In general extraction of metals

1. Extraction of
metals

2. Difference between rock, mineral and ore.
A rock is made up of 2 or more minerals, whereas a mineral is composed of
the same substance throughout. Examples of minerals include quartz,
feldspar minerals, calcite, sulfur and the clay minerals such as kaolinite and
smectite.
Ore- A mineral occurring in sufficient quantity and containing enough metal
to permit its recovery and extraction at a profit.
Examples: Cinnabar (HgS), an ore of mercury.
Sphalerite (ZnS), an ore of zinc.

3. A few most unreactive metals occur in nature in free state. Most of
the metals occur in nature in oxidized form as their compounds.
The process of extracting pure metal from its ore is known as
metallurgy.

4. Steps involved…
I Crushing and grinding of the ore.
II. Concentration or beneficiation of the ore.
III. Preliminary treatment of the concentrated
ore.
IV. Reduction.
V. Purification or refining of crude metal.

5. I. CRUSHING AND GRINDING OF THE ORE
• Most of the ores are obtained from
the crust of the earth in the form of
huge lumps.
• These lumps have to be converted
into powdered form so that the
chemical changes which have to
take place at the later stages may
become convenient.
• The huge lumps are broken into
small pieces in the jaw
crushers They are further pulverised
in stamp mill or ball mill.

6. II. CONCENTRATION OR BENEFICATION OF THE ORE
The removal of unwanted materials such as sand, clay, etc., from the pulverised ore is called concentration, dressing or benefication of the ore.
1. Hydraulic Washing,
Levigation or Gravity
Separation Method
2. Froth Floatation
Process.
3. Magnetic Separation
of Impurities
4. Leaching

10. III. PRELIMINARY TREATMENT OF THE CONCENTRATED ORE
1.
Calcination
2. Roasting

11. IV.
REDUCTION
• 1. Smelting or Reduction with
Carbon.
• 2. Auto-reduction.
• 3. Electrolytic Reduction.
• 4. Displacement Method
(Hydrometallurgy).

12. V. REFINING OF
METALS
Distillation.
Liquation.
Electrolytic Refining- or Electro-refining.