metallurgy Flashcards
Bauxite
Principal Ore of aluminium
AlOx(OH)3-2x
0<x<1
Kaolinite
[Al2(OH)4Si2O5]
Ore of aluminium
form of clay
Haematite
Iron ore
Fe2O3
Magnetite
Iron ore
Fe3O4
Siderite
Iron ore
FeCO3
Iron pyrites
Iron ore
FeS2
Sphalerite
Zinc blende
ZnS
Calamine
Zinc ore
ZnCO3
Zincite
ZnO
Zinc ore
Copper pyrite
copper ore
CuFeS2
Malachite
copper ore
CuCO3.Cu(OH)2
Cuprite
copper ore
Cu2O
Copper glance
copper ore
Cu2S
Gemstones are impurities of which compound?
Al2O3
What is the impurity in ruby
Cr
What is the impurity in sapphire
Co
What is concentration of ore?
Removal of impurity
Also called dressing or benefaction
Hydraulic washing
Concentration of ore based on difference in densities of gangue and ore
Which type of ore is froth floatation method used for
Sulphide ores
Function of collectors in froth floatation method
Enhances non-wettability of mineral particles
Name collectors used in froth floatation method
pine oils, fatty acids, xanthates
Name froth stabilisers
Cresol, aniline
What do we do when there are two sulphides present in the same ore? Give example
Depressants to separate sulphides
E.g. NaCN, prevents ZnS from coming to froth but allows PbS
Impurities present in bauxite
SiO2, iron oxides, TiO2
do leaching rxn from pg 154 ncert part 1 class 12
Al2O3 + NaOH + H2O –> Na[Al(OH)4]
prod^ + CO2 –> Al2O3 . xH2O
dehydration of^
In extraction of gold, silver etc., what is used + what is added extra
NaCN, KCN
O2/air added extra
Formula of complex formed in extraction of gold silver with NaCN/KCN and subsequently what is the compound reacted with?
[M(CN)2]- (aq.)
reaction with Zn because it will form [Zn(CN)4]2-
Method of extraction of crude metal from concentrated ore
- conversion to oxide by calcination/roasting
- reduction of oxide to metal
Calcination
Just heating
pg 155 ncert class xii part 1
Roasting
Rxn in the presence of oxygen
ncert class xii part 1 pg 156
Ellingham diagram
- Graph below will reduce graph above
- Gibbs free energy on y axis, temperature on x axis
Extraction of iron takes place in what?
blast furnace
do rxns next to diagram pg 160
Pig iron
Iron obtained from blast furnace, containing 4% carbon and impurities like S, P, Si, Mn
Cast iron
Made by melting pig iron with scrap iron and coke using hot air blast
slightly less carbon content
Purest form of commercial iron
Wrought iron/malleable iron
Prepared from cast iron by oxidising impurities in reverberatory furnace lined with haematite
Fe2O3 + 3C –> 2Fe + 3CO
How are oxides obtained from sulphide ores of copper
By roasting/smelting
2Cu2S + 3O2 –> 2Cu2O + 2SO2
Cu2O + C –> 2Cu + CO
Copper extraction in which furnace + what happens
ore is heated in reverberatory furnace after mixing with silica
In the furnace iron oxide is converted to slag (iron silicate)
FeO + SiO2 –> FeSiO3
Copper is produced in the form of copper matte which contains Cu2S and Fe2S
What is done to copper matte
Charged into silica lined converter. Some silica is also added and hot aire blast is blown to convert remaining FeS, FeO, and Cu2S/Cu2O
Blister copper is obtained at the end of the process. Blistered due to SO2
rxns pg 162
what is Al2O3 mixed with
Na3AlF6 or CaF2 because they lower the melting point of the mixture and bring conductivity
Hall-Heroult process ( aluminium ) cathode anode and rxn
cathode: steel vessel with lining of carbon
anode: graphite
2Al2O3 + 3C –> 4Al + 3CO2
how is copper extracted from low grade ores and scraps
by hydrometallurgy
leached out using acid or bacteria
Solution containing Cu2+ is trated w scrap iron or H2
Cu2+ (aq) + H2 (g) –> Cu (s) + 2H+ (aq)
refining methods
- distillation
- liquation
- electrolysis
- zone refining
- vapour phase refining
- chromatographic methods
Liquation
Low melting metal like tin can be made to flow on a sloping surface
distillation
low B.P. metals like Zn Hg
electrolytic refining: impurities in anode mud
antimony, selenium, tellurium, silver, gold, and platinum
zone refining
because impurities are more soluble in the melt than in the solid state of the metal
semiconductor materials like germanium silicon boron gallium indium
mond process for refining nickel
vapour phase refining
nickel is heated in a stream of carbon monoxide forming a volatile complex Ni(CO)4
the complex is decomposed at higher temp to obtain pure metal
pg 165
van arkel method for refining zirconium or titanium
Zr + 2I2 –> ZrI 4
ZrI4 –> Zr + 2I2
metal used to galvanise iron
Zn
Brass is an alloy of?
Cu and Zn
German silver is an alloy of?
Cu, Zn, Ni