Question

An ore after levigation is found to have basic impurities. which of the following can be used as flux during smelting?

• A. (a) ${\mathrm{H}}_2{\mathrm{SO}}_4$
• B. (b) ${\mathrm{CaCO}}_3$
• C. (c) ${\mathrm{SiO}}_2$
• D. (d) Both $\mathrm{CaO}\mathrm{and}{\mathrm{SiO}}_2$

Answer 1

The correct option is C

(c) ${\mathrm{SiO}}_2$

Levigation: It is a method of concentrating the ore based on differences in the gravity of ore and gangue.

Acidic oxide: Nonmetal oxides are acidic in nature.

Removal of basic impurity: Basic impurity can be treated with acidic flux.

Slag: the acidic flux combines with a basic impurity to form a slag.

Smelting: It is a process of extraction of metal from ore.

${\mathrm{H}}_2{\mathrm{SO}}_4$- It is an acid.

${\mathrm{CaCO}}_3$ - Calcium carbonate is a carbonate salt.

${\mathrm{SiO}}_2$ - Silicon dioxide is a nonmetal oxide and acidic in nature.

$\mathrm{CaO}$ - Calcium oxide is a metal oxide and basic in nature.

So Silicon dioxide is a nonmetal oxide and can combine with basic impurity/flux during the smelting process.