Where do metals come from?

1
Where do metals come from?
2
objectives

• Most metals are found as chemical compounds
  (minerals) in rocks
• Rocks containing significant amount of
  particular minerals are called ores
• How a metal is extracted from its ore depends on
  that metals position in the reactivity series
• To some extent our human history is closely tied
  to the history of metal extraction

3
Much metal around?
4
Much metal around?
5
How easily a metal can be obtained depends on its
reactivity
potassium
sodium
lithium
calcium
magnesium
aluminium
zinc
iron
lead
copper
silver
gold
6
(No Transcript)
7
Gold is so unreactive that it can be found
native in the ground
8
Silver is also to be found in metallic form but
you cant really pan for silver, its mined
9
Europe always had a lot of silver mines so it
developed an economy based on silver coins
10
The blue colour is caused by the mineral copper
carbonate
11
Copper, or bronze, reacts with CO2 over time to
give a coating of copper carbonate, often called
verdigris
Bronze is an alloy of copper and tin, stronger
than pure copper
12
This is a rock called malachite. It contains
significant amounts of the mineral CuCO3. A rock
containing significant amounts of a metal
compound is called an ore
Malachite is an ore, from which we can extract
copper
13
This ore, cassiterite, contains tin oxide. It is
from this ore that tin is extracted. Tin was
obtained as long ago as copper was, back in an
era of human history known as
14
The Bronze Age From about 2000BC
15
In 776 BC What would be the most valuable
metal? Second most valuable? Third most valuable?
16
Most metals are found as compounds minerals in
rocks. Rocks containing a significant amount of
mineral are called ores. Many metals are
extracted from their ores by heating them with
carbon.
17
Bauxite Al2O3
Haematite Fe2O3
Galena PbS
Cinnabar HgS
Malachite CuCO3
Cassiterite SnO2
Olivine MgSiO4
Sphalerite ZnS
18
Chemistry changes the world (early
example) About 500BC the Iron Age came to
Europe when the techniques of smelting were
learned. Iron ore is heated with charcoal in a
furnace.
Iron is much stronger than bronze, you get
wheels, saws to cut down trees, and stronger
weapons with iron.
19
This rock contains a significant amount of iron
oxide (thats what gives it the rusty colour) It
is often called simply iron ore.
20
Reaction of lead oxide with carbon LEAD OXIDE
CARBON ? LEAD CARBON DIOXIDE PbO2 C ?
Pb CO2
LOST OXYGEN - REDUCTION
GAINED OXYGEN - OXIDATION
21
(No Transcript)
22
The Blast Furnace
2Fe2O3 3C ? 4Fe 3CO2
Iron oxide is reduced by carbon into iron metal