Like many metals, aluminum is a very useful element.
It is found in rock as bauxite, which is an aluminum ore containing oxygen.
The oxygen has to be removed before the aluminum can be used.
The oxygen and the aluminum are joined so firmly that ordinary smelting does not remove the oxygen as it does with other metals.
The best way to separate the aluminum and the oxygen is to pass electricity through them.
This is called electrolysis.
First of all, rock and sandy particles are removed from the aluminum ore.
This leaves a white powder called aluminum oxide.
It is made up of aluminum atoms joined to oxygen atoms.
The powder is dissolved in a tank of chemicals and heated to about 1742 °F (950 °C).
This makes the aluminum oxide melt and become a liquid.
Molten aluminum collects at the bottom of the tank.
Any impurities in the aluminum collect at the top, where the aluminum oxide cools to form a crust.
Rods made of carbon are lowered into the molten aluminum oxide.
An electric current flows through the molten liquid.
The current enters the liquid through one of the rods and leaves through the carbon lining of the tank.
As this happens, the current breaks up the molten aluminum oxide into aluminum and oxygen.
The molten aluminum metal sinks to the bottom of the tank, and the oxygen combines with the carbon, to be released as carbon dioxide gas.
The pure, molten aluminum is drawn off into a crucible and then poured into molds to cool.
The cool aluminum hardens into ingots.
It is found in rock as bauxite, which is an aluminum ore containing oxygen.
The oxygen has to be removed before the aluminum can be used.
The oxygen and the aluminum are joined so firmly that ordinary smelting does not remove the oxygen as it does with other metals.
The best way to separate the aluminum and the oxygen is to pass electricity through them.
This is called electrolysis.
This leaves a white powder called aluminum oxide.
It is made up of aluminum atoms joined to oxygen atoms.
The powder is dissolved in a tank of chemicals and heated to about 1742 °F (950 °C).
This makes the aluminum oxide melt and become a liquid.
Molten aluminum collects at the bottom of the tank.
Any impurities in the aluminum collect at the top, where the aluminum oxide cools to form a crust.
Rods made of carbon are lowered into the molten aluminum oxide.
An electric current flows through the molten liquid.
The current enters the liquid through one of the rods and leaves through the carbon lining of the tank.
As this happens, the current breaks up the molten aluminum oxide into aluminum and oxygen.
The molten aluminum metal sinks to the bottom of the tank, and the oxygen combines with the carbon, to be released as carbon dioxide gas.
The pure, molten aluminum is drawn off into a crucible and then poured into molds to cool.
The cool aluminum hardens into ingots.
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