The Electronic Theory of Reduction and the Extraction of Metals from Ore

Abstract

None of the existing approaches to the extraction of metals from ore can completely explain the practical findings. This suggests that reduction occurs by more than one pathway. The solid-phase reduction of metals by carbon in complex and lean iron ores from different sources and also in individual oxides of silicon, chromium, and aluminum is investigated. The electrical characteristics of ores and individual oxides are studied in order to refine theoretical concepts regarding reduction. In all cases, the reduction of metals is found to involve the conversion of the oxide’s crystal lattice into the crystal lattice of the metal. On the basis of quantum mechanics and solid-state physics and chemistry, new fundamental principles are identified in the electronic theory of the reduction of metals. Reduction consists in electron exchange between the reducing agent and the metal cations in the oxide. As a result, anionic vacancies with free electrons are formed at the oxide surface. Depending on the concentration of the cations to be reduced, the conversion of the ionic bond of the oxide’s cations to the metallic bond of the metal’s cations involves the coalescence of charged anionic vacancies at the surface of the oxide or at greater depth. This process does not require motion of the cations over considerable distances or the formation of metal atoms; the thermodynamic constraints associated with the formation of new-phase nuclei do not apply. This theory is able to explain all the known experimental results regarding the solid-phase reduction of metals in oxides: the formation of continuous metallic shells at the surface of pieces of rich iron ore; the deposition of metal particles within lean and complex ores; and the formation and sublimation of suboxides. In the deposition of metallic phase within the complex oxide, there is no direct contact between the metal and reducing agent; therefore, in the reduction of iron in complex or lean ores by carbon, no sulfur or carbon is transferred to the metallic phase from the reducing agent. In the reduction of such ore, fuel coal may be used as the reducing agent. The product is a metal–oxide composite containing pure iron and valuable oxides of magnesium, titanium, and vanadium.