Mixing the tailings of gold and silver ores with a cyanide solution, or simply spraying the tailings with a cyanide solution, would cause a chemical reaction to take place. When gold and silver come in contact with cyanide, they it liquefy. Now the gold-silver-cyanide solution can be drained off and processed further.
Another chemical reaction is put to work to separate the cyanide solution from the liquid gold and silver. Zinc is mixed with this solution, which causes the gold and silver to return to a solid form.
Now there is a solid of gold, silver, and zinc. Yet another chemical reaction is used to remove the zinc. Sulphuric acid dissolves the zinc and leaves just the gold-silver mixture.
From this gold-silver solid, gold and silver are separated by further processing.
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Rabu, 22 April 2009
Rabu, 11 Maret 2009
JEE - Study Guide - 10. Principles and Processes of Extraction of Elements
Sections in the chapter
1. Origin of Elements
2. Distrubution of elements on earth
3. Elements of biological world
4. Ocean as a source of elements
5. Modes of occurrence of metals
6. Occurrence of metal: Minerals and ores
7. Mineral wealth of India
8. Extraction of elements
9. Extraction of nonmetallic elements
10. Extraction of metals: Metallurgy
11. Thermodynamics of metallurgy
Conceptual Questions with Answers:
Additional Numerical Problems for Practice:
Revision Exercises
Very Short Answer questions
Short Answer Questions
Long Answer Questions
Competition File
Numerical Problems
Objective Questions:
Fill in the blanks:
True or False:
Study Plan
Sections in the chapter
Day 1
1. Origin of Elements
2. Distrubution of elements on earth
3. Elements of biological world
4. Ocean as a source of elements
Day 2
Practice Problems 10.1 to 10.5
5. Modes of occurrence of metals
6. Occurrence of metal: Minerals and ores
7. Mineral wealth of India
Day 3
8. Extraction of elements
9. Extraction of nonmetallic elements
10. Extraction of metals: Metallurgy
Day 4
10. Contd
Day 5
10 contd.
Day 6
11. Thermodynamics of metallurgy
Conceptual Questions with Answers: 1 to 14
Day 7
Revision Exercises
Very Short Answer questions 1 to 20
Short Answer Questions 1 to 35
Day 8
Competition File
Objective Questions: 1 to 24
Fill in the blanks: 1 to 6
True or False: 1 to 10
Day 9
Revision extraction of metals
Day 10
Revision of rest of the chapter
Days 11 to 20
Revision and test paper question solving
1. Origin of Elements
2. Distrubution of elements on earth
3. Elements of biological world
4. Ocean as a source of elements
5. Modes of occurrence of metals
6. Occurrence of metal: Minerals and ores
7. Mineral wealth of India
8. Extraction of elements
9. Extraction of nonmetallic elements
10. Extraction of metals: Metallurgy
11. Thermodynamics of metallurgy
Conceptual Questions with Answers:
Additional Numerical Problems for Practice:
Revision Exercises
Very Short Answer questions
Short Answer Questions
Long Answer Questions
Competition File
Numerical Problems
Objective Questions:
Fill in the blanks:
True or False:
Study Plan
Sections in the chapter
Day 1
1. Origin of Elements
2. Distrubution of elements on earth
3. Elements of biological world
4. Ocean as a source of elements
Day 2
Practice Problems 10.1 to 10.5
5. Modes of occurrence of metals
6. Occurrence of metal: Minerals and ores
7. Mineral wealth of India
Day 3
8. Extraction of elements
9. Extraction of nonmetallic elements
10. Extraction of metals: Metallurgy
Day 4
10. Contd
Day 5
10 contd.
Day 6
11. Thermodynamics of metallurgy
Conceptual Questions with Answers: 1 to 14
Day 7
Revision Exercises
Very Short Answer questions 1 to 20
Short Answer Questions 1 to 35
Day 8
Competition File
Objective Questions: 1 to 24
Fill in the blanks: 1 to 6
True or False: 1 to 10
Day 9
Revision extraction of metals
Day 10
Revision of rest of the chapter
Days 11 to 20
Revision and test paper question solving
Minggu, 28 Desember 2008
Extractive metallurgy- Study Guide - IIT JEE
Chemical principles and reactions only (industrial details excluded);
Carbon reduction method (iron and tin);
Self reduction method (copper and lead);
Electrolytic reduction method (magnesium and aluminium);
Cyanide process (silver and gold).
Carbon reduction method (iron and tin);
Self reduction method (copper and lead);
Electrolytic reduction method (magnesium and aluminium);
Cyanide process (silver and gold).
Selasa, 05 Februari 2008
Revision Ch 17. Extractive Metallury - Ores
Syllabus
Ores and minerals: Commonly occurring ores and minerals of
iron,
copper,
tin,
lead,
magnesium,
aluminium,
zinc and
silver.
Extractive metallurgy: Chemical principles and reactions only (industrial details excluded);
Carbon reduction method (iron and tin);
Self reduction method (copper and lead);
Electrolytic reduction method (magnesium and aluminium);
Cyanide process (silver and gold).
Ores and minerals of iron
Magnetite
Haematite
Limonite
Iron Pyrites
Copper Pyrites
Haematite is the principal ore.
Ores and minerals of Tin
Tin stone
Ores and minerals of Copper
Copper pyrites
Malachanite
Cuprite or ruby copper
Azurite
Copper glance
Minerals of Lead
Galena
Cerussite
Anglesite
Wulfenite
Stolzite
Minerals of Magnesium
Magnesite
Carnallite
Kiesserite
Schonite
Dolomite
Epsomite
kainite
Minerals of Alumium
Corundum
Diaspore
Bauxite
Cryolite
Feldspar, Mica, Kaolinite
Alunite or Alumstone
Turquoise
Aluminates of Magensium, Iron and Manganese
Minerals of Silver
Argentite
Pyrargarite
Proustite
Horn Silver
Minerals of Zinc
(from X book by Viraf Dalal)
Zincite
Calamine
Zinc Blende
Minerals of Gold
Mainly native gold
Nagyagite
Calaverite
Sylvanite
Krennerite
Ores and minerals: Commonly occurring ores and minerals of
iron,
copper,
tin,
lead,
magnesium,
aluminium,
zinc and
silver.
Extractive metallurgy: Chemical principles and reactions only (industrial details excluded);
Carbon reduction method (iron and tin);
Self reduction method (copper and lead);
Electrolytic reduction method (magnesium and aluminium);
Cyanide process (silver and gold).
Ores and minerals of iron
Magnetite
Haematite
Limonite
Iron Pyrites
Copper Pyrites
Haematite is the principal ore.
Ores and minerals of Tin
Tin stone
Ores and minerals of Copper
Copper pyrites
Malachanite
Cuprite or ruby copper
Azurite
Copper glance
Minerals of Lead
Galena
Cerussite
Anglesite
Wulfenite
Stolzite
Minerals of Magnesium
Magnesite
Carnallite
Kiesserite
Schonite
Dolomite
Epsomite
kainite
Minerals of Alumium
Corundum
Diaspore
Bauxite
Cryolite
Feldspar, Mica, Kaolinite
Alunite or Alumstone
Turquoise
Aluminates of Magensium, Iron and Manganese
Minerals of Silver
Argentite
Pyrargarite
Proustite
Horn Silver
Minerals of Zinc
(from X book by Viraf Dalal)
Zincite
Calamine
Zinc Blende
Minerals of Gold
Mainly native gold
Nagyagite
Calaverite
Sylvanite
Krennerite
Revision - Carbon reduction method
Fe
The reduction of the ore
At the high temperature at the bottom of the furnace, carbon dioxide reacts with carbon to produce carbon monoxide.
It is the carbon monoxide which is the main reducing agent in the furnace.
Extraction of Tin
The ore is tin stone that contains 10% of the metal as SnO2.
SnO2 + 2C = Sn + 2CO
The moltenmetal is collected from the bottom of the blast furnace.
The metal may be purified elctrolytically
The reduction of the ore
At the high temperature at the bottom of the furnace, carbon dioxide reacts with carbon to produce carbon monoxide.
It is the carbon monoxide which is the main reducing agent in the furnace.
Extraction of Tin
The ore is tin stone that contains 10% of the metal as SnO2.
SnO2 + 2C = Sn + 2CO
The moltenmetal is collected from the bottom of the blast furnace.
The metal may be purified elctrolytically
Revision - Self reduction method
Copper
The concentrated ore is heated strongly with silicon dioxide (silica) and air or oxygen in a furnace or series of furnaces.
The Full Process
Large amount of copper are obtained from copper pyrite (CuFeS2) by smelting. Ores containing 4% or more copper are used and are treated by smelting process.
Concentration - Froth-Floatation process
The finely crushed ore is concentrated by Froth-Floatation process. The finely crushed ore is suspended in water containing a little amount of pine oil. A blast of air is passed through the suspension. The particles get wetted by the oil and float as a froth which is skimmed. The gangue sinks to the bottom.
Roasting
The concentrated ore is then roasted in a furnace in the presence of a current of air. Sulphur is oxidized to SO2 and impurities of arsenous and antimony are removed as volatile oxides.
The following reaction takes place.
2CuFeS2 + O2 → Cu2S + 2FeS + SO2
S + O2 รจ SO2
4As + 3O2 → As2O3
4Sb + 3O2 → 2Sb2O3
Cuprous sulphide and ferrous sulphide are further oxidized into their oxides.
2Cu2S + 3O2 → 2Cu2O + 2SO2
2FeS + 3O2 → 2FeO + 2SO2
Smelting
The roasted ore is mixed with coke and silica (sand) SiO2 and is introduced in to a blast furnace. The hot air is blasted and FeO is converted in to ferrous silicate (FeSiO3).
FeO + SiO2 → FeSiO3
Cu2 O + FeS → Cu2 S + FeO
FeSiO3 (slag) floats over the molten matte of copper.
Bessemerization
Copper metal is extracted from molten matte through bessemerization . The matte is introduced in to Bessemer converter which uphold by tuyers. The air is blown through the molten matte. Blast of air converts Cu2S partly into Cu2O which reacts with remaining Cu2S to give molten copper.
2Cu2 S + 3O2 → 2Cu2 O + 2SO2
2Cu2O + Cu2 S → 6Cu + SO2
The copper so obtained is called "Blister copper" because, as it solidifies, SO2 hidden in it escapes out producing blister on its surface.
Removal of impurities from blister copper
Blister copper is 99% pure. It contains impurities mainly iron but little amount of As, Zn, Pb, Ag and Au may also be present. These impurities adversely affect the electrical as well as mechanical properties of copper. Therefore, they must be removed. Refining is used for this purpose.
Refining
Blister copper is refined by electrolysis. Blocks of blister copper are used as anodes and thin sheets of pure copper act as cathodes. The cathode plates are coated with graphite in order to remove depositing copper. The electrolyte is copper sulphate (CuSO4) mixed with a little amount of H2 SO4 to increase the electrical conductivity. Optimum potential difference is 1.3 volt for this electrolytic process. During electrolysis, pure copper is deposited on the cathode plates and impurities which are soluble and fall to the bottom of the cell as anode mud or sludge.
Reactions during electrolysis at electrodes
Cu → Cu+2 + 2e‾ (at the anode)
Cu+2 +2e‾ → Cu (at the cathode)
We get copper is 100% pure copper from electrolytic refining.
The concentrated ore is heated strongly with silicon dioxide (silica) and air or oxygen in a furnace or series of furnaces.
The Full Process
Large amount of copper are obtained from copper pyrite (CuFeS2) by smelting. Ores containing 4% or more copper are used and are treated by smelting process.
Concentration - Froth-Floatation process
The finely crushed ore is concentrated by Froth-Floatation process. The finely crushed ore is suspended in water containing a little amount of pine oil. A blast of air is passed through the suspension. The particles get wetted by the oil and float as a froth which is skimmed. The gangue sinks to the bottom.
Roasting
The concentrated ore is then roasted in a furnace in the presence of a current of air. Sulphur is oxidized to SO2 and impurities of arsenous and antimony are removed as volatile oxides.
The following reaction takes place.
2CuFeS2 + O2 → Cu2S + 2FeS + SO2
S + O2 รจ SO2
4As + 3O2 → As2O3
4Sb + 3O2 → 2Sb2O3
Cuprous sulphide and ferrous sulphide are further oxidized into their oxides.
2Cu2S + 3O2 → 2Cu2O + 2SO2
2FeS + 3O2 → 2FeO + 2SO2
Smelting
The roasted ore is mixed with coke and silica (sand) SiO2 and is introduced in to a blast furnace. The hot air is blasted and FeO is converted in to ferrous silicate (FeSiO3).
FeO + SiO2 → FeSiO3
Cu2 O + FeS → Cu2 S + FeO
FeSiO3 (slag) floats over the molten matte of copper.
Bessemerization
Copper metal is extracted from molten matte through bessemerization . The matte is introduced in to Bessemer converter which uphold by tuyers. The air is blown through the molten matte. Blast of air converts Cu2S partly into Cu2O which reacts with remaining Cu2S to give molten copper.
2Cu2 S + 3O2 → 2Cu2 O + 2SO2
2Cu2O + Cu2 S → 6Cu + SO2
The copper so obtained is called "Blister copper" because, as it solidifies, SO2 hidden in it escapes out producing blister on its surface.
Removal of impurities from blister copper
Blister copper is 99% pure. It contains impurities mainly iron but little amount of As, Zn, Pb, Ag and Au may also be present. These impurities adversely affect the electrical as well as mechanical properties of copper. Therefore, they must be removed. Refining is used for this purpose.
Refining
Blister copper is refined by electrolysis. Blocks of blister copper are used as anodes and thin sheets of pure copper act as cathodes. The cathode plates are coated with graphite in order to remove depositing copper. The electrolyte is copper sulphate (CuSO4) mixed with a little amount of H2 SO4 to increase the electrical conductivity. Optimum potential difference is 1.3 volt for this electrolytic process. During electrolysis, pure copper is deposited on the cathode plates and impurities which are soluble and fall to the bottom of the cell as anode mud or sludge.
Reactions during electrolysis at electrodes
Cu → Cu+2 + 2e‾ (at the anode)
Cu+2 +2e‾ → Cu (at the cathode)
We get copper is 100% pure copper from electrolytic refining.
Revision - Electrolytic reduction method
Electrolysis of magnesium
• Dolomite and seawater is precipitated
as insoluble magnesium hydroxide
Mg(OH)2 which is subsequently treated
with HCl to give MgCl2.
• MgCl2 is fed into electrolysis cell to
produce Mg metal at cathode and Cl2
at anode.
Conversion of the aluminium oxide into aluminium by electrolysis
The aluminium oxide is electrolysed in solution in molten cryolite, Na3AlF6. Cryolite is another aluminium ore, but is rare and expensive, and most is now made chemically.
• Dolomite and seawater is precipitated
as insoluble magnesium hydroxide
Mg(OH)2 which is subsequently treated
with HCl to give MgCl2.
• MgCl2 is fed into electrolysis cell to
produce Mg metal at cathode and Cl2
at anode.
Conversion of the aluminium oxide into aluminium by electrolysis
The aluminium oxide is electrolysed in solution in molten cryolite, Na3AlF6. Cryolite is another aluminium ore, but is rare and expensive, and most is now made chemically.
Revision - Cyanide Process
Gold
It is now the most important and widely used process for extracting gold from ores.
The ore is first finely ground and concentrated by flotation.
To remove certain impurities, it may be roasted.
It is then mixed with a dilute solution of sodium cyanide (or potassium or calcium cyanide) while air is bubbled through it.
Soluble aurocyanide complex ion, Au(CN)-2^-1 is formed .
Silver, usually present as an impurity, also forms a similar soluble ion.
It is now the most important and widely used process for extracting gold from ores.
The ore is first finely ground and concentrated by flotation.
To remove certain impurities, it may be roasted.
It is then mixed with a dilute solution of sodium cyanide (or potassium or calcium cyanide) while air is bubbled through it.
Soluble aurocyanide complex ion, Au(CN)-2^-1 is formed .
Silver, usually present as an impurity, also forms a similar soluble ion.
Kamis, 17 Januari 2008
Ch.17. Ores/Minerals and Extractive Metallury - Core Points for Revision
Syllabus
Ores and minerals: Commonly occurring ores and minerals of
iron,
copper,
tin,
lead,
magnesium,
aluminium,
zinc and
silver.
Extractive metallurgy: Chemical principles and reactions only (industrial details excluded);
Carbon reduction method (iron and tin);
Self reduction method (copper and lead);
Electrolytic reduction method (magnesium and aluminium);
Cyanide process (silver and gold).
Ores and minerals of iron
Magnetite
Haematite
Limonite
Iron Pyrites
Copper Pyrites
Haematite is the principal ore.
Ores and minerals of Tin
Tin stone
Ores and minerals of Copper
Copper pyrites
Malachanite
Cuprite or ruby copper
Azurite
Copper glance
Minerals of Lead
Galena
Cerussite
Anglesite
Wulfenite
Stolzite
Minerals of Magnesium
Magnesite
Carnallite
Kiesserite
Schonite
Dolomite
Epsomite
kainite
Minerals of Alumium
Corundum
Diaspore
Bauxite
Cryolite
Feldspar, Mica, Kaolinite
Alunite or Alumstone
Turquoise
Aluminates of Magensium, Iron and Manganese
Minerals of Silver
Argentite
Pyrargarite
Proustite
Horn Silver
Minerals of Zinc
(from X book by Viraf Dalal)
Zincite
Calamine
Zinc Blende
Minerals of Gold
Mainly native gold
Nagyagite
Calaverite
Sylvanite
Krennerite
Fe
The reduction of the ore
At the high temperature at the bottom of the furnace, carbon dioxide reacts with carbon to produce carbon monoxide.
It is the carbon monoxide which is the main reducing agent in the furnace.
Extraction of Tin
The ore is tin stone that contains 10% of the metal as SnO2.
SnO2 + 2C = Sn + 2CO
The moltenmetal is collected from the bottom of the blast furnace.
The metal may be purified elctrolytically
Copper
The concentrated ore is heated strongly with silicon dioxide (silica) and air or oxygen in a furnace or series of furnaces.
Electrolysis of magnesium
• Dolomite and seawater is precipitated
as insoluble magnesium hydroxide
Mg(OH)2 which is subsequently treated
with HCl to give MgCl2.
• MgCl2 is fed into electrolysis cell to
produce Mg metal at cathode and Cl2
at anode.
Conversion of the aluminium oxide into aluminium by electrolysis
The aluminium oxide is electrolysed in solution in molten cryolite, Na3AlF6. Cryolite is another aluminium ore, but is rare and expensive, and most is now made chemically.
Gold
It is now the most important and widely used process for extracting gold from ores.
The ore is first finely ground and concentrated by flotation.
To remove certain impurities, it may be roasted.
It is then mixed with a dilute solution of sodium cyanide (or potassium or calcium cyanide) while air is bubbled through it.
Soluble aurocyanide complex ion, Au(CN)-2^-1 is formed .
Silver, usually present as an impurity, also forms a similar soluble ion.
Ores and minerals: Commonly occurring ores and minerals of
iron,
copper,
tin,
lead,
magnesium,
aluminium,
zinc and
silver.
Extractive metallurgy: Chemical principles and reactions only (industrial details excluded);
Carbon reduction method (iron and tin);
Self reduction method (copper and lead);
Electrolytic reduction method (magnesium and aluminium);
Cyanide process (silver and gold).
Ores and minerals of iron
Magnetite
Haematite
Limonite
Iron Pyrites
Copper Pyrites
Haematite is the principal ore.
Ores and minerals of Tin
Tin stone
Ores and minerals of Copper
Copper pyrites
Malachanite
Cuprite or ruby copper
Azurite
Copper glance
Minerals of Lead
Galena
Cerussite
Anglesite
Wulfenite
Stolzite
Minerals of Magnesium
Magnesite
Carnallite
Kiesserite
Schonite
Dolomite
Epsomite
kainite
Minerals of Alumium
Corundum
Diaspore
Bauxite
Cryolite
Feldspar, Mica, Kaolinite
Alunite or Alumstone
Turquoise
Aluminates of Magensium, Iron and Manganese
Minerals of Silver
Argentite
Pyrargarite
Proustite
Horn Silver
Minerals of Zinc
(from X book by Viraf Dalal)
Zincite
Calamine
Zinc Blende
Minerals of Gold
Mainly native gold
Nagyagite
Calaverite
Sylvanite
Krennerite
Fe
The reduction of the ore
At the high temperature at the bottom of the furnace, carbon dioxide reacts with carbon to produce carbon monoxide.
It is the carbon monoxide which is the main reducing agent in the furnace.
Extraction of Tin
The ore is tin stone that contains 10% of the metal as SnO2.
SnO2 + 2C = Sn + 2CO
The moltenmetal is collected from the bottom of the blast furnace.
The metal may be purified elctrolytically
Copper
The concentrated ore is heated strongly with silicon dioxide (silica) and air or oxygen in a furnace or series of furnaces.
Electrolysis of magnesium
• Dolomite and seawater is precipitated
as insoluble magnesium hydroxide
Mg(OH)2 which is subsequently treated
with HCl to give MgCl2.
• MgCl2 is fed into electrolysis cell to
produce Mg metal at cathode and Cl2
at anode.
Conversion of the aluminium oxide into aluminium by electrolysis
The aluminium oxide is electrolysed in solution in molten cryolite, Na3AlF6. Cryolite is another aluminium ore, but is rare and expensive, and most is now made chemically.
Gold
It is now the most important and widely used process for extracting gold from ores.
The ore is first finely ground and concentrated by flotation.
To remove certain impurities, it may be roasted.
It is then mixed with a dilute solution of sodium cyanide (or potassium or calcium cyanide) while air is bubbled through it.
Soluble aurocyanide complex ion, Au(CN)-2^-1 is formed .
Silver, usually present as an impurity, also forms a similar soluble ion.
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