The Chemist says:
The Bayer process isn't the expensive, energy intensive part of aluminum production - the subsequent Hall-Heroult process, by which the alumina obtained
from the Bayer process is electrolyzed in molten cryolite at over 1000 degrees
Celsius is the expensive part.
While it is true that the Hall-Heroult process substantially adds to the expense of the production and refinement of the aluminum metal, the Bayer process remains an expensive component of the separation process. It is most certainly more cost intensive than the extraction of iron from its oxides. Therefore, the original statement remains true, factual, and intact. However, you're absolutely correct in your assertion that the Hall-Heroult process drastically attenuates the overall cost of aluminum refinement.
As far as recycling goes, I see nothing inherent to steel that would make it more complex to recycle than aluminum. It's the same basic process - clean, melt down, re-cast - whether you're talking steel or aluminum. And if nothing else, the magnetic nature of steel would make it easier to separate from other materials, which would aid in the recycling process.
Since the melting point of Iron (Fe) is 1535 C and the melting point of aluminum is 660 C. It becomes quite obvious as to the reason that aluminum is the much preferred recycling material. It takes much more energy to reach 1535 C, than 660 C. Refining aluminum therefore, becomes a much less energy intensive process. Subsequently, reduction of required energy, translates into less cost!
- Slim
