Distillation is not a common method of metal refining as it is primarily used for separating liquids based on their boiling points.

The primary goal of metal refining is to extract pure metals from ores by removing impurities and other unwanted elements.

Pyrometallurgy involves the use of high temperatures to melt and separate metals from impurities. It is commonly used for refining metals such as iron, copper, and aluminum.

Electrorefining involves passing an electric current through a molten electrolyte to separate metals. It is commonly used for refining metals such as copper, silver, and gold.

Hydrometallurgy involves using chemical reactions in aqueous solutions to extract and purify metals. It is commonly used for refining metals such as copper, zinc, and nickel.

Fluxing is the process of removing impurities from the surface of a metal using a flux, which is a chemical substance that combines with the impurities to form a slag that can be easily removed.

Gas refining involves passing a gas, such as chlorine or hydrogen, through a molten metal to remove impurities by forming volatile compounds that can be easily removed.

The purpose of adding a slag former during metal refining is to remove impurities from the metal by forming a slag, which is a molten mixture of impurities that can be easily separated from the refined metal.

Nitrogen is not a common impurity found in metal ores as it is a relatively inert gas that does not readily form compounds with metals.

Biometallurgy is the process of refining metals using microorganisms, such as bacteria and fungi, to extract and purify metals from ores.

Zone refining involves repeatedly melting and solidifying a metal to remove impurities by creating a molten zone that moves along the metal, pushing the impurities to one end.

Annealing is a heat treatment process used in metal refining to improve the ductility of the metal by reducing internal stresses and promoting grain growth.

Oxidation refining involves the selective oxidation of impurities in a molten metal by adding an oxidizing agent, such as oxygen or air, to convert the impurities into oxides that can be easily removed.

Electrorefining is the process of removing impurities from a metal by electrolysis, in which the metal is dissolved in an electrolyte and an electric current is passed through the solution to deposit the pure metal on the cathode.

Salt bath refining involves immersing the metal in a molten salt bath, which acts as a medium for removing impurities by dissolving them or forming compounds that can be easily separated.