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Extractive metallurgy develops processes for separating useful metals from ores and refining them to a required purity. A process may combine physical concentration, high-temperature reactions, dissolution and electrochemical recovery. The appropriate route depends on the mineral's chemical composition, the metal's reactivity and the fate of unwanted constituents.

For iron extraction, an iron oxide must lose oxygen. In a simplified reaction, $\mathrm{F}{\mathrm{e}}_2{\mathrm{O}}_3+3CO\to 2Fe+3C{\mathrm{O}}_2$, carbon monoxide is the reducing agent. Separating the resulting iron from slag and controlling remaining impurities are further tasks. Extraction is therefore a sequence of reaction and separation steps, rather than just melting the original rock.^[ref]

Metallurgy studies how to obtain metals from their source materials and control their chemical composition, microstructure and useful properties. Extractive metallurgy deals with separating and refining metals; physical metallurgy connects their internal structure to properties such as mechanical strength, ductility and electrical conductivity.

Steelmaking illustrates the connection between chemistry and materials science: removing oxygen from an iron oxide produces iron, controlling its carbon content produces different steels, and subsequent heat treatment changes the arrangement of crystal structures and hence the mechanical properties. Two samples with similar overall chemical composition can therefore behave differently because their microstructures differ.^[ref][ref]