Reducing the Temperature of the Hall-Héroult Process

  • Thread starter Thread starter christian everett
  • Start date Start date
  • Tags Tags
    Process Temperature
Click For Summary
SUMMARY

The discussion centers on the potential of using lithium aluminum fluoride (Li3AlF6) as a solvent in the Hall-Héroult process for aluminum smelting, as an alternative to cryolite (Na3AlF6). Li3AlF6 has a lower melting point of 783°C compared to cryolite's melting point of 1,012°C, which could theoretically reduce operational temperatures. However, economic factors heavily influence this consideration, as lithium is significantly more expensive and less abundant than sodium, raising doubts about the feasibility of this substitution in large-scale applications.

PREREQUISITES
  • Understanding of the Hall-Héroult process for aluminum smelting
  • Knowledge of solvent properties, specifically melting points of Li3AlF6 and Na3AlF6
  • Familiarity with economic implications of raw material sourcing in industrial processes
  • Basic chemistry knowledge regarding the solubility of alumina in different solvents
NEXT STEPS
  • Research the solubility of alumina in lithium aluminum fluoride (Li3AlF6)
  • Investigate the economic factors affecting lithium and sodium availability in industrial applications
  • Explore alternative solvents for the Hall-Héroult process and their melting points
  • Study the impact of raw material costs on the feasibility of new aluminum smelting technologies
USEFUL FOR

Chemical engineers, metallurgists, and industrial researchers focused on aluminum production and process optimization will benefit from this discussion.

christian everett
Messages
16
Reaction score
2
I am interested in whether it may be possible to reduce the temperature of the Hall-Héroult process for the electrolytic smelting of aluminum by using Li3AlF6 instead of cryolite (Na3AlF6) as the solvent for the aluminum oxide, and if this might be advantageous over current methods.

Li3AlF6 has a melting point 783°C (1,441.4 °F).

Pure cryolite (Na3AlF6) has a melting point of 1,012 °C (1,854 °F). With a small percentage of alumina (Al2O3) dissolved in it, its melting point drops to about 1,000 °C (1,830 °F). Aluminium fluoride, (AlF3) is added to the mixture to further reduce the melting point.
 
Chemistry news on Phys.org
christian everett said:
I am interested in whether it may be possible to reduce the temperature of the Hall-Héroult process for the electrolytic smelting of aluminum by using Li3AlF6 instead of cryolite (Na3AlF6) as the solvent for the aluminum oxide
Maybe. It depends on how soluble alumina is in lithium aluminum fluoride.
christian everett said:
and if this might be advantageous over current methods.
This is more doubtful. Sodium is far more ubiquitous than lithium, and as a result, the synthetic cryolite used in aluminum refining is cheaper than synthetic lithium aluminum fluoride.

The prevalence of economic considerations in large scale industrial processes shows up from time to time. For instance, the low cost and high abundance of sodium is one reason why researchers are pursuing sodium ion battery technologies to displace lithium technologies.
 
Is there enough cheap lithium available on the market, or is it mostly consumed by the battery industry at the moment?
 
Borek said:
Is there enough cheap lithium available on the market, or is it mostly consumed by the battery industry at the moment?
That’s what I’m doubtful on. A quick search of Alibaba gives NaOH at ~ 500 USD/metric ton, while LiOH is ~ 25 000 USD/metric ton. I’m sure there are industrial ChemE’s on this forum that know the market better than I do. But most of the world’s lithium comes from a few mines in Argentina and Bolivia, whereas sodium is literally everywhere on earth, so it makes sense that there’d be such a price difference even with the focus on Li batteries.