Cast iron is used for the manufacture of

In the blast furnace,the reduction of iron oxide is carried out by which of the following?

In the metallurgy of zinc,the zinc dust obtained from roasting and reduction of zinc sulphide contains some $ZnO$. How is this removed?

During the smelting of roasted copper ore,silica is added to remove:

The main reactions occurring in a blast furnace during the extraction of iron from haematite are $....$.
$(i)$ $Fe_2O_3 + 3CO \to 2Fe + 3CO_2$
$(ii)$ $FeO + SiO_2 \to FeSiO_3$
$(iii)$ $Fe_2O_3 + 3C \to 2Fe + 3CO$
$(iv)$ $CaO + SiO_2 \to CaSiO_3$

Explain electrometallurgy in detail.