The Main Differences Between Melting and Smelting
Although the two terms melting and smelting sound similar, they are different terms that have different applications. Melting is the process of liquefying a solid substance by heating. It is the process by which a substance changes from the solid phase to the liquid phase. Smelting is the process by which a metal is obtained at temperatures beyond the melting point from its ore. Both processes involve heating a substance to a higher temperature. The main difference between melting and smelting is that melting converts a solid substance into a liquid whereas smelting converts an ore to its purest form.
Smelting is done from basic metals like iron, copper, and silver where chemicals, such as reducing agents, are used to wash out another element from ore into gas or slag.
Another way to look at it is that melting is a spontaneous process as opposed to smelting which is a non-spontaneous process. Melting is mainly done to mold an element or substance into a particular shape to use in various ways, whereas smelting is done for extracting metals like copper, iron, silver, and gold.
A good example for small recyclers: when recycling palladium and silver from Pd-Ag capacitors, as a first step we ball-mill it into a powder and then smelt it with fluxes (chemicals such as reducing agents). Results demonstrate that from 1,000 grams of Ag-Pd capacitor powder you can usually get a 130 gram metal ingot of all the metal components of the powder (Ni, Cu, Bi, Ag, Pd). The balance is composed of slag (waste).