Transcript 26. Metallurgy

Chemistry
Metallurgy - 1
Session opener
What is lye?
KOH-Aqueous
Session objectives
1.
To know about origin and distribution of elements
2.
Different modes of occurrence of metals
3.
Minerals of India
4.
Metallurgy
5.
Different methods of concentration of ores
6.
Different methods to convert concentrated ore into
oxides
7.
Methods to convert oxide ore into metal –
Smelting, Aluminothermy, Hydrometallurgy,
Electrolytic reduction.
Origin Of Element
Universe 89%H
and 11% He
Formation of stars
(made of clouds of
H and He)
Nuclear fusion reaction
started in formation of elements
upto iron (atomic number 26)
Rise in temperature of
stars due to gravity
Origin Of Element
By nuclear process
98
42 Mo
+ 0n1
99
42Mo + r
90
43 Tc
Formation of
other elements
+ neutrino
By cosmic radiations
14
1
7 N +0
n
14
1
6 C +1 H
+ –
The Zones in Earth’s Interior
Give circles different colours
Mantle
(Fe and Mg silicates)
Crust(rocks)
Outer core (liquid Fe–Ni only)
Inner core
solid (Fe–Ni)
Modes of Occurrence of Elements
Native state
Insert pic
Combined state
Ask yourself
Name the element which is extracted from sea water.?
Magnesium
Name the element which is extracted from sea weeds.?
Iodine
Terms Used in Metallurgy
Ore
Ganuge or matrix
mineral
Ask yourself
Clay Al2O3.2SiO2.2H2O and
bauxite Al2O3.2H2O
are two sources of Al.
Are they ores or minerals?
Al can be obtained profitably only from bauxite.
 Its ore and clay is mineral
Flux
Flux + gangue
e.g.
CaO + SiO2
Acidic Flux
•
Removes basic impulses
 eg  P2 O5 , SiO2
Basic Flux
• Removes acidic impurities
 eg  CaO , MgO
Slag
(fusible
mass)
CaSiO3
(slag)
Refractory materials
Furnaces
A place where
metallurgical
processes
take place
Lining of heat
resistant bricks
Cup and cone
arrangement
for finding
Slag hole
Hole for molten metal
Hot air blast
Reverberatory furnace
Open Health Furnace
Slag
steel
Air Producer
gases
Hot gases
Bessemer converter
Magnesia lining
Sand+air
Ask yourself
Can you name lustrous non-metals?
Iodine and graphite
Flow sheet for
general metallurgical
operations
Ore
Concentration of ore
Conversion of ore into oxides
Conversion of ore into free metals
Purification of metal
Concentration of ore
1. Hand picking : to show by picture
2. Levigation or Hydraulic washing or gravity separation.
Jet of air
Vibration table
with grooves
Denser ore
particles
Water
Gangue
particles
Concentration of ore
3. Magnetic Concentration
animation
Belt
B
A
Magnetic roller
Wolfarite FeWO4 and Cassiterite SnO2
Concentration of ore
4. Froth Flotation Process
Froth
Ore + pine oil
Concentration of ore
5. Leaching
Leaching of bauxite
Al2O3 2H2O+2NaOH
2NaAlO2
Bauxite ore
Sodium
aluminate
Al(OH)3 + NaOH
NaAlO2+2H2O
Aluminum
hydroxide
Heat
Al(OH)3 
+
Al2O3 +
3H2O
3H2O
Concentration
Leaching of Argentite
Ag2S + 4NaCN
2Na[Ag(CN)2] + Zn
4Au + 8KCN+ 2H2O + O2
2K[Au(CN)2] + Zn
2Na[Ag(CN)2] +
Na2S
Na2 [Zn(CN)4] + 2Ag
4K[Au(CN)2] + 4KOH
K2 [Au(CN)4] + 2Au
Electrostatic concentration
Principle
The good conductors of electricity
become electrically charged under the
influence of an electrostatic field and
therefore they are repelled by
electrode carrying the like charge.
Example
Lead sulphide (good conductor) is
separated from zinc sulphide (poor
conductor) by this method.
Oxidation of ore or conversion
of ore into oxide
Concentrated ore
Calcination
or Roasting
Oxide of ore
Calcinations
•Ore is heated in absence of air.
•Carbonate ores are converted to oxide

CaCO3 .MgCO3 
 CaO  MgO  CO2
Dolomite

Al2O3 .2H2 O 
 Al2O3  2H2O
Ask yourself
Name calcination originated from ore
calcite which on thermal decomposition
gives quick lime.
Oxidation of ore or
conversion of ore into
oxide
Roasting
Ore is heated in presence of air.
Sulphide ores converted into oxide.
4FeS2  11O2 
 2Fe2O3  8SO2
Reduction of oxide to
free metal
1. Smelting( Reduction by carbon)
Oxide Ore + C + flux  Metal
Fe2O3  3C  2Fe  3CO
CaCO3  CaO  CO2
CaO SiO2  CaSiO3
Flux
Gangue
Slag
Reduction of oxide to free metal
2. Auto Reduction or Self Reduction


air
air
CuS  CuO  CuS  Cu  SO2
2PbS  2O2  2PbO  2SO2
2PbO  PbS  3Pb  SO2
Reduction of oxide to free metal
3. Goldschmidt alumino thermite Process
Thermite = 3 parts Fe2O3 + 1 part Al
Cr2O3
+ 2Al
3Mn3O4 + 8Al
3MnO2
+ 4Al
Fe2O3
+ 2Al




2Cr + Al2O3
9Mn + 4Al2O3
3Mn + 4Al2O3
2Fe +
Al2O3
Do you know
Silver paint contains Al
Gold paint contains Cu
Reduction of oxide to free
metal
4. Amalgamation Method
distill
Nativeore  Hg  Amalgam 
 Pure metal  Hg
5. Hydrometallurgy
more reactive metal displaces the less reactive
metal from its salts.
2Na  Ag(CN)2   Zn Na2 Zn(CN)4   2Ag
Electrolytic reduction
(electrometallurgy)
NaCl 
 Na  Cl
electricity
(fused)
At Cathode
Na  e  Na
(Made of iron)
At Anode
(Made of graphite)
2Cl  2e  Cl2 (g)
Do you know
Alkali and alkaline earth metals are obtained
by electrolysis of their chlorides, oxides and
hydroxides.