Extraction of Metals - Result Question 3
####3. The correct statement is
(2019 Main, 10 April II)
(a) zone refining process is used for the refining of titanium.
(b) zincite is a carbonate ore
(c) sodium cyanide cannot be used in the metallurgy of silver.
(d) aniline is a froth stabiliser.
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Solution:
- The explanation of given statements are as follows:
(a) Zone refining process is used for the refining of B, Ga, In, $Si$ and $Ge$.
Ti is refined by van Arkel method.
Thus, statement (a) is incorrect.
(b) Zincite $(ZnO)$ is an oxide ore of $Zn$. Thus, statement (b) is incorrect.
(c) $NaCN$ is used in the hydrometallurgy of silver. It is known as Mc. Arthur Forrest process.
The reactions occuring during the process are as follows:
$$ Ag _2 S+4 NaCN \longrightarrow 2 Na\left[Ag(CN) _2\right]+Na _2 S $$
$$ \begin{array}{r} 4 Na _2 S+2 H _2 O+5 O _2 \longrightarrow 2 Na _2 SO _4+4 NaOH+2 S \ 2 Na\left[Ag(CN) _2\right]+Zn \longrightarrow Na _2\left[Zn(CN) _4\right]+2 Ag \end{array} $$
Thus, statement (c) is incorrect.
(d) Aniline and cresol help in stabilising the froth in froth floatation process.
Thus, statement (d) is correct.
