Which of the following impurities are typically removed from Cassiterite ore via "Balling" or leaching with water after roasting?

Question

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Question Explanation:

Roasting Cassiterite ore converts sulfide impurities like CuS and FeS into water-soluble sulfates, $C u S O_{4}$ and $F e S O_{4}$ . These sulfates are then removed by "Balling" or leaching with water. Arsenic impurities ( $A s_{2} O_{3}$ ) are volatile and escape as gas, while silica ( $S i O_{2}$ ) is insoluble and removed as slag.

Concept:

Metallurgy, Roasting, Leaching, Purification of Tin.

Solution:

During the roasting of Cassiterite ( $S n O_{2}$ ) ore, sulfide impurities such as chalcopyrite ( $C u F e S_{2}$ ) are oxidized.

$2 C u F e S_{2} (s) + 5 O_{2} (g) Δ C u S O_{4} (s) + F e S O_{4} (s) + S n O_{2} (s)$

The resulting copper(II) sulfate ( $C u S O_{4}$ ) and iron(II) sulfate ( $F e S O_{4}$ ) are water-soluble. Subsequent leaching with water dissolves these sulfates, separating them from the insoluble tin(IV) oxide ( $S n O_{2}$ ).

$C u S O_{4} (s) + H_{2} O (l) \to C u^{2 +} (a q) + S O_{4}^{2 -} (a q)$

$F e S O_{4} (s) + H_{2} O (l) \to F e^{2 +} (a q) + S O_{4}^{2 -} (a q)$

Arsenic impurities, if present, are typically removed as volatile $A s_{2} O_{3}$ during roasting. Silica ( $S i O_{2}$ ) remains insoluble and is removed in later stages, often as slag. Therefore, $C u S O_{4}$ and $F e S O_{4}$ are the impurities removed by leaching with water after roasting.

Final Answer: A and B

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