Question

The methods for extracting metals from their ores are:

1. roasting a metal sulphide

2. chemical reduction of a metal oxide

3. electrolysis,

The preferred method depends on $E^{\circ }$ value for the reducing half-reaction:

$M^{n+}\left(aq\right)+n{e}^{-}\to M\left(s\right)$

Which method is preferred for the metals with the most positive $E^{\circ }$ values?

Answer 1

Roasting is a step of the processing of certain ores.
Roasting is a metallurgical process involving gassolid reactions at elevated temperatures with the goal of purifying the metal component(s). Often before roasting, the ore has already been partially purified, e.g. by froth floatation. The concentrate is mixed with other materials to facilitate the process.
If $E^o$ is most positive for a metal than it will have least tendency to reduce and we will use roasting method to extract metal from its ore.