- Gravitational separation separates heavy ore particles from lighter gangue using water, based on difference in density (e.g., Wilfley table, hydraulic method).
- Magnetic separation uses an electromagnet to separate magnetic and non‑magnetic components of an ore (e.g., cassiterite).
- The froth flotation method is used for sulphide ores, where ore particles float on the froth due to their hydrophobic nature, while the gangue sinks.
- Vegetable oils (pine oil and eucalyptus oil) and air bubbles help form a froth that carries sulphide ore particles to the surface.
- Leaching involves dissolving the ore in a chemical solution (e.g., bauxite in NaOH), leaving gangue undissolved for separation.
Definitions [3]
Definition: Minerals
The elements or compounds, which occur naturally in the earth’s crust, are known as minerals.
OR
Minerals are the naturally occuring compounds of metals which are generally mixed with other substances such as soil, mud, sand, silica (Si02) limestone, rocks, etc. These earthly impurities are called gangue or matrix.
Definition: Ores
At some places, minerals contain a very high percentage of a particular metal, and the metal can be profitably extracted from it. These minerals are called ores.
OR
Ores are those minerals from which metals are extracted commercially at a comparatively lower cost and with minimum effort.
Definition: Concentration of ores
The process of separating gangue from the ores is called concentration of ores.
Key Points
Key Points: Occurrence of Metals
- Metals occur in either the free or combined state, depending on their reactivity.
- Metals are grouped as low, medium, or highly reactive, and each group has a different extraction method.
- Ores have impurities called gangue, which are removed before extraction.
- Low-reactive metals are extracted by heating alone; medium-reactive metals require roasting or calcination, followed by reduction.
- Highly reactive metals (such as Na, Mg, and Al) are extracted by electrolysis.
- Metals are purified by electrolytic refining, where pure metal deposits at the cathode and impurities form anode mud.
Key Points: Concentration of Ores
