Metal Extraction

Metal Extraction

Ores

- Naturally occurring source of metal (minerals) : geological activity / meteorites

- Metal can be economically extracted from (high % minerals)

Open Ended

Why does gold ore contain pure gold but copper ore doesn't?

Minerals

an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes

So, why is this the case?

Gold ore : element

Copper ore : compound

Different Reactivity of Metals

By knowing the metal reactivity, we can...

decide a suitable method to extract the metal.

Gold

- Least reactive

- Panning

Fe, Zn , Al

- Electrolysis

- Reduction by Carbon

Setup for Aluminium extraction by electrolysis.

Extraction of Aluminium

• Al is more reactive than C in the reactivity series.

• Ore : Bauxite

• Main composition : Al₂O₃

Extraction of Aluminium

• Al is more reactive than C in the reactivity series.

• Ore : Bauxite

• Main composition : Al₂O₃

Extraction of Aluminium

• Step 1 : mining (Hall-Héroult process)

• Step 2 : purification (Bauxite to Al₂O₃)

• Step 3 : Electrolysis

Extraction of Aluminium

• Step 3 : Electrolysis

• Al₂O₃ dissolved in molten cryolite

• Reduce melting point of Al₂O₃

• Increase conductivity of the electrolytic cell

Open Ended

Solve the half equations given.

Extraction of iron

Reduction by Carbon

Why?

- Fe is less reactive than C

Blast furnace

- Iron ore (Hematite) : Fe₂O₃

- Coke (carbon)

- Hot air

- Limestone (CaCO₃) : Remove impurities

Extraction of zinc

• Ore : Zinc blende (ZnS)

• Step 1 : Roast in air : ZnS → ZnO & SO₂

• Step 2 : Reduction of ZnO to Zn using C

Open Ended

Why limestone is added to the blast furnace?

Open Ended

Write an equation for the reduction of iron (III) oxide.

Open Ended

Write an equation for the reduction of iron (III) oxide.

Open Ended

Why cryolite is added to the electrolytic cell for the extraction of Aluminium?

Open Ended

Why do the anodes need replacing regularly? Include a chemical equation to explain what happen at the anode.

Open Ended

Write an equation for the reaction at the cathode.