What is Involved in extractive metallurgy?
Comminution
The first stage of a mineral processing operation is comminution, or particle size reduction. This stage of processing normally involves classification (particle size sorting) and then the crushing or grinding of the larger particles. In terrestrial operations the primary concern of the comminution circuit is that of mineral liberation, and ensuring the material is small enough to be handled in the beneficiation stage.
Beneficiation
The second major step in a mineral processing operation is the beneficiation of the (usually) comminuted material. Beneficiation processes aim to separate out the valuable minerals from the waste or 'gangue' rock. In this process the chemical or physical properties of the valuable minerals are exploited to produce one or more concentrate streams, and a gangue or waste material stream.
Metal Production
The last step in the metal extraction process is the reduction of minerals to form metal and oxygen. In terrestrial operations oxygen is ignored as a product, but in space, this oxygen is an important product to recover. The reduction of minerals can be completed using one of three main energy sources: Chemical, Electrical, and Thermal. Often a process will use multiple of these energy sources to produce a metal.