Aluminium Extraction and Uses Aluminium Mining Aluminium Ore

Aluminium Extraction and Uses

Aluminium Mining • Aluminium Ore is called Bauxite. • Bauxite is a red mineral made of aluminium oxide and iron oxides. • Bauxite is mined in various places, e. g. Russia, Jamaica

Bauxite Purification • Bauxite is heated with sodium hydroxide. • This dissolves the alumina but not the other minerals. • The residue is filtered off and disposed of. • The filtrate is acidified and heated to produce pure alumina, aluminium oxide powder.

Extracting aluminium • Aluminium is more reactive than carbon. • So carbon will not reduce aluminium oxide. • Aluminium cannot be extracted in a blast furnace. • Aluminium is extracted using electricity in a process called electrolysis.

The electrolysis cell

How it works Direct Current Al 2 O 3 Anode + Al 3+ O 2 - O 2 O 2 - Al 3+ Cathode - O 2 Al 3+ O 2 O 2 - 2 Al 3+ + 3 O 2 -

At the anode 2 -- e e. O O- 2 ee O 2 - anode + positive O 2 CO 2 O 2 O e-2 -e. O-2 ee O 2 - 2 O 2 - O 2 + 4 e- O 2 + C CO 2

At the cathode Al Al 3+ e- e e. Cathode Al 3+ Al Al 3+ + 3 e- Al l iq u id al e- e e- negative

Quick Review Direct Current Anode CO 2 ++ CO 2 Al 3+ O 2 - O 2 O 2 - Al 3+ Cathode - O 2 Al 3+ O 2 O 2 -

At the electrodes. • At the negative cathode • Positive Aluminium ions drift to the cathode. • They gain electrons and become aluminium atoms • Al 3+ + 3 e- Al • At the positive anode • Negative oxide ions drift to the positive anode. • They lose electrons and become oxygen gas molecules. • 2 O 2 - O 2 + 4 e-

Making stuff

Uses of aluminium • • • Power cables Saucepans Aeroplanes Bicycles Cars Battleships Cooking foil Cans Space blankets Statues Window frames • • • Light, unreactive Light, doesn’t rust Light, radar quiet Reflective, unreactive Unreactive Reflective Unreactive