Industrial & Real-world Applications of Metallurgy

Blast furnace (iron production) is one of the world's largest industrial reactors. Pig iron from the blast furnace contains ~4% carbon — further refined in a basic oxygen furnace to make steel.
Hall-Heroult electrolysis is the sole industrial route for aluminium production globally. It is extremely energy-intensive (~15 kWh/kg Al), driving demand for cheap hydroelectricity near smelters.
Bessemer converter (copper extraction) was also the original route for steel from pig iron. The self-reduction principle (sulphide reduces its own oxide) eliminates external reductant cost.
Electrolytic refining of copper is essential for electrical-grade copper (99.99% pure), used in wiring and electronics. The anode mud from copper refining is a significant source of commercial gold and silver recovery.
Zone refining supplies ultra-pure silicon (>99.9999%) for semiconductor chips and solar cells. Without zone refining, modern electronics would not exist.
Mond process is used industrially for nickel refining at Clydach (UK) and Sudbury (Canada). Carbon monoxide recovered in the decomposition step is recycled, making the process economical.
Froth flotation is the backbone of the sulphide mining industry worldwide. The use of selective depressants (NaCN for ZnS) allows separation of multiple metals from polymetallic ores.
Leaching with NaCN (gold extraction) is widely used but environmentally controversial due to cyanide toxicity. Modern plants neutralise spent cyanide with $SO_{2}$ /air or hydrogen peroxide.
Bayer's process produces ~90% of the world's alumina. Red mud (iron oxide residue) is a major solid waste challenge for the aluminium industry.
Cryolite solvent in Hall-Heroult dramatically reduces energy costs. Natural cryolite (Greenland) is nearly exhausted; synthetic $Na_{3}AlF_{6}$ is now produced from HF and alumina.
Flux and slag chemistry in iron making allow selective removal of silica (acidic gangue) and provide a liquid medium for impurity separation, critical for producing usable pig iron.
Van Arkel method produces reactor-grade titanium and zirconium for nuclear reactors, aerospace, and medical implants, where ultra-high purity is non-negotiable.