Metals
What are the steps in aluminum smelting?
Answered by
Discovery Channel
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Discovery Channel
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It was in February 1886 that American chemist Charles Martin Hall stumbled upon the right formula to transform alumina into aluminum. Hall's technique, which was patented in 1889, involves the following steps:
- Alumina is dissolved in molten cryolite, or sodium aluminum fluoride (Na3AlF6), at 1,000 degrees Celsius (1,832 degrees Fahrenheit) to enable electrolysis at lower temperatures.
- This solution, or electrolyte, is placed in a vat lined with graphite.
- Carbon anodes are submerged in the solution.
- Electricity is passed through the electrolyte.
- At the vat, which serves as the cathode, the electric current reduces aluminum ions to aluminum metal. At the anode, carbon is oxidized into carbon dioxide (CO2).
- The liquid aluminum metal sinks to the bottom of the vat, which is drained periodically.
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