Extraction of Metals
- Created by: emma
- Created on: 06-03-14 21:41
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- Extraction of Metals
- Blast furnace
- Step 1 coke burned in hot air to produce CO2 (endothermic)
- C + O2= CO2
- Step 2 more coke reacts with the CO2
- C + CO2= 2CO
- Step 3 Iron oxide reduced by CO
- Fe2O3 + 3CO = 2Fe + 3CO2
- Fe2O3 + 3C= 2Fe + 3CO
- C cant be used for Al, Ti or W as it produces impurities (more reactive than C)
- Continuous process
- Advantages
- Cheap raw materials
- Continuous process means it can be made effciently
- Endothermic reaction keeps vessel hot (less energy needed)
- Disadvantages
- CO2 is released
- metals which react with carbon to form carbides cannot be extracted
- Metals are not that pure
- Step 1 coke burned in hot air to produce CO2 (endothermic)
- Low grade copper ores
- convert copper compounds into aqueous form
- using dilute H2S04 and a specialized bacterium
- Then react with scrap iron
- using dilute H2S04 and a specialized bacterium
- Cu(2+) + Fe(s)= Cu(s) +Fe(2+aq)
- Advantages
- little energy
- Works on low grade copper ores including mining waste
- Iron is much cheaper than copper
- convert copper compounds into aqueous form
- Electrolysis
- Al must be molten to conduct electricity
- Dissolved in molten cryolite requires a lower temperature 900
- Extraction of Al is a continuous process
- Electrodes are made of graphite
- 2AlO3=4Al + 3O2
- Negative electrode Al(3+) + 3e- = Al
- Positive electrode 2O(2-)= O2 + 4e-
- Burns due to O2 produced C(s) + O2(g) = CO2(g)
- Advantages
- Continuous process so efficient
- Makes pure A;
- Disadvantages
- high energy cost of electric and melting Al
- Only works for ionic oxides
- Al must be molten to conduct electricity
- Extraction of Ti using more reactive metal
- Batch process
- Step 1 TiO2 + 2Cl2 + 2C = TiCl4 + 2CO at 900 to convert to liquid
- Step 2
- Ar atmosphere to prevent O2 reacting
- Endothermic (1000)
- Advantages
- Produces very pure Ti
- Disasdvantages
- batch proces which adds to cost
- Na/Mg are expensive
- Ar is expensive
- High energy costsrequired
- Roasting
- Metal oxides easier to extract than sulphides
- sulphides converted to oxides by roasting in the air
- 2ZnS(s) + 3O2(g) = 2ZnO(s) + 2SO2(g)
- Produces SO2 which could lead to acid rain
- Or used to make sulphuric acid
- SO2 + H2O +1/2O2 = H2SO4
- Or used to make sulphuric acid
- Extraction of W using H
- WO3 is heated with hydrogen at 900
- Hydrogen is the reducing agent
- WO3 + 3H2 =W +3H2O
- Advantages
- Produces very pure W
- Hydrogen is quite cheap
- Disadvantage
- High energy costs
- Hydrogen is flammable
- Blast furnace
- Burns due to O2 produced C(s) + O2(g) = CO2(g)
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