In the reaction

The intermediate(s) is(are)

Copper is the most noble of the first row transition metals and occurs in small deposits in several countries. Ores of copper inculcated chalcanthite (CuSO$$_4$$ . 5H$$_2$$O), atacamite (Cu$$_2$$Cl(OH)$$_3$$), cuprite (Cu$$_2$$O), copper glance (Cu$$_2$$S) and malacite (Cu$$_2$$(OH)$$_2$$CO$$_3$$). However, 80% of the world copper production comes from the ore of chalcopyrite (CuFeS$$_2$$). The extraction of copper from chalcopynite involves partial roasting, removal of iron and self-reduction.

Partial roasting of chalcopyrite produces

Copper is the most noble of the first row transition metals and occurs in small deposits in several countries. Ores of copper inculcated chalcanthite (CuSO$$_4$$ . 5H$$_2$$O), atacamite (Cu$$_2$$Cl(OH)$$_3$$), cuprite (Cu$$_2$$O), copper glance (Cu$$_2$$S) and malacite (Cu$$_2$$(OH)$$_2$$CO$$_3$$). However, 80% of the world copper production comes from the ore of chalcopyrite (CuFeS$$_2$$). The extraction of copper from chalcopynite involves partial roasting, removal of iron and self-reduction.

Iron is removed from chalcopyrite as

Copper is the most noble of the first row transition metals and occurs in small deposits in several countries. Ores of copper inculcated chalcanthite (CuSO$$_4$$ . 5H$$_2$$O), atacamite (Cu$$_2$$Cl(OH)$$_3$$), cuprite (Cu$$_2$$O), copper glance (Cu$$_2$$S) and malacite (Cu$$_2$$(OH)$$_2$$CO$$_3$$). However, 80% of the world copper production comes from the ore of chalcopyrite (CuFeS$$_2$$). The extraction of copper from chalcopynite involves partial roasting, removal of iron and self-reduction.

In self-reduction, the reducing species is