What is the role of silica in metallurgy of copper?

Hint: Smelting is generally a technique called metallurgy technique which is used to extract base metals from their ores with the help of heat and a chemical reducing agent. Copper Smelting defines that the concentrated ore is heated strongly with silicon dioxide known as silica, calcium carbonate and air in a furnace.

Complete step by step answer:
The major steps involved in the extraction of copper are: Copper in Chalcopyrite i.e. $CuFe{{S}_{2}}$ is reduced to copper sulphide represented by $C{{u}_{2}}S$ then calcium carbonate $CaC{{O}_{3}}$ is added as a flux to create the slag and iron present in chalcopyrite is removed as iron silicate slag and then most of the sulphur present in chalcopyrite turns into Sulphur dioxide represented by $S{{O}_{2}}$.
The reaction of these processes can be defined as
$2CuFe{{S}_{2}}+2Si{{O}_{2}}+4{{O}_{2}}\to C{{u}_{2}}S+2FeSi{{O}_{3}}+3S{{O}_{2}}$
During the roasting of pyrite ore i.e. $Fe{{S}_{2}}$ then a mixture of $FeO$ and $C{{u}_{2}}O$ is obtained. The role of silica in the metallurgy of copper is to remove the iron oxide obtained during the process of extraction of pure copper from copper pyrite, $Si{{O}_{2}}$ acts as acidic flux which combines with iron oxide $FeO$ to form iron silicate $FeSi{{O}_{3}}$.

Note: Copper is defined as an outstanding conductor of electricity and combined with the property of ductility i.e. property of metal to withdraw in wires and it is the perfect metal to make electrical wiring used in both domestic and industrial. The copper extracted from this process is mixed with the slag and is called Matte Copper due to its texture and appearance.