15/11 Extraction of Metals

• Chemistry
• Secondary Education
• Age 12,13

Extraction of metals

Topic 3 Metals 

15 November 2023

• Describe the ease in obtaining metals from their ores, related to the position of the metal in the reactivity series
• Describe the extraction of iron from hematite in the blast furnace, limited to:
• (a) the burning of carbon (coke) to provide heat and produce carbon dioxide
• (b) the reduction of carbon dioxide to carbon monoxide
• (c) the reduction of iron(III) oxide by carbon monoxide
• (d) the thermal decomposition of calcium carbonate / limestone to produce calcium oxide
• (e) the formation of slag

My Goals Today:

What is a metal ore?

• a rock that contains enough of the metal to make it worthwhile extracting the metal

Relevance of our session

Why is metal extraction important?

• provided us with useful materials to make tools, weapons, buildings, bridges and aeroplanes

What native metals can we find in the earth's crust?

• gold
• silver

Many of the useful metals such as iron and aluminium are locked up in ores.

Discussion Forum

• How can we extract the valuable metal from its oxide ore?
• What reaction needs to take place?
• What extraction methods are necessary for the extraction of iron and aluminium metals?

Extraction of metals

Topic 3 Metals 

15 November 2023

Review

• When metals react with oxygen, a metal oxide is formed, for example:

iron + oxygen → iron(III) oxide 

4Fe (s) + 3O2 (g) → 2Fe2O3 (s)

Key Terms

• Hematite - the main ore of iron, in the form of impure iron(III)oxide
• Bauxite - the main ore of aluminium, in the form of impure aluminium oxide
• Reduction - the removal of oxide from an oxide
• Electrolysis - splitting with electricity

Methods of Metal Extraction

• More reactive metals are extracted by electrolysis. The electrolytic extraction of metals consumes large amounts of electricity, which is reflected in the cost of the metal.

Extraction of Iron from Hematite

• Zone 1 - Coke burns in the hot air, forming carbon dioxide 
• The reaction is exothermic, so it gives off heat, heating the furnace.

• Iron is extracted in a large container called a blast furnace from its ore, hematit.
• Modern blast furnaces produce approximately 10,000 tonnes of iron per day.

Extraction of Iron from Hematite

• Zone 2 - At the high temperatures in the furnace, more coke reacts with carbon dioxide, forming carbon monoxide.
• Carbon dioxide has been reduced to carbon monoxide.

Extraction of Iron from Hematite

• Zone 3 - Carbon monoxide reduces the iron(III) oxide in the iron ore to form iron 
• This will melt and collect at the bottom of the furnace, where it is tapped off.

Extraction of Iron from Hematite

• Limestone (calcium carbonate) is added to the furnace to remove impurities in the ore.
• The calcium carbonate in the limestone thermally decomposes to form calcium oxide.
• The calcium oxide formed reacts with the silicon dioxide, which is an impurity in the iron ore, to form calcium silicate.

Extraction of Iron from Hematite

• This melts and collects as a molten slag floating on top of the molten iron, which is tapped off separately.

Extraction of Iron from Hematite

T O  D O:

• Listen carefully to Mr. Russel's instructions.
• Complete the activity in your notebook.

ACTIVITY 01

• The diagram shows a blast furnace.
• The following equations represent reactions which take place in the blast furnace.

ACTIVITY 01

1. Arrange the equations in the correct zoning order in a flow chart.
2. Which reaction is used to increase the temperature inside the blast furnace? 
3. Which reaction is an example of thermal decomposition? 
4. In which reaction is carbon both oxidised and reduced? 
5. Which equation shows the removal of an impurity from the iron? 

Type two things you learned today.