Question

The correct statement(s) related to the metal extraction processes is(are)

• A. A mixture of $PbS$ and $PbO$ undergoes self-reduction to produce $Pb$ and $S{O}_2$.
• B. In the extraction process of copper from copper pyrites, silica is added to produce copper silicate.
• C. Partial oxidation of sulphide ore of copper by roasting, followed by self-reduction produces blister copper.
• D. In cyanide process, zine powder is utilized to precipitate gold from $Na\left[Au(CN{)}_2\right]$.

Answer 1

Answer: (A), (C), (D)

(A) $PbS+2PbO\stackrel{\text{ self reduction }}{\to }3Pb+S{O}_2\uparrow$
So option (A) is correct.
(B) In the extraction $Cu$ from copper pyrite $CuFe{S}_2$
$Si{O}_2$ is added to remove $FeO$ as slag $FeSi{O}_3$.
So option (B) is wrong.
(C) $\underset{\text{ concentrated ore }}{CuFe{S}_2}\stackrel{\text{ roasting }}{\to }\underset{\text{(matte) }}{\underbrace{C{u}_{2}S+FeS}}+S{O}_2$
$FeS+O_2⟶FeO+S{O}_2$
$C{u}_{2}S+O_2⟶C{u}_{2}O+S{O}_2$
$C{u}_{2}S+2C{u}_{2}O⟶\underset{\text{ (Bister copper) }}{6Cu}+S{O}_2$
So, option (C) is correct.
(D) $Zn+2Na\left[Au(CN{)}_2\right]\to N{a}_2\left[Zn(CN{)}_4\right]+2Au\downarrow$
So, option (D) is correct.