Question

Cassiterite is concentrated by:
a) Levigation
b) Electromagnetic separation
c) Floatation
d) Liquefaction

Answer 1

Hint: Cassiterite or tinstone - an ore of tin being non-magnetic can be separated from magnetic impurities like Fe and Mn from this method.

Complete step-by-step answer:
Now let us check the options one by one

a) Levigation: The process of removal of heavy ore particles from lighter gangue particles by washing with water is called levigation. The lighter gangue particles are washed away with a stream of water while the heavy ore particles settle down. This method is generally used for oxide ores of iron and tin.
b) Electromagnetic separation: It is a process in which valuable minerals that are attracted by a magnetic field are recovered from a mixture using a magnetic force.
This technique is used in metallurgy to remove unwanted particles like sand, clay rocks, etc. known as gangue particles from the ore. This method is applicable to those ores which in pure forms are attracted by the magnetic field but the impure forms (sand, clay, rocks, etc.) of the ore do not.
c) Floatation: This method is used for the purification of Sulphide ores and employs a mixture of water and pine oil which is made to froth in tanks to separate sulphide ores. The difference in wetting properties of ore and gangue particles separate them.
d) Liquefaction: Liquefaction refers to the process of converting into liquid. By applying high pressure and cooling, the gas can be changed into a liquid state i.e. liquefied.
As Cassiterite is an ore that is non-magnetic, hence it can be separated by electromagnetic separation.

The correct option is B.

Note: The possibility to make a mistake is that you may choose option A. But in levigation the heavy ores are separated from lighter ones. But Cassiterite is an ore that is non-magnetic so by electromagnetic separation we can separate from the impurities.