EXTRACTING METALS FROM THEIR ORES

CONTENTS 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 naturally-occurring 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 Sulphur Dioxide ZnO (s) SO2 (g) ZnS (s) 1 ½ O2 (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 : Made from Methane and Water An impure form of carbon

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

Fe2O3(s) Haematite 3CO (g) Carbon Monoxide 2Fe(I) Iron 3 CO2 Carbon Dioxide

Manganese is produced by the reduction of its Oxide with Carbon. 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 2MnO(s) C(s) 2MnI(s) CO2(g)

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.

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