Metallurgical Processes

Zone refining (or zone melting) is a technique used to purify metals by moving a molten zone through the material, which carries impurities along with it.

Roasting is a metallurgical process where sulfide ores are heated in the presence of excess air. Calcination, by contrast, involves heating in the absence or limited supply of air.

Zone refining is a highly effective method for purifying semiconductors like silicon and germanium to the extremely high levels of purity required for electronic applications.

Highly reactive metals like sodium are obtained by the electrolysis of their molten salts (electrometallurgy) because they cannot be reduced by common chemical reducing agents.

Metallurgy is the branch of science and technology concerned with the properties of metals and their production and purification from ores.

Extraction is the general term for the process of obtaining a metal from its ore through various chemical and physical methods.

Highly reactive metals have a strong affinity for oxygen and cannot be reduced by carbon; therefore, they are extracted by the electrolysis of their molten salts.

During electrolysis, positive metal ions are attracted to the negatively charged electrode, which is the cathode, where they gain electrons to become neutral metal atoms.

Highly reactive metals like potassium, sodium, and calcium are extracted from their molten chlorides via electrolysis because they are too reactive to be reduced by carbon.

Aluminium is extracted from its ore, bauxite, which is primarily aluminium oxide, through the Hall-Heroult process involving electrolysis of molten oxide.

Calcination is the process of heating an ore strongly in the absence of air to convert carbonates into metal oxides. Roasting, by contrast, involves heating in the presence of excess air.

Manganese and chromium oxides are reduced to their respective metals using aluminium powder as a strong reducing agent; this is a thermite-type reaction.

The reduction of metal oxides by aluminium is highly exothermic, meaning it releases a significant amount of heat, often enough to keep the metal in a molten state.

The reduction of metal oxides using aluminium powder as a reducing agent is specifically referred to as the thermite reaction.

Roasting is the process of heating a sulfide ore in the presence of excess air to convert it into a metal oxide.