Question

Cassiterite is concentrated by:

Answer 1

Hint: Identify the metal whose ore is cassiterite. The impurities present with cassiterite can be attracted by an electromagnet. The metal to be extracted exists as an oxide in cassiterite. Cassiterite can be concentrated by removing impurities present along with it keeping in mind their magnetic properties.

Complete answer:
Cassiterite is a tin oxide mineral. It is usually opaque in nature, but at times it is translucent in thin crystals. It is a desirable gem due to lustre and multiple crystal faces. Cassiterite has been the chief form to obtain tin and is still the most important source of tin.
Cassiterite is a mineral ore containing about 57% w/w of Sn and remaining is impurities like quartz, monazite, rutile and zircon. The initial step involves removing impurities to concentrate the mineral oxide for further refining.
The impurities mentioned above have magnetic properties i.e. they are attracted by a strong electromagnet. On the other hand, tin oxide is diamagnetic and is not attracted by an electromagnet.
The ore extracted is first washed and passed through a high magnetic separator that will separate the impurities from the mineral oxide. Therefore, cassiterite is concentrated by electromagnetic separation.

So the correct answer is option (B).

Note:
Concentration of cassiterite ore is a special case of electromagnetic separation. This is because electromagnetic separation is used when the desired metal has magnetic properties and the impurities are not attracted by a magnet. For example, in haematite ore, iron oxide is attracted by the strong electromagnet and the impurity (silicon oxide) is separated out as it is diamagnetic.