Extraction of Crude Metal

Once the ore has been concentrated (Section 1.2), the next stage is extracting the actual CRUDE metal from it. This extraction is always carried out in exactly two steps, in this fixed order: (i) CONVERSION of the concentrated ore into an oxide of the metal of interest, and (ii) REDUCTION of that metal oxide down to the free (elemental) metal.

The reason the sequence always goes through the oxide as an intermediate, even when the ore is not already an oxide ore, is thermodynamic: in the concentrated ore, the metal exists in a positive oxidation state (combined as a sulphide, carbonate, oxide or similar), and reduction of an OXIDE to the free metal is, thermodynamically, generally easier and more favourable than direct reduction of other compound classes such as sulphides or carbonates. Consequently, whatever chemical form the concentrated ore is originally in, it is standard practice to first …