium oxide (Al2O3),[3] which must first be mined from bauxite ore and then refined into aluminium oxide using the Bayer process and then refined again into aluminium metal using the Hall–Héroult process.[4]

Recycling scrap aluminium requires only 5% of the energy used to make new aluminium from the raw ore.[5] For this reason, approximately 36% of all aluminium produced in the United States comes from old recycled scrap.[6] Used beverage containers are the largest component of processed aluminum scrap, and most of it is manufactured back into aluminium cans.[7]

History

Model promoting aluminium recycling at Douglas Aircraft Company in 1942

Although aluminium in its pure form has been produced as early as 1825[8], secondary aluminium production, or recycling, rose in volume with the introduction of industrially viable primary aluminium processes, namely the combination of the Bayer and Hall-Héroult processes. The Hall-Héroult process for aluminium production from alumina was invented in 1886 by Charles Hall and Paul Héroult[9]. Carl Josef Bayer created a multi-step process to convert raw Bauxite into alumina in 1888[10]. As aluminium production rose with the use of these two processes, aluminium recycling grew too. In 1904, the first two aluminium can recycling plants were built in the United States; one recycling plant was built in Chicago, Illinois and the other was built in Cleveland, Ohio[11]. Aluminium recycling increased most significantly in volume when metal resources were strained during WWI, as the U.S. government campaigned for civilians to donate old products such as aluminium pots, pans, boats, vehicles, and toys to recycle for the construction of aluminium airframes[12].

Hydraulic press and baled cans prepared for transport

Advantages

Aluminium is an infinitely recyclable material, and it takes up to 95 percent less energy to recycle it than to produce primary aluminum, which also limits emissions, including greenhouse gases. Today, about 75 percent of all aluminum produced in history, nearly a billion tons, is still in use.[13]

The recycling of aluminium generally produces significant cost savings over the production of new aluminium, even when the cost of collection, separation and recycling are taken into account.[14] Over the long term, even larger national savings are made when the reduction in the capital costs associated with landfills, mines, and international shipping of raw aluminium are considered.

Energy savings

Recycling aluminium uses about 5% of the energy required to create aluminium from bauxite;[15][better source needed] the amount of energy required to convert aluminium oxide into aluminium can be vividly seen when the process is reversed during the combustion of thermite or ammonium perchlorate composite propellant.

Aluminium die extrusion is a specific way of getting reusable material from aluminium scraps but does not require a large energy output of a melting process. In 2003, half of the products manufactured with aluminium were sourced from recycled aluminium material.[16]

Environmental savings

The benefit with respect to emissions of carbon dioxide depends in part on the type of energy used. Electrolysis can be done using electricity from non-fossil-fuel sources, such as nuclear, geothermal, hydroelectric, or solar. Aluminium production is attracted to sources of cheap electricity. Canada, Brazil, Norway, and Venezuela have 61 to 99% hydroelectric power and are major aluminium producers. However the anodes widely used in the Hall–Héroult process are made of carbon and are consumed during aluminum production, generating large quantities of carbon dioxide, regardless of electricity source.[17] Efforts are underway to eliminate the need for carbon anodes.[18] The use of recycled aluminium also decreases the need for mining and refining bauxite.

The vast amount of aluminium used means that even small percentage losses are large expenses, so the flow of material is well monitored and accounted for financial reasons. Efficient production and recycling benefits the environment as well.[19]

Impact

Environmental

Because many countries continue to rely on coal-generated electricity for aluminium production, the aluminium industry contributes to 2% of global greenhouse gas emissions, around 1.1 billion tons of carbon dioxide[20]. Many countries now seek to decarbonize aluminium not only as it is the second most used metal in the world, but also because it would heavily address the total greenhouse gas emissions in an effort to slow climate change[21].

As one of the most recyclable –and recycled– materials in use today, aluminium can be virtually infinitely recycled. Since recycled aluminium takes 5% of the energy used to make new aluminium, around 75% of aluminium manufactured continues to be in use today. According to the Aluminium Association, in industrial markets such as automotive and building, aluminium is recycled at rates of up to 90%.

Since 1991, greenhouse gas emissions from aluminium cans have dropped about 40%, similar to energy demand levels. This can be attributed to a reduction in the carbon intensity of primary aluminium production, improving the efficacy of manufacturing operations, and lighter cans[22]. While primary aluminium only accounts for 26.6% of the can, it makes up the major source of the can’s carbon footprint. For example, as of 2020, 86% of China’s aluminium production relies mostly on coal-generated electricity. On the other hand, Canada sources roughly 90% of its primary aluminium production using hydroelectric power, considering it to be the most sustainable in the world[23].

Aluminium and its applications are wide and numerous–from defense construction and electrical transmission to playing a key role in emission-reducing goods (electric vehicles and solar panels). As such, countries have begun to decarbonize aluminium to combat global climate change.

Economic

Aluminium recycling has several economic benefits when done properly. In fact, the Environmental Protection Agency considers recycling a “critical” part of the United States economy, contributing to tax revenue, wages, and job creation[24]. By facilitating scrap handling and improving its efficiency –from “end of life” scrap to repurposing scrap throughout the production stage (“in-house” scrap) –aluminium recycling helps in achieving the goals of a circular economy[25]. This type of economy focuses on minimizing the extraction of natural resources, leading to a reduction of consumer and industrial waste. A few examples of countries that have adopted the shift to a circular economy include the European Union, Finland, France, Slovenia, Italy, Germany, and the Netherlands[26].

A recent study conducted within the United States has highlighted some ways that aluminium recycling has proven to have economic benefits, including:

  • Job creation: Contributing to more than 100,000 jobs in the reprocessing to the United States economy.
  • Economic activity: Bring about $1.6 billion in material sales
  • Wage Increases: Increasing the wages of waste management and the recycling industry from $2.1 billion to $5 billion.
  • Energy Conservation: Save enough energy to power 1.5 million homes per year.
  • Waste Management: Maintain more than 1 million tons of waste out of landfills every year.

As countries take note of the various economic and environmental benefits of aluminium recycling, increased efforts are expected to improve the efficacy of this process.

Process for beverage cans

Aluminium beverage cans are usually recycled by the following method:[27]

  1. Cans are first divided from municipal waste, usually through an eddy current separator, and cut into small, equally sized pieces to lessen the volume and make it easier for the machines that separate them.
  2. Pieces are cleaned chemically/mechanically and blocked to minimize oxidation losses when melted. (The surface of aluminium readily oxidizes back into aluminium oxide when exposed to oxygen.[28])
  3. Blocks are loaded into the furnace and heated to 750 °C ± 100 °C to produce molten aluminium.
  4. Dross is removed, and the dissolved hydrogen is degassed. (Molten aluminium readily disassociates hydrogen from water vapor and hydrocarbon contaminants.) This is typically done with chlorine and nitrogen gas. Hexachloroethane tablets are normally used as the source for chlorine. Ammonium perchlorate can also be used, as it decomposes mainly into chlorine, nitrogen, and oxygen when heated.[29]
  5. Samples are taken for spectroscopic analysis. Depending on the final product desired, high-purity aluminium, copper, zinc, manganese, silicon, and/or magnesium is added to alter the molten composition to the proper alloy specification. The top-five aluminium alloys produced are 6061, 7075, 1100, 6063, and 2024.
  6. The furnace is tapped, the molten aluminium poured out, and the process is repeated again for the next batch. Depending on the end product, it may be cast into ingots, billets, or rods, formed into large slabs for rolling, atomized into powder, sent to an extruder, or transported in its molten state to manufacturing facilities for further processing.[30]

Ingot production using reverberatory furnaces

The scrap aluminium is separated into a range of categories such as irony aluminium (engine blocks etc.), clean aluminium (alloy wheels). Scraps are classified according to ISRI (Institute of Scrap Recycling Industries).

Depending on the specification of the required ingot casting, it will depend on the type of scrap used in the start melt. Generally, the scrap is charged to a reverberatory furnace (other methods appear to be either less economical and/or dangerous) and melted down to form a "bath". The molten metal is tested using spectroscopy on a sample taken from the melt to determine what refinements are needed to produce the final casts.

After the refinements have been added, the melt may be tested several times to be able to fine-tune the batch to the specific standard.

Once the correct "recipe" of metal is available, the furnace is tapped and poured into ingot moulds, usually via a casting machine. The melt is then left to cool, stacked and sold on as cast silicon–aluminium ingot to various industries for re-use. Mainly, cast alloys like ADC12, LM2, AlSi132, LM24 etc. are produced. These secondary alloys ingots are used in die cast companies.

Tilting rotary furnaces are used for recycling of aluminium scrap, which give higher recovery compared to reverberatory furnaces (Skelner Furnace).

Recycling rates

According to 2020 data from the International Aluminium Institute, the global recycling efficiency rate is 76%. Around 75% of the almost 1.5 billion tonnes of aluminium ever produced is still in productive use today.[31]

Brazil recycles 98.2% of its aluminium can production, equivalent to 14.7 billion beverage cans per year,[32] ranking first in the world, more than Japan's 82.5% recovery rate. Brazil has topped the aluminium can recycling charts eight years in a row.[33]

Europe

Recycling rate for aluminium beverage cans
Country 2018[34]
 Austria 70%
 Belgium 98%
 Bulgaria 81%
 Croatia 80%
 Cyprus 31%
 Czech Republic 47%
 Denmark 88%
 Estonia 75%
 Finland 95%
 France 66%
 Germany 99%
 Greece 55%
 Hungary 33%
 Iceland 87%
 Ireland 73%
 Italy 78%
 Latvia 45%
 Lithuania 96%
 Luxembourg 93%
 Malta 42%
 Netherlands 82%
 Norway 95%
 Poland 80%
 Portugal 43%
 Romania 38%
 Slovakia 75%
 Slovenia 71%
 Spain 70%
 Sweden 86%
  Switzerland 94%
 United Kingdom 75%

Challenges

Aside from recycled aluminium beverage cans, the majority of recycled aluminium comes mixture of different alloys. Those alloys generally have high percentages of silicon (Si) and require additional refinement during the shredding, sorting, and refining process to reduce impurities. Due to the levels of impurities found after refinement, the applications of recycled aluminium alloys are limited to castings and extrusions. The aerospace industry often restrict impurity levels of Si and Fe in alloys to a 0.40% maximum. Controlling the appearance of these elements is increasingly difficult the more often the metal has be recycled and require higher cost operations for the alloys to meet performance requirements.[35]

Byproducts

Main article: Aluminium dross recycling

White dross, a residue from primary aluminium production and secondary recycling operations, usually classified as waste,[36] still contains useful quantities of aluminium which can be extracted industrially.[37] The process produces aluminium billets, together with a highly complex waste material. This waste is difficult to manage. It reacts with water, releasing a mixture of gases (including, among others, hydrogen, acetylene, and ammonia) which spontaneously ignites on contact with air;[38] contact with damp air results in the release of copious quantities of ammonia gas. Despite these difficulties, however, the waste has found use as a filler in asphalt and concrete.[39]

See also

References

  1. ^ "Aluminum Scrap - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2022-06-09.
  2. ^ Wallace, G. (2011-01-01), Lumley, Roger (ed.), "4 - Production of secondary aluminium", Fundamentals of Aluminium Metallurgy, Woodhead Publishing Series in Metals and Surface Engineering, Woodhead Publishing, pp. 70–82, ISBN 978-1-84569-654-2, retrieved 2023-07-30
  3. ^ "Aluminum Recycling". American Chemical Society. Retrieved 2022-06-09.
  4. ^ "Bauxite 101 | The Aluminum Association". www.aluminum.org. Retrieved 2022-06-09.
  5. ^ "The price of virtue". The Economist. 7 June 2007.
  6. ^ minerals.usgs.gov
  7. ^ EPA. "Common Wastes & Material". Retrieved 27 April 2012.
  8. ^ Kvande, Halvor (2008-08-01). "Two hundred years of aluminum ... or is it aluminium?". JOM. 60 (8): 23–24. doi:10.1007/s11837-008-0102-3. ISSN 1543-1851.
  9. ^ Reverdy, Michel; Potocnik, Vinko (2020). "History of Inventions and Innovations for Aluminum Production". TMS 2020 149th Annual Meeting & Exhibition Supplemental Proceedings. The Minerals, Metals & Materials Series. Cham: Springer International Publishing: 1895–1910. doi:10.1007/978-3-030-36296-6_175. ISBN 978-3-030-36296-6.
  10. ^ Habashi, Fathi. "Bayer's process process for Alumina Production: A Historical Perspective" (PDF). Bull. Hist. Chem. {{cite journal}}: line feed character in |title= at position 61 (help)
  11. ^ Byers, Ann (2017-12-15). Reuse It: The History of Modern Recycling. Cavendish Square Publishing, LLC. ISBN 978-1-5026-3127-5.
  12. ^ Byers, Ann (2017-12-15). Reuse It: The History of Modern Recycling. Cavendish Square Publishing, LLC. ISBN 978-1-5026-3127-5.
  13. ^ AG, interstruct. "Aluminium Recycling – Développement durable". recycling.world-aluminium.org. Retrieved 2018-10-26.
  14. ^ "International Aluminum Institute" (PDF). Archived from the original (PDF) on 2022-04-23. Retrieved 2010-02-09.
  15. ^ Aluminum: The Element of Sustainability A North American Aluminum Industry Sustainability Report (PDF) (Report). The Aluminum Association. September 2011. Archived from the original (PDF) on 2021-10-17. Retrieved 2017-09-20.
  16. ^ "Manufacturing with Die Casting: An Eco-Friendly Option". NADCA Design. 2017-01-21. Archived from the original on 2022-10-07. Retrieved 2017-03-08.
  17. ^ Khaji, Khalil; Al Qassemi, Mohammed (2016). "The Role of Anode Manufacturing Processes in Net Carbon Consumption". Metals. 6 (6): 128. doi:10.3390/met6060128.
  18. ^ Clemence, Christopher (April 2, 2019). "Leaders Emerge In The Aluminium Industry's Race To Zero Carbon". Aluminium Insider.
  19. ^ "Aluminium organisation: Environmental issues". Archived from the original on 2010-10-06. Retrieved 2010-11-28.
  20. ^ "Why addressing the aluminium industry's carbon footprint is key". World Economic Forum. 2020-11-30. Retrieved 2023-11-06.
  21. ^ Reinsch, William Alan; Benson, Emily (2022-02-25). "Decarbonizing Aluminum: Rolling Out a More Sustainable Sector". {{cite journal}}: Cite journal requires |journal= (help)
  22. ^ "Aluminum Can Life Cycle Assessment Report Overview" (PDF). 2021.{{cite web}}: CS1 maint: url-status (link)
  23. ^ Reinsch, William Alan; Benson, Emily (2022-02-25). "Decarbonizing Aluminum: Rolling Out a More Sustainable Sector". {{cite journal}}: Cite journal requires |journal= (help)
  24. ^ "Recycling Economic Information (REI) Report". EPA United States Environmental Protection Agency. August 4, 2023. Retrieved November 6, 2023.{{cite web}}: CS1 maint: url-status (link)
  25. ^ Rajeev, Vikram (2021-08-10). "Economic Benefits and Circular Economy Leads to Rising Popularity of Aluminum Recycling in APAC". Frost & Sullivan. Retrieved 2023-11-06.
  26. ^ "Which country is leading the circular economy shift?". www.ellenmacarthurfoundation.org. 2021-06-28. Retrieved 2023-11-06.
  27. ^ "aluminum.org: How Is An Aluminum Can Recycled?". Archived from the original on 2008-05-18. Retrieved 2006-06-06.
  28. ^ www.metalwebnews.com: Melting Practice
  29. ^ "Aluminum and Aluminum Alloys Casting Problems". key-to-metals.com.
  30. ^ Alcoa Primary Aluminum - North America: Products
  31. ^ "Aluminium Recycling Factsheet". International Aluminium Institute. October 2022. Retrieved 14 September 2022.
  32. ^ "In 2009, Brazil was, once again, the leading country worldwide in the collection of aluminium beverage cans, with a recycling rate of 98.2%". Alu - Aluminium for future generations. 2010. Retrieved 2013-03-26.
  33. ^ "Brazil's unemployed catadores keep recycling rates high while earning much-needed cash. - Free Online Library". Thefreelibrary.com. 2010-03-22. Retrieved 2012-11-15.
  34. ^ "Aluminium beverage can recycling in Europe hits record 76.1% in 2018". metalpackagingeurope.org. Retrieved 20 March 2023.
  35. ^ Das, Subodh K (2006). "Emerging Trends in Aluminum Recycling: Reasons and Responses" (PDF). Light Metals 2006. TMS (The Minerals, Metals & Materials Society).
  36. ^ "Residues from aluminium dross recycling in cement" (PDF). Archived from the original (PDF) on 2018-08-26. Retrieved 2018-06-07.
  37. ^ Hwang, J.Y., Huang, X., Xu, Z. (2006), Recovery of Metals from Aluminum Dross and Salt cake, Journal of Minerals & Materials Characterization & Engineering. Vol. 5, No. 1, pp 47-62
  38. ^ "Why are dross & saltcake a concern?". Archived from the original on 2018-06-12. Retrieved 2012-01-13.
  39. ^ Dunster, A.M., Moulinier, F., Abbott, B., Conroy, A., Adams, K., Widyatmoko, D.(2005). Added value of using new industrial waste streams as secondary aggregates in both concrete and asphalt. DTI/WRAP Aggregates Research Programme STBF 13/15C. The Waste and Resources Action Programme
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