In the cyanide process for extraction of gold | vedclass

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(B) Silver and gold are extracted by the cyanide process (Mac Arthur - Forrest process). After the preliminary crushing and concentration by froth flo

Vedclass · Accepted Answer

leaching agent to bring gold and silver into solution as cyanide complexes and thus separate these metal from impurities

Vedclass · Answer

(B) Silver and gold are extracted by the cyanide process (Mac Arthur - Forrest process). After the preliminary crushing and concentration by froth floatation process,the ore (crushed auriferous rocks in the case of gold) is leached with a dilute $(0.4 - 7\, \%)$ solution of sodium cyanide made alkaline by adding lime and kept agitated by a current of air. Silver (or gold) passes into the solution as argentocyanide (or aurocyanide). It is based on the fact that gold/silver dissolves in a dilute solution of sodium cyanide in the presence of atmospheric oxygen with the formation of a complex cyanide. Reaction: $4Au + 8NaCN + 2H_2O + O_2 \rightarrow 4Na[Au(CN)_2] + 4NaOH$ $Ag_2S + 4NaCN \rightarrow 2Na[Ag(CN)_2] + Na_2S$ Silver is obtained by reaction with $Zn$: $2Na[Ag(CN)_2] + Zn \rightarrow Na_2[Zn(CN)_4] + 2Ag$

$I$	$II$
$X$. Magnetic separation	$a$. $Ag_2S$
$Y$. Froth floatation	$b$. $FeCr_2O_4$
$Z$. Gravity separation	$c$. $Al_2(SiO_3)_3$

In the cyanide process for extraction of gold and silver from ores,the cyanide solution acts as a

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Match the method of concentration of the ore in column $I$ with the ore in column $II$ and select the correct alternate :

$I$ $II$

$X$. Magnetic separation $a$. $Ag_2S$

$Y$. Froth floatation $b$. $FeCr_2O_4$

$Z$. Gravity separation $c$. $Al_2(SiO_3)_3$

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