Refining Process

The metal obtained at the end of the extraction stage (Section 1.3 or 1.5, depending on the route used) is described as CRUDE metal, because it generally still carries residual impurities -- unreacted oxide/ore that failed to convert, other metals that were co-extracted, and nonmetals picked up along the way. REFINING is the name for the further processing step that removes these impurities from the isolated crude metal and delivers the pure metal. There is no single universal refining method: the right choice depends on the physical/chemical properties of the metal itself (its boiling point, melting point, tendency to form volatile compounds) and on the nature of the impurities present. The five common refining methods covered in the sub-sections below -- distillation, liquatio …