Purification and processing of the (semi-)finished product

Leaching is rarely selective. The solution contains impurities that can interfere with the production of the desired metal or compromise its purity. It is therefore necessary either to purify the solution resulting from the leaching step in a purification step, or to selectively extract the metal species of interest while leaving the impurities in solution during a selective extraction step. During this step, the metal species can be extracted one by one to separate them and produce a pure metal salt, for example by precipitation. The techniques used to extract, separate, or purify are mostly the same as those used to produce the semi-finished or finished product. In this section, we will present the main unit operations used to extract, separate, purify, and produce the (semi-)finished product, without making any specific distinction.