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Materials and Man - Metal Material Recycling

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by

BengLoon Aw

on 9 April 2014

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Transcript of Materials and Man - Metal Material Recycling

Metal Recycling Materials
Three Recycling Techniques
Using Molten Magnesium.
Molten Magnesium
Recycled Magnets from electronics waste are broken into small pieces.
Conclusion
Separation Of Metals.
Selective Precipitation
Electro Slag Refining
They are soaked in molten Magnesium where
Neodymium will diffuse out of the magnets
The mixture is move else where and Magnesium is being vaporized, Leaving behind Neodymium.
Strong Magnets are used in electronics and they are laced with Neodymium.
Selective Precipitation
Add HCl
Add NaOH
Add Oxalic Acids
Remove the Precipitates
To dissolve all metal scraps
To precipitates common metals
Rare earth metal have different solubilities. By controlling the amount of oxalic acids added, specific rare earth metals can be selectively precipitated.
The precipitates are removed and then further treated to reduce them into their metallic forms.
Electro Slag Refining
Example: Copper, Iron, Aluminium
Limitation
Electro Slag Refining can only refine Rare earth metal alloys for future reuse but cannot isolate rare earth metals itself.
Extracting Rare Earth from Scrap Metals using molten magnesium is promising but many rare earths are used in minute amounts.
Rare earth metals are extracted as oxides
through aqueous method. It is expensive to
reduce the oxides into Metallic form
They have to be separated and recycled individually
Using Magnets
Eddy Current
Separation
By Floatation
All kinds of metals are collected from Scraped metal.
Ferrous Metals like Iron are removed by magnets
Fast changing Magnetic Flux Gives different materials different energy based on their electrical conductivity. They are thrown off at different trajectories
Melting Furnace.
Nichrome.
Zirconium Dioxide
- Zirconium Dioxide is chemically stable.

- Zirconium Dioxide ceramics have very high melting point of 2715 degrees Celsius.
- Ziconium Dioxide ceramics have very low thermal conductivity.
Will not react with molten metals
or oxygen at high temperaure.
Can withstand very high temperature
for long period of time.
Prevent heat from Molten metal
from damaging furnace.
to recycle rare earth metals
Introduction Video
Different density fluid are used to phase out materials based on their density.

Graph of resistivity against Chromium Composition
- Demand for Metal will increase over time due to metals being widely used.
- Metals, however are finite resources. It's even more important now to make recycling more efficient.
Acknowledgment.
Video done by
Foong Wee Kit
Li Ying
Slides done by
Ong Chee Hao
Aw Beng Loon
Notes done by
Tang Kai Wen
Full transcript