Question

An ore gives out ${\mathrm{CO}}_2$ on being treated with dilute Hydrochloric acid. Which process should be used to concentrate this ore?

• A. Calcination
• B. Roasting
• C. Froth floatation
• D. Sedimentation

Answer 1

The correct option is A

Calcination

Explanation for the correct option

Option A) Carbonate ore

The given ore produces ${\mathrm{CO}}_2$ in the presence of dilute acid, which means the given ore is a carbonate ore.

Calcination

The carbonate ores are separated or purified using the calcination process. It is the process in which metal ores are burnt in the absence of air. As a result, metals are concentrated and metal oxide is obtained. The reaction is,

$$\begin{gathered} {\mathrm{CaCO}}_3\left(\mathrm{s}\right)\stackrel{\mathrm{calcination}}{\to }\mathrm{CaO}\left(\mathrm{s}\right)+{\mathrm{CO}}_2\left(\mathrm{g}\right) \\ (\mathrm{Calcium}(\mathrm{Calcium}(\mathrm{Carbon} \\ \mathrm{carbonate})\mathrm{oxide})\mathrm{dioxide}) \end{gathered}$$

Explanation for incorrect options

Option B) Roasting is used for sulphide ores.

Option C) Froth floatation is also used for sulphide ore concentration.

Option D) Sedimentation is used to separate bigger water soluble impurities and is a common process for many ores.

So, option (A) is correct.