12th Class Principles of Extraction of Elements Full Chapter Notes

12th Class Principles of Extraction of Elements Full Chapter Notes CBSE 12 Class Principles of Extraction of Elements Full Chapter Notes

12th Class Principles of Extraction of Elements Full Chapter Notes CBSE 12 Class Principles and Processes of Extraction of Elements Full Chapter Notes

 

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Method of Metallization

(1) Pulverization (Gravity Separation Method) – In this method by grinding a given ore into a vessel filled with water and stirring it, the dust particles float on the surface while the heavy particles of the ore float on the bottom. Now take out this ore and put it on a sloping garden, make a strong stream of water flow and put a mesh from the front side, from which the dust particles come out. and the ore remains

(2) Concentration :- Two methods are used for this

(a) – Magnetic separation method (b) Foam flotation method

(A) – Magnetic separation method –

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This method is not for sulphide ore, in which any other ore is dropped on the carrier plates on the magnet roller, due to which it moves while moving forward. Whereas the materials which do not show the properties of magnets keep falling straight

(B) Foam flotation method – This method is applicable only for sulphide ores

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Taking water in a vessel, mix the powdered sulphide ore in it, then mix various substances in it and flow it in the air, due to which the ore floats in the form of froth, which settles and settles on the bottom due to being heavy due to gangue. Various substances are used in this method,

the details of which are as follows.
(1) Foaming agent – Turpentine or pine (Eucalyptus oil) is used as a foaming agent

(2) Flotation agent – For this, sodium alkyl (ethyl) xanthate is added, it repels water in sulfide particles, due to which the particles float on water, it is also called collector

(3) Foam factor – for this add cresol or aniline

(4) Active factor – for this who add CuSo4 which increases the salting capacity

(5) Depressant factor – sodium cyanide or Na2Co3 is added to reduce the foam formed in it

Q – (1) Explain how ZnS and PbS are separated?

Ans – Zn blades use NaCN as a depressant to separate Zns and Galena (PbS). This NaCN prevents ZnS from coming into the foam in the froth flotation method while it does not prevent PbS, thus separating the two Goes

 

 

12Th Class Principles Of Extraction Of Elements Full Chapter Notes
12Th Class Principles Of Extraction Of Elements Full Chapter Notes

 

General principles of extraction of metals pdf general principles of extraction of metals pdf principles of metallurgy pdf general principles and processes of isolation of elements ppt metallurgy class 12 ncert notes pdf

12th Class Principles of Extraction of Elements Full Chapter Notes CBSE 12 Class Principles and Processes of Extraction of Elements Full Chapter Notes

 

Obtaining alumina from bauxite ore – Bauxite has the general formula Al2O3.2H2o. Impurities of Fe2O3, SiO2, Tio2 are found in it, on the basis of these impurities, the method of obtaining alumina from bauxite is selected.

(1) Bayer method – When the impurities of Fe2O3 and temporary O2 are present in almost equal quantity in bauxite ore, then this method is used, NaoH is added to the given ore.

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(2) Hall method – When the impurities of Fe2O3 are added to the bauxite ore, this method is used, in which the given ore is treated with Na2Co3.

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(3) Sarpet method – When the impurities of SiO2 are added to the bauxite, then this method is used, in which the given ore is treated with C + N2

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Dissolution and Displacement 

(A) Fragmentation : – This process is done in a refractory furnace, in which a sulphide ore is heated in excess of air, due to which So2 gas is liberated and oxide of the metal is obtained in the form of fractured ore.

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=> Copper fracture

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(B) Settlement : – This is also done in the reflecting furnace, in which an ore is heated in the absence of air, sulphide ore is not taken in the settlement.

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Q (2) Write the difference between fracture and displacement?

Bhajan – It is done in excess of air
chemical change takes place in

Installation – It is done in the absence of air
does not undergo chemical change

 

Principles of Extraction of Elements metallurgy class 12 ncert notes pdf principles of metallurgy pdf general principles and processes of isolation of elements meaning in hindi general principles of metal extraction slideshare general principles and processes of isolation of elements ppt

 

Imp*
smelting ( reduction by carbon or coke ) – smelting of smelted ore is done in blast furnace-> By heating the melted ore with carbon (coke) at high temperature, it gets reduced to metal, this is called smelting.

-> Vatya kiln is made of iron, its height is about 30 m and diameter is 6 to 8 m, in which there is a thousand of bricks.

-> Different reactions take place in this furnace at different temperature levels, which are called its different zones.

-> Reduction zone – 673k to 973k
Central Zone (Territory Zone) – 1173k to 1473k
Consolidated area – 1373k to 1573k
Combustion zone – 1773k to 2173k

-> In this furnace there are two sides of air towyers
-> Equations occurring in the blast furnace – In the blast furnace 8 parts of the fired ore (oxide ore) and 4 parts of carbon (coke) and CaCo3 are taken one part

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-> In this process impure iron (pig iron) is obtained
-> It contains about 4% carbon besides P,S,Si,Mn,etc. impurities are also found

=> Cast Iron :-
Hot molten cast iron is poured into a mold made of sand and cooled
On cooling this iron rapidly, the impurities of C are present in the form of cementite Fe3C, it is called white cast iron.
If it is cooled slowly, the carbon remains in the form of graphite which is called brown cast iron.

Note – If the carbon impurities remain up to 3% in cast iron, then it remains very hard and brittle and does not rust.

=> Braided iron : – If iron is pure form, the impurities of carbon in it are about 0.2 percent to 0.5 percent.
Due to impurities in dharamvir iron, it melts at about 1473k to 1573k whereas wrought iron melts at 1823k

Making wrought iron from cast iron –

-> Oxidizes the cast iron with hematite by hot air in the reflection furnace, thereby separating the carbon impurities as carbon monoxide while other impurities evaporate
-> It forms metal slurry CaSio3 from limestone CaCo3 mixed as slaked, from which it is beaten by roller with a steam driven hammer, which brings out the metal sludge and obtains molten iron

-:- Steel :- The amount of carbon in this is about 0.15 to 1.5%, which is between cast iron and wrought iron, that is, steel is purer than cast iron.

 

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Obtaining aluminum metal from alumina ( Hall Heralt method )

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In this, a steel iron vessel is taken from which a carbon lining is attached, it acts as a cathode, in this cell (vessel) there is a rod of graphite which acts as anode, in this paper cryolite Na2AlF6 with Al2o3 and By mixing fluoride (CaF2), bulbs are placed in parallel to these

Note – When the amount of alumina in the cell decreases, the bulb starts burning due to increase in resistance.
The melting point of aluminum is 2323k, so by adding Na2AlF6 and CaF2 it reduces to about 1173k.

cell equation

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=> According to the second hypothesis, cryolite dissociates first on passing an electric current.

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-:- Removal of gold ores on silver

(A) Removal of silver
Ore Silver Glass Argentite(Ag2S) Horn Silver (Agcl)

Mixing NaCN or KCN in the above ores of silver is done, due to which silver complex is obtained, then Zn zinc is added to this complex, then Zn complex will be obtained and silver metal gets deposited.

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(B) Extraction of gold – For this, by adding NaCN to pure gold, it is oxidized by hydrolysis, then gold complex is obtained, then if this complex is treated with Zn, then zinc complex is obtained and gold( Au) will be deposited

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-:- Basemarization :-

-> The ore obtained after smelting is reduced by putting it in the Besmer converter furnace.
-> It is a pear shaped steel furnace
-> Inside it is a weapon of acidic sio2 or alkaline mgo, which acts as a slurry.
-> There is a tube on one side of this furnace, through which the air is sent inside, this tube is called Sundika.

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-::- Ellingham diagram for the selection of reductants –
When one mole of oxygen is reacted with different elements, then different types of oxides of those elements are obtained.
At positive and negative values ​​of G°, this curve is affected (changes)

=> Conclusion of Ellingham Diagram

-> Since the value of G° is negative, the reaction will proceed in the forward direction.
-> The value of G° in the formation of metal oxides depends on the temperature
-> If two or more reactions are happening simultaneously in a system and their resultant G° is also negative, then all these reactions will take place in the forward direction.

-:- Discussion of Alingham’s approach in thermal reduction of ore

(1) From this diagram a reducing agent is chosen for the reduction of a metal oxide to a metal.

(2) If the phase change of elements is going solid -> liquid -> gas then the value of their entropy change s will increase to positive

(3) But if the state change of elements is gas -> liquid -> solid then the entropy change will decrease to negative

(4) If the phase change is not happening, then the diagram will be obtained in a straight line.

(5) If the value of G° is negative in the Ellingham diagram, then it will be permanent (oxide of metal) Similarly, if the value of G° is positive, then that metal oxide will be temporary and will start decomposing automatically.

(6) If the curves of any two metal oxides intersect, then the value of G° at that intersection will be zero.

(7) When the metal obtained at a reduction temperature is in the liquid state, the reduction of that solid occurs easily.

-:- Limitations of Ellingham Diagram
(1) This diagram shows the reduction of a metal oxide but does not show the kinetics of the reduction i.e. the rate of reaction

(2) This diagram is not always true when reactants and products are in solid state in a reaction.

=> Because for solids the value of the equilibrium constant K i.e. the active concentration of K is taken as a unit

 

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