Question

Cassiterite ore consists of magnetic impurity named as :
A. chromite
B. wolframite
C. magnetite
D. Limonite

Answer 1

Hint: Common name of cassiterite is tin stone because it is an ore of tin which is called as tin oxide having the chemical formula $Sn{{O}_{2}}$. The magnetic impurities that are present in cassiterite is the combination of tungstates of iron and manganese and this impurity can be separated from non magnetic properties through electromagnetic separation.

Complete step by step solution:
Cassiterite which is commonly called as tin stone is a tin oxide $Sn{{O}_{2}}$ mineral. Usually the nature of tin stone is opaque but in thin crystals sometimes it is translucent also. It has multiple crystal faces and is categorized as a desirable gem due to its luster. Cassiterite is always the best and chief way to obtain tin and is a very important source of tin. Cassiterite as a mineral ore contain about 57 % w/w Sn and the remaining part is of impurities. The impurities have magnetic properties in them that means they get attracted by a strong electromagnet. And the cassiterite which is made up of tin oxide is not attracted by any electromagnet and is diamagnetic in nature. The magnetic impurities that are present in cassiterite is the combination of tungstates of iron and manganese and this combination is known as wolframite $(FeW{{O}_{4}}+MnW{{O}_{4}})$ and they are paramagnetic in nature. Wolframite can be separated from non magnetic properties through electromagnetic separation. In electromagnetic separation the powdered ore is dropped over the conveyor belt which is moving around the two rollers and among the two rollers one has electromagnet in it. And the magnetic impurities get attracted by the magnetic roller and the ore particle falls in separate heap

Thus the correct option will be (B).

Note: The process of magnetic separation is also used in grain, dairy, oils and textiles. Being the ore of iron and having magnetic properties with them, magnetite and ilmenite can also be separated through this process. Cassiterite also have impurities like monazite, rutile quartz and zircon and they all have magnetic properties in them.