ABSTRACT
Smelting is a major processing operation aimed at extracting metals from their original ores and rening them into the composition required by the users. The engineering and scientic accomplishments required to realize this are too complex to deal with here. However, we should cite the basic principles that underlie the production of metals by smelting because this information often relates to the selection and application of such metals. The ores of metals, except for gold and a small fraction of the Cu and Ag supply, are not metallic phases. These are most commonly oxides or suldes. Copper, silver, lead, and zinc suldes are signicant sources of those metals. In either case, the metal must be extracted from its ore. Even when the ore is a sulde MS, where M is the metal ion and S is the sulde ion, it is common to rst oxidize the ore to MO. The prime extraction step is one of reduction. The ease with which reduction occurs varies from metal to metal, depending on the reduction energy required. For example, lead oxide, PbO, and silver oxide, Ag2O, reduce readily to metallic lead and silver, whereas it requires an input of considerable energy to affect the reduction of aluminum Al2O3. The reaction energy released (oxidation energy) as the metal burns to form oxide is exactly the same amount of energy which is required (reduction energy) to separate oxygen to form the metal. These energies considerably decrease as the melting temperature of the metal is approached.
