Question

Which of the following statements is incorrect about the extractive metallurgy of copper?

• A. Matte formed after smelting chiefly consists of cuprous sulfide and a bit of ferrous sulfide.
• B. Most of the $Si{O}_2$ impurity is removed as fusible slag during roasting which combines with flux FeO.
• C. The copper pyrites are concentrated by the froth floatation process.
• D. FeS as an impurity is roasted to FeO which reacts with flux $Si{O}_2$ to form slag $FeSi{O}_3$ in the blast furnace during smelting and in a Bessemer Converter during self reduction.

Answer 1

The correct option is B Most of the $Si{O}_2$ impurity is removed as fusible slag during roasting which combines with flux FeO.

a) In Bessemerisation, molten matter (a mixture cuprous sulfide and ferrous sulfide) called matte is reduced and obtained after the smelting of copper pyrites in a Bessemer converter.
b) FeS is present as an impurity which is roasted to FeO which combines with $Si{O}_2$ as flux to form slag as $FeSi{O}_3.$ Thus, (d) is correct, b) is not.
c) Copper pyrites ($CuFe{S}_2$) is a sulfide ore. Thus, froth floatation is used for the concentration of the ore.
Hence, the incorrect option is (b)