click on the link below to download the PDF
Click here 📌
Define Metallurgy
The science and technology regarding the extraction of metals from ores and their purification for the use is called metallurgy.
Occurrence of metals
The compounds of metals that occur in nature along with the impurities are called minerals.
Most metals being reactive do not occur in nature in free state but are found in combined state as their salts such as oxides, carbonates, sulphides and nitrates.
However, the most unreactive metals that are not affected by air, water and other natural factors like silver, gold, platinum, generally occur in free state.
Basic principles of metallurgy
Pure metal is obtained from the ore by the following stages.
- Concentration of ores
- Extraction of metals
Separation based on gravitation
The heavy particles of ores can be easily separated from the light particles of gangue by the gravitational method.
Wilfley table method
Powdered ore obtained from lumps of the ore using ball mill is poured on the table and a stream of water is also released from the upper side.
The table is kept vibrating continuously.
As a result, the lighter gangue particles are carried away along with the flowing water, while the heavier particles in which proportion of minerals is more and proportion of gangue is less, are blocked by the wooden riffles and get collected on the slits between them.
Hydraulic separation method
Ground ore is released in the tank. A forceful jet of water is introduced in the tank from the lower side.
There is a tapering vessel similar to that used in a grinding mill. It opens in a tank-like container that is tapering on the lower side. The tank has an outlet for water on the upper side and a water inlet on the lower side.
At the same time the heavy particles of the ore are collected at the bottom from the lower side of the tank. In short, this method is based on the law of gravitation, wherein particles of the same size are separated by their weight with the help of water.