Aluminum re-smelting and casting

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Introduction

While aluminum scrap contains many impurities, it can be re-smelted and casted to save up to 95% of the energy cost of production from a raw source of bauxite. Although small proportions of used aluminum are generated through household scrap, large amounts of scrap aluminum are collected through building demolition and car dismantling. After the scrap is collected, it is removed of oil and grease, shredded, crushed, dried, and decoated. [1] Scraps of aluminum are sorted based on differing alloy compositions before they are melted in furnaces. Scrap melting is then conducted in furnaces with temperatures up to and upwards of 700 Celsius. Salt fluxes are added to molten aluminum to prevent metal oxidization and remove impurities. After it is melted, molten aluminum is de-gassed and mixed with desired alloys. Finally, the molten metal is put through a casting machine to produce slabs or blocks of aluminum called ingots, or into crucibles for liquid aluminum. [2]

Aluminum Smelting

Summary of Hazards

Physical Hazards

1. Extreme heat exposure in furnaces

2. Limb entrapment in machines used for crushing and shredding

3. Bright lights in furnaces

4. Loud noise

Ergonomic Hazards

1. Repetitive strain from factory work

Chemical Hazards

1. High temperature gas exposure

2. Toxic gas poisoning from melting aluminum

References

  1. Aluminum Association. (2013). The Environmental Footprint of Semi-Finished Aluminum Products in North America. A life cycle assessment report. Retrieved from <http://www.aluminum.org/sites/default/files/LCA_Report_Aluminum_Association_12_13.pdf>.
  2. Aluminum for Future Generations. (n.d.). Aluminium scrap . Retrieved from <http://recycling.world-aluminium.org/resources/processes/>.