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  • What happens when (a) Silver is leached with in the presence of air? (b) Copper matte is charged into silica lined converter and hot air blast is blown?

What happens when

(a) Silver is leached with NaCN in the presence of air?

(b) Copper matte is charged into silica lined converter and hot air blast is blown?

(c) NaCN is added in an ore containing PbS and ZnS during concentration by froth floatation method?

 

 

 

 
 
 
 
 

Answers (1)

(a) 4Ag+8NaCH+2H_{2}O+O_{2}\rightarrow 4Na\left [ Ag(CN)_{2} \right ]+4NaOH

During leaching, silver is oxidized when they combine with CN^{-} forming their respective soluble complex cyanide while the impurities remain unaffected which are filtered of.

(b) Where copper matte is charged into silica lined converters and hot air blast is blown the following reaction takes place,

    2FeS+3O_{2}\rightarrow 2FeO+SO_{2}

\underset{(Impurity)}{FeO}+\underset{(Flux)}{SiO_{2}}\rightarrow FeSiO_{3}(Slag)

    2Cu_{2}S+3O_{2}\rightarrow 2Cu_{2}O+2SO_{2}

    2Cu_{2}O+Cu_{2}S\rightarrow 6Cu+SO_{2}

The solidified upper obtained has blistered appearance due to evolution of SO_{2}. So, it is called blister copper.

(c) NaCH acts as a depressant that is used to prevent one type of are, i.e, ZnS from forming a soluble zinc complex, ZNa_{2}\left [ Zn(CN)_{4} \right ]

\underset{Depressant}{NaCH}+\underset{Ore}{ZnS}\rightarrow \underset{Sodium tetracarbonate}{Na_{2}\left [ Zn(CN)_{4} \right ]}+Na_{2}S

 

 

Posted by

Sumit Saini

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