Reduction of Metals definition of Reduction of Metals in the Free Online Encyclopedia.

Reduction of Metals

the process of producing metals from ores using reduction reactions. The reduction of metals was originally understood to be the reactions used to obtain metals from their oxides by using substances having greater affinity for oxygen than the metal. The simplest example is the production of iron from its protoxide:

FeO + C = Fe + Co

This reaction takes place, in particular, in blast furnaces.

The possibility of reducing metals is determined by the free energy of the reaction

MeO + R = Me + RO

where MeO is the metal oxide and R is the reducing agent. If in this reaction (at constant temperature and pressure) the total free energy for Me and RO is less than for MeO and R, the process proceeds from left to right, with formation of metal. The process is facilitated if the final product, which is metal, is present in the dissolved state (solid or liquid), since dissolution is accompanied by a decrease in free energy. This explains why, in the reduction of metals, some particularly stable oxides yield the corresponding alloys as end products. Thus, the reduction of metals requires the presence of a definite thermodynamic stimulus. In addition, great importance also attaches to the kinetic conditions of reduction, which are determined by crystallochemical changes (in the case of solid oxides), the mechanism of the chemical reactions at the phase boundaries, and the mass-transfer conditions for the reagents—for example, diffusion.

In a more general chemical sense, the reduction of metals consists of the addition of electrons to an atom or group of atoms. Therefore, reduction of metals also includes processes in which metals are obtained at a cathode by electrolysis of salt melts or solutions—for example, in the case of copper:

Cu⁺⁺+ 2e = Cu

where e is an electron.

In technology the most important examples of such processes are the production of aluminum by electrolysis of alumina from a melt and the production of copper from aqueous solutions of CuSO₄. In nonferrous metallurgy, reduction of metals is carried out in the production of metals from sulfides, chlorides, and other compounds. Since the electrons given off by the reducing agent are necessary for reduction, reduction processes are inseparably connected with oxidizing processes.

REFERENCES

Gel’d, I. V., and O. A. Esin. Protsessy vysokotemperaturnogo vosstanovleniia. Sverdlovsk, 1957.
Pauling, L. Obshchaia khimiia. Moscow, 1964. (Translated from English.)

L. V. VANIUKOVA and L. A. SHVARTSMAN

Mentioned in	?		References in periodicals archive	?		Encyclopedia browser	?		Full browser	?
No references found	2000) Carbothermic reduction of metals from electrolytic slurry in plasma furnace. Power consumption of liquid-phase reduction melting process by Kostyakov, V.N.; Grigorenko, G.M.; Poletaev, E.B.; Medved, S.N.; Shevchuk, E.A. / Advances in Electrometallurgy	Reducing reducing agent reducing atmosphere reducing coupling reducing flame reducing glass reducing joint reducing pipe reducing pipe fitting reducing power reducing socket reducing sugar Reducing Valve Reducing-Cooling Unit reduct reductant Reductio Ad Absurdum Reduction reduction cell reduction formula reduction gear reduction index reduction of area Reduction of Forces Reduction of Labor Reduction of Metals reduction of observations reduction of star places reduction of tidal current reduction of tides reduction potential reduction ratio reduction roll reduction rule reduction sequence reduction sphere reduction strategy reduction to sea level reduction to the meridian reduction to the sun Reduction, Photographic reductions reductive grammar Redundancy redundancy bit redundancy check redundant redundant array of inexpensive disks Redundant Array of Inexpensive Servers Redundant Arrays of Independent Disks Redundant Arrays of Inexpensive Disks	Reduction in Personnel Reduction in rank Reduction in Recordable Reduction In Recruitment Reduction in Total Ownership Cost Reduction in Workforce Reduction in Yield reduction index Reduction leukapheresis reduction mammaplasty reduction mammaplasty Reduction mammoplasty Reduction mammoplasty Reduction mammoplasty Reduction of Accidents and Aggressive and Inconsiderate Drivers Reduction of Administrative Workload reduction of area Reduction of Cardiac Operative Risk Reduction of Cholesterol in Ischemia and Function of the Endothelium reduction of chromosomes Reduction of Earthquake Losses in the Eastern Mediterranean Region Reduction of Enterprise Nutrient Discharges Project Reduction of Error Reduction of Excess Steam Emission and Air Leakage Reduction of Force Reduction of Forces Reduction of Labor Reduction of Metals reduction of observations reduction of star places Reduction of the Posterior Vertical Dimension reduction of tidal current reduction of tides Reduction on Yield Reduction Option Loan Reduction Option Loans Réduction Ouverte avec Fixation Interne Reduction potential Reduction potential reduction ratio Reduction Ratio of Viable Tumor Size Reduction reaction Reduction reaction Reduction reaction reduction roll reduction rule reduction sequence reduction sphere Reduction Strategies Reduction strategy Reduction Symmetry Method Reduction to a Previously Unsolved Problem reduction to order reduction to sea level reduction to the meridian

Mentioned in

References in periodicals archive

Encyclopedia browser

Full browser

No references found

2000) Carbothermic reduction of metals from electrolytic slurry in plasma furnace.

Power consumption of liquid-phase reduction melting process by Kostyakov, V.N.; Grigorenko, G.M.; Poletaev, E.B.; Medved, S.N.; Shevchuk, E.A. / Advances in Electrometallurgy