Download Extracting Of Other Metals

EXTRACTING METALS FROM
THEIR ORES
CONTENTS
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What Are Ores ?
Metal Ores
How To Extract Metals From Ores ?
Reduction Of Metal Ores
Effects On Environment
WHAT ARE ORES ?
• An ore is any naturallyoccurring source of a metal
that you can economically
extract the metal from.
• Aluminium, for example, is
the most common metal in
the Earth's crust, occurring in
all sorts of minerals.
An Ore
METAL ORES
• Metals are usually found in ores
containing mineral.
• They are combined with Oxygen or
Sulphur to form Oxides or Sulphides.
• Sulphide Ores are converted to
Oxides by heating them in air (called
roasting)
• Eg : Zinc Sulphide to Zinc Oxide
Zinc
Sulphide
Oxygen
Zinc
Oxide
ZnS (s)
1 ½ O2 (g)
ZnO (s)
Sulphur
Dioxide
SO2 (g)
HOW TO EXTRACT METALS FROM
ORES ?
• To obtain a metal , it’s ore , a reducing
agent is used to remove the Oxygen , in
a reduction reaction .
• Examples of some reducing agents :
An impure form of
carbon
Made from
Methane and
Water
REDUCTION OF METAL ORES
• Iron , Manganese And Copper
 Carbon and Carbon monoxide
are
the reducing agents in
the extraction of Fe , Mn & Cu
 These are cheap because coke
can be used which is cheaply
produced by heating coal in
absence of air
 Extraction of Iron is done in a
blast furnace which reaches
temperatures of 2000K
Haematite
Fe2O3(s)
Carbon
Monoxide
3CO (g)
Iron
2Fe(I)
Carbon
Dioxide
3 CO2
Manganese is produced by the
reduction of its Oxide with Carbon.
2MnO(s)
C(s)
2MnI(s)
CO2(g)
 Copper used to be produced this way but
nowadays some ores are converted into
solutions containing Cu2+ ions.
 The copper is extracted by reducing with
scrap iron
 This is “greener” as no CO2 is produced
and scrap iron is cheap and readily
available
 Also , solution can be made from low
grade ore so it is readily available
• Extracting Of Other Metals
 Some metals can’t be extracted using
carbon reduction such as Aluminium ,
Titanium , and Tungsten.
 Aluminium cannot be extracted because it is
more reactive than carbon.
 Titanium and Tungsten also can’t be
extracted using carbon because they will
form a metal carbide which would make the
metal brittle.
• Extraction Of Aluminium
 Aluminium is extracted from purified
bauxite ore (mainly Al2O3)
 Al2O3 is dissolved in molten cryolite ,
which forms a solution which melts at
around 1240K (Al2O3 melts at 2435K)
 Therefore less energy is required
 Aluminium is produced at the negative
electrode
 Oxygen is produced at the positive
electrode
 This gives us an equation :
Al2O3(I)
2Al(I)
1 ½ O(g)
• Extraction Of Titanium
 As Titanium can’t be reduced by
Carbon it is reduced by Sodium or
Magnesium.
 It is an expensive process as Titanium
Oxide is first converted to Titanium
Chloride by reacting it with coke and
Chlorine at 1173K
 Titanium Chloride is then reduced by
Sodium or Magnesium into Titanium
under an inert argon atmosphere at
1300K
• Extraction Of Tungsten
 Tungsten is extracted from it’s Oxide ,
WO3 by reduction with H2 at high temp.
 However , there is some risk as H2 is a
flammable gas , so using it as a
reducing agent is a last resort
EFFECTS ON ENVIRONMENT
• Recycling scrap metals has many
environmental and economic
advantage.
• It reduces the amount of scrap metal in
landfill and it has already been
extracted from its ore so energy is not
required again.
THANK
YOU