1. Metallurgy (Occurrence And Concentration)

Metallurgy is the science and technology of extracting metals from their ores and preparing them for use. Metals are found in nature primarily as oxides, sulfides, carbonates, or halides. The first step in metallurgy is the occurrence and concentration of these ores. Ores are minerals from which a metal can be extracted economically. Concentration involves removing gangue (unwanted material) from the ore using physical methods like gravity separation, froth flotation, or magnetic separation, depending on the ore's properties.

2. Metallurgy (Extraction)

Extraction of the metal from the concentrated ore involves converting the ore into a form from which the metal can be easily separated. Common methods include: calcination (heating in the absence of air, usually for carbonates and hydroxides) and roasting (heating in the presence of excess air, usually for sulfides). These processes convert the metal compound into an oxide. The subsequent reduction of the metal oxide to the free metal is achieved through various methods, often involving smelting with a reducing agent like carbon or using electrolysis.

3. Metallurgy (Thermodynamic And Electrochemical Principles)

Thermodynamic principles, particularly Gibbs free energy changes, are crucial for selecting appropriate extraction methods. The Ellingham diagram graphically represents the Gibbs free energy of formation of metal oxides as a function of temperature, helping to predict the feasibility of reduction. Electrochemical principles are applied when electrolysis is used for extraction, especially for highly reactive metals like aluminum and sodium, where the decomposition potential of the molten salt is lower than the decomposition potential of water.

4. Metallurgy (Refining)

After extraction, the crude metal obtained is usually impure and needs further purification through refining processes. Various refining techniques are employed depending on the metal and the nature of impurities. These include distillation (for low boiling point metals like zinc), electrolytic refining (for copper, aluminum), liquation (for metals with low melting points and high melting impurities), zone refining (for very pure metals like silicon and germanium used in electronics), and chromatographic methods.