Question

Mention the role of silica during the extraction of copper from copper pyrites.

Answer 1

Hint: Just try to recall the process involved in the extraction of copper from copper pyrites. There an impurity is formed during the process and silica has some very important role in that. Now you can easily answer the question explaining all things.

Complete step by step answer:

Now let’s discuss the complete role of silica during the extraction of copper from copper pyrites.

$2CuFeS_{ 2 }\quad +\quad O_{ 2 }\quad \rightarrow \quad Cu_{ 2 }S\quad +\quad 2FeS\quad +\quad SO_{ 2 }$
$2Cu_{ 2 }S\quad +\quad 3O_{ 2 }\quad \rightarrow \quad 2Cu_{ 2 }O\quad +\quad 2SO_{ 2 }$
$2FeS\quad +\quad 3O_{ 2 }\quad \rightarrow \quad 2FeO\quad +\quad 2SO_{ 2 }$

We can see in these equations, there are three main products during this process, those are $SO_{ 2 }$, FeO, and $Cu_{ 2 }O$. Here sulfur dioxide is easily removed because it is a gas. Copper oxide we need for extraction of copper so we need to remove iron oxide. Hence, we can say during the roasting of pyrite ore, a mixture of FeO and $Cu_{ 2 }O$ is obtained.

The role of silica in the metallurgy of copper is to remove the iron oxide (FeO) obtained during the process of roasting as 'slag'. If the sulfide ore of copper contains iron, then silica ($SiO_{ 2 }$) is added as flux before roasting. Then, FeO combines with silica to form iron silicate, $FeSiO_{ 3 }$, which is known as slag.

Therefore, we described the role of silica during the extraction of copper from copper pyrites.

Note: The commonest ore used in the extraction of copper is Chalcopyrite ($CuFeS_{ 2 }$) also known as Copper Pyrites and other such sulfides. The percentage of copper in the actual ore is too low for the direct extraction of copper to be viable. The concentration of ore is required and it is done by the Froth Flotation Method.