Indicate the principle behind the method used for the refining of zinc. What is the role of silica in the extraction of copper?

(i) Zinc is a metal having a low boiling point and it is refined by distillation, a method used for metals with low boiling points. (ii) During the extraction of copper, FeS or FeO is present as an impurity. Therefore, SiO2 is added as a flux to form silicate (slag), which can be easily removed as it floats over molten copper (Cu). (iii) Wrought iron is the purest form of commercial iron.