Question

(i) Name the method of refining to obtain silicon of high purity.
(ii) What is the role of $Si{O}_2$ in the extraction of copper?
(iii) What is the role of depressants in froth floatation process?

Answer 1

(i) Zone Refining is the method of refining to obtain silicon of high purity.

(ii) $Si{O}_2$ combined with the iron in the copper ore to from iron (II) silicate slag which is easily removed.

$FeO+Si{O}_2⟶FeSi{O}_3$

(iii) In froth flotation process, depressant prevents the formation of froth. It is used to separate two sulphide ore and allowing the other to form the froth, e.g., $NaCN$ a depressant selectively $ZnS$ from coming in froth but allows $PbS$ to come with the froth.