1. Principle of hydrometallurgy

Hydrometallurgy consists of a succession of chemical operations characterized by the dissolving of a metal and its production from this solution. It mainly comprises the following steps, which are separated by solid/liquid separation operations in some cases:

• leaching : metal dissolution;

• purification : extraction from the solution of impurities other than the desired metal;

• production of desired metals.

Solution purification is not always necessary, if the ore or waste treated contains few or no soluble impurities. In many cases, refining of the metal produced is essential, in order...