Metallurgy

Metallurgy

The process of extracting metal in pure form from its ore is known as metallurgy.

Minerals:

The compound of a metal found in nature is called a mineral. A mineral may be a single compound or a complex mixture.

Ores:

Those minerals from which metal can be economically and easily extracted are called ores.

All ores are mineral but all minerals are not ores.

Gangue (or matrix):

The ore is generally associated with earthy impurities like sand, rocks and limestone known as gangue or matrix.

Flux:

A substance added to ore to remove impurities is called flux. There are two types of flux –
(i) acidic flux (ii) basic flux

Acidic flux is added to remove basis impurity

SiO₂          +     FeO          →       FeSiO₃

acidic flux       basic impurity      Ferrous silicate

Basic flux is added to remove acidic impurity.

CaCO₃      +    SiO₂          →       CeSiO₃   +   CO₂

basic flux         acidic impurity    Calcium silicate

Slag:

Combination of gangue with flux in ores forms a fusible material which is called slag.

Gangue    +     CaO          →       slag

SiO₂          +     CaO          →       CaSiO₃

Concentration:

The process of removal of gangue from the ore is known as concentration of ore. Concentration of ore can be carried out in the following ways depending upon the nature of th eore.

(i) Gravity separation      (ii) Magnetic concentration

(iii) Froth flotation process     (iv) Chemical methods

Calcination:

The Calcination is a process in which ore is heated, generally in the absence of air, to expel water from hydrated oxide or carbon dioxide from a carbonate at temperature below their melting point example:

Al₂O₃ . 2H₂O  →∆     Al₂O₃ + 2H₂O

CaCO₃      →∆    CaO + CO₂

Roasting:

Roasting is a process in which ore is heated usually in the presence of air, at temperatures below its melting points.

ZnS + 2O₂  →  ZnSO₄;
CuS + 2O₂  →  CuSO₄

Smelting:

The reduction of oxide ore with carbon at high temperature is known as smelting.

Fe₂O₃ + 3c  →  2Fe + 3CO;

PbO + C  →  Pb + CO

Important metals and their ores

Alloys:

An Alloy is a metallic intimately mixed solid mixture of two or more different elements, at least one of which is metal.

Alloys are homogeneous in molten state but they may be homogeneous or heterogeneous in solid state.

Important alloys & their uses

Amalgam:

An alloy, in which one of the component metals is mercury, is called amalgam. In alloy, the chemical properties of component elements are retained but certain physical properties are improved.

Compounds of metal and non-metal and their uses:

1. Ferrous oxide (FeO): In green glass, Ferrous salt.
2. Ferric oxide (Fe₃O₄): In electroplating of ornaments and formation of ferric slat
3. Ferrous sulphate (FeSO₄ . 7H₂O): In dye industry, and Mohr's salt
4. Ferrous hydroxide [(Fe(OH)₃)]: In laboratory reagent and in making medicines.
5. Iodine (I2): (i) As antiseptic, (ii) In making tincture of iodine.
6. Bromine (Br₂): (i) In dye industry, (ii) As laboratory reagent
7. Chlorine (Cl₂): In the formation of (i) Mustard gas (ii) Bleaching powder
8. Hydrochloric acid (HCl): In the formation of aquaregia (3HCl : 1HNO₃) and dyes
9. Sulphuric acid (H₂SO₄): (i) As a reagent (ii) In purification of petroleum (iii) In lead storage battery.
10. Suphur dioxide (SO₂): (i) As oxidants & reductants (ii) As bleaching agent
11. Hydrogen Sulphides (H₂S): In qualitative analysis of basic radical (group separation)
12. Sulphur (S): Antiseptics, vulcanization of rubber, gun powder, medicine.
13. Ammonia (NH₃): As reagent in ice factory.
14. Phosphorous: (i) Red (P₄) refrigerant, in match industry etc. (ii) White (P₄) – Rat killing medicine.
15. Producer gas (CO + N₂): (i) In heating furnace (ii) Cheap fuel (iii) In Extraction of metal
16. Water gas (CO + H₂): (i) As fuel (ii) Welding work
17. Coal gas: (i) As fuel (ii) Inert atmosphere
18. Nitrous oxide (N₂O): Laughing gas, Surgery.
19. Carbondioxide: (CO₂): Sodawater, Fire extinguisher.
20. Carbon monoxide (CO): In phosgene gas (COCl₂).
21. Graphite: As electrodes:
22. Diamond: Ornaments, Glass cutting, Rock drilling.
23. Alum [K₂SO₄Al₂ (SO₄)₃ . 24 H₂O]: (i) Purification of water (ii) Leather industry.
24. Aluminium sulphate [Al₂(SO₄)₃ . 18H₂O]: In paper industry/fire extinguisher.
25.  Anhydrous aluminium chloride (AlCl₃): Cracking of petroleum.
26. Mercuric Chloride (HgCl₂): Calomel, Insecticides (Corrosive sublimate)
27. Mercury oxide (HgO): Oientment, poison.
28. Mercury (Hg): Thermometer vermillion, amalgam.
29. Zinc Sulphide (ZnS): White pigment.
30. Zinc Sulphate (White vitriol) (ZnSO₄ . 7H₂O): Lithopone, Eye ointment.
31. Zinc Chloride (ZnCl₂): Textile industry.
32. Zinc oxide (ZnO): Ointment.
33. Zinc (Zn): In battery.
34. Calcium carbide (CaC₂): Calcium cyanide & acetylene gas.
35. Bleaching powder [Ca(OCl)Cl]: Insecticides, Bleaching actions.
36. Plaster of paris [(CaSO₄)₂ . 2H₂O / CaSO₄ ½ H₂O)]: Statue, Surgery.
37. Calcium sulphate (CaSO₄ . 2H₂O): Cement industry.
38. Calcium carbonate (CaCO₃): Lime & toothpaste.
39. Copper sulphate (CuSO₄ . 5H₂O): Insecticides, Electric cells.
40. Cupric oxide (CuO): Blue & green glass, purification of petroleum
41. Cuprous Oxide (Cu₂O): Red glass, pesticides.
42. Copper (Cu): Electrical wire.
43. Sodium nitrate (NaNO₃): Fertilizer.
44. Sodium Sulphate (Glauber salt) (Na₂SO₄ . 10H₂O): Medicine, cheap glass.
45. Sodium bicarbonate (Baking soda) (NaHCO₃): Fire extinguisher, bakery, reagent.
46. Sodium Carbonate (Washing soda): (i) Glass industry (ii) Paper industry (iii) Removal of permanent hardness of water (iv) washing
47. Hydrogen peroxide (H₂O₂) Oxidants & reductants, Insectidides.
48. Heavy water (D₂O): Nuclear reactor.
49. Liquid hydrogen: Rocket fuel.