Metals

Metals:

• Metals are elements having high tensile strength.
• High tensile strength means that they can be stretched without breaking.
• Metals are ductile.
• Ductility means that metals can be drawn into thin wires.
• Metals are malleable.
• Malleability means that metals can be beaten into thin sheets.
• Metals are good conductors of heat & electricity.
• They also have a property called sonorous. Sonorous means they produce a sound when hit hard.

Reactions of metals:

1. Reaction with oxygen: All metals react with oxygen to form metal oxides. For example: Copper reacts with oxygen to form copper oxide.
2. Reaction with water: All metals do not react equally well to form metal hydroxides & hydrogen gas. For example: Sodium reacts vigorously & generally bursts into flames.
3. Reaction with acids: Most of the metals react chemically to form salt & hydrogen gas.

Non-Metals:

• Non-metals do not have properties like high tensile strength or ductility.
• Examples: Hydrogen, Nitrogen, Bromine, Phosphorus.

Metalloids:

• The border line elements which can show some properties of metals and non-metals are called metalloids.
• Examples: B, Si, Ge, As, Sb, Te, Po, At.

Minerals and Ores:

• Minerals: The naturally occurring earthy chemical substance containing metal in any proportion on the earth’s crust is called minerals.
• Examples: Bauxite (Al₂O₃·2H₂O), Clay (Al₂O₃·2SiO₂·2H₂O).
• Ores: The naturally occurring minerals from which metal can be extracted profitably & conveniently are called ores. Thus, all ores are minerals but not all minerals are ores.
• Examples: Bauxite (Al₂O₃·2H₂O).

• Ag: Upper pyritic (CuFeS₂)
• Au: MacArthur Forrest (Cyanide)
• Fe: Hematite (Fe₂O₃)
• Ni: Garnierite [(Ni,Mg)₆Si₄O₁₀(OH)₈]
• Zn: Zinc Blende (ZnS)
• Pb: Galena (PbS)
• Al: Bauxite [Al(OH)₃]
• Sn: Tin Stone (Cassiterite SnO₂)
• Hg: Cinnabar (HgS)

Different processes involved in Metallurgical process:

• The extraction of metal from its ore & refining the metal is called metallurgy.
• Metallurgy involves 3 major steps:
1. Concentration or dressing of the ore
2. Extraction of crude metal from concentrated ore
3. Refining

Pyrometallurgy:

• It is a method of extraction of metal from its ore by chemical reduction at high temperatures.

It is used in the extraction of Al, FeCl₃.

Ferric Chloride:

• It is a byproduct of extraction of metals from its ore by means of pyrites.
• It is used in water purification & also in the production works and extracted by this method.

Hydrometallurgy:

• It is a method for extraction of metal from its ore by dissolving that ore in some solvent to give soluble complex which can be further processed to get pure metal.

[ \text{Al}_2\text{O}_3 + 6\text{HCl} \rightarrow 2\text{AlCl}_3 + 3\text{H}_2\text{O} ] [ \text{FeS}_2 + \text{O}_2 \rightarrow \text{FeSO}_4 ]

Al can be extracted from AlCl₃ (when general) by [ \text{ABS} + \text{TQP}: 4\text{NaOH} \rightarrow 2\text{Na[Al(OH)}_4] + \text{Na}_2\text{S} ] or [ \text{Na[Al(OH)}_4] + \text{CO}_2 \rightarrow \text{Al(OH)}_3↓+ \text{NaHCO}_3 ]

Alloys & their use:

• Homogeneous mixture material with other elements called alloys are used which improves quality over single metal.
• Examples: Duralumin (Cu, Mn), Magnalium (Mg), Birmabright (Ni), Sillumin (Si). These are lightweight alloys used for aircraft parts manufacturing like wings, fuselage, etc., automobile machine parts & culverts/toys, etc.

Process involved in the extraction of Metals:

1. Crushing and Powdering:
• The ore is crushed and powdered.
2. Concentration of Ore:
• Hand picking
• Gravity Separation
• Froth Flotation
• Magnetic Separation
• Leaching
3. Calcination or Roasting of Ore:
• Calcination
• Roasting
4. Extraction of Metal:
• Carbon reduction (Smelting)
• Alumino thermite reduction
• Self reduction
• Electrolytic reduction
5. Purification or Refining of Metal:
• Liquation
• Poling
• Electrolytic refining
• Distillation
• Zone refining

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