Extraction Processes and Impurity Removal for Cassiterite Ore

To determine the correct statements regarding the extraction of metal from the ore cassiterite, let us analyze the nature of the ore and the metallurgical steps involved:

1. Identification of the Ore:

   • Cassiterite (also known as tinstone) has the chemical composition $\text{SnO}_2$. It is a primary oxide ore used for the extraction of tin ($\text{Sn}$).

2. Removal of Impurities (Option D):

   • Cassiterite ore typically contains magnetic impurities of wolframite, which consists of iron and manganese tungstates ($\text{FeWO}_4 \cdot \text{MnWO}_4$).
   • Since $\text{SnO}_2$ is non-magnetic while iron impurities (wolframite) are magnetic, magnetic separation is used as a concentration method to remove the iron-containing impurities from the ore.

3. Reduction Process (Option A):

   • The concentrated oxide ore ($\text{SnO}_2$) is reduced to metallic tin by heating with carbon (anthracite or charcoal) in a reverberatory furnace at high temperatures ($\approx 1200\text{ }^\circ\text{C} - 1300\text{ }^\circ\text{C}$):
     $\text{SnO}_2 + 2\text{C} \xrightarrow{\Delta} \text{Sn} + 2\text{CO}\uparrow$
   • Therefore, the extraction process involves the carbon reduction of an oxide ore.

4. Evaluation of Other Options:

   • Option (B) is incorrect: Self-reduction is used for sulphide ores of metals like lead ($\text{PbS}$), copper ($\text{Cu}_2\text{S}$), and mercury ($\text{HgS}$). Cassiterite is an oxide ore.
   • Option (C) is incorrect: The primary impurity in cassiterite is wolframite (iron/manganese impurity), not copper.

Thus, the extraction of metal from cassiterite involves carbon reduction of an oxide ore and removal of iron impurity.

Correct Options: (A) and (D)