Question

Describe the role of the following:
(i) $Si{O}_2$ in the extraction of copper from copper matte.
(ii) $NaCN$ in froth floatation process.

Answer 1

(i) In the extraction of copper from copper matte, $Si{O}_2$ reacts with iron oxide to form slag of ferrous silicate and is removed.
$FeO+Si{O}_2\to FeSi{O}_3$
(ii) In froth floatation process, to separate PbS and ZnS from ores, NaCN is used as depressant. It selectively prevents ZnS from coming to the froth and PbS is removed along with the froth.