Aluminium dross recycling

Aluminium dross, a byproduct of the aluminium smelting process, can be mechanically recycled to separate the residual aluminium metal from the aluminium oxide.[1][2]

Aluminium dross

Thermo-mechanical metal extraction

The mechanical process of recycling does not use any toxic chemicals previously used in the process of extracting the valuable aluminium in the dross.[3]

Hot dross processing is a system whereby the majority of metal is recovered without chemically reducing the aluminium oxides. The dross is first crushed then separated into aluminium metal rich particles and aluminium oxide rich particles based on density. The metal rich particles are then melted in a furnace to remove the remaining oxide particles.

Mechanical extraction vs chemical

The recovery of aluminium metal from dross has traditionally caused severe environmental issue with highly alkaline waste waters, a waste product that is rich in waste flux and that evolves ammonia gas on contact with water and can spontaneously combust if allowed to get wet [4] A novel method developed in New Zealand claims to be an environmentally sensitive method, and is not toxic and different from previous methods which resulted in a concentrated highly toxic salt cake residue.[5]

An example of a recycling facility

An operating aluminium dross recycling plant (news coverage) https://www.youtube.com/watch?v=t_z8jlDgdCU[6][7][8]

Products that can be made with the residual

A variety of products can be made from the residual aluminium dross after it is recycled into aluminium oxide. See more information on aluminium oxide.[9] Aluminium oxide has a variety of industrial uses which includes being used in paint, dye, concrete, explosives, and fertilizer.[9][10][11]

Dross recycling is different

Aluminium dross recycling is a completely different process to strictly aluminium recycling. Aluminium recycling is where pure aluminium metal products (previously used in another form) are re-melted into aluminium ingots and then re-used to new aluminium products.[12] While aluminium dross recycling is where the dross, a byproduct of the smelting process in the creation of aluminium from bauxite, can be mechanically recycled thus separating the residual aluminium metal from the aluminium oxide.[13]

References
  1. "Institute of Materials Processing (IMP) | Materials Science & Engineering" (PDF). Imp.mtu.edu. Retrieved 2014-06-09.
  2. "Taha Ons Dross Recycling Facility in New Zealand". Azom.com. 2011-10-26. Retrieved 2014-06-09.
  3. "New Aluminium Dross Recycling Facility in New Zealand". Waste Management World. 2011-10-27. Archived from the original on 2012-05-30. Retrieved 2014-06-09.
  4. Mahinroosta, Mostafa; Allahverdi, Ali (26 Jun 2018). "Hazardous aluminum dross characterization and recycling strategies: A critical review". Journal of Environmental Management. 223 (223): 452–468. doi:10.1016/j.jenvman.2018.06.068. PMID 29957419. S2CID 49589263.
  5. "Dross Processing". Aluminum Recycling. Archive.is. 2006-09-26. pp. 193–208. doi:10.1201/9781420006247.ch13. ISBN 978-0-8493-9662-5. Archived from the original on 2012-12-09. Retrieved 2014-06-09.
  6. Scot Mackay (2011-10-06). "Taha Asia Pacific Recycling Plant Opens At Tiwai". Stuff.co.nz. Retrieved 2014-06-09.
  7. "Dross Recycling Plant - Taha Asia Pacific in New Zealand". YouTube. Retrieved 2014-06-09.
  8. "Centre a welcome relief". Stuff.co.nz. 2011-10-13. Retrieved 2014-06-09.
  9. Aluminium oxide
  10. "Aluminum Oxide". Aluminumsulfate.net. Archived from the original on 2016-12-07. Retrieved 2014-06-09.
  11. cf Thermite
  12. cf Aluminium recycling
  13. "Archived copy" (PDF). Archived from the original (PDF) on 2018-01-27. Retrieved 2012-04-14.{{cite web}}: CS1 maint: archived copy as title (link)
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