Idrometallurgia

Idrometallurgia, or hydrometallurgy, is a chemical technique used to extract metals from their ores or recycled materials by using aqueous solutions. It differs from pyrometallurgical processes, which rely on high temperatures to separate metals. In idrometallurgia, the ore is first comminuted and then leached with water containing one or more soluble reagents such as acids, bases, or complexing agents. The metal ions dissolve into the solution, forming an electrolyte that can be processed further.

The leaching step typically involves a combination of physical and chemical actions. Physical actions include grinding and fine‑ming to increase surface area, while chemical actions involve the addition of leaching agents that break the bonds between metal atoms and their host minerals. Common leaching agents are sulfuric acid, nitric acid, cyanide, or thiourea, depending on the target metal and ore characteristics. For some ores, bioleaching—a method that uses microorganisms to oxidize metal sulfides—can also be employed.

After dissolution, the metal‐bearing solution undergoes concentration, purification, and recovery. Techniques such as solvent extraction, ion exchange, precipitation, electrowinning, or adsorption are used to separate and concentrate the metal. Electrowinning, for instance, passes an electric current through the solution, causing the metal to deposit onto cathodes. The recovered metal can then be cast or fabricated into usable form.

Idrometallurgy offers several advantages: it operates at lower temperatures, reduces energy consumption, and allows the processing of low‑grade ores that would be uneconomical for pyrometallurgy. It also enables the recycling of electronic waste, where complex alloys can be selectively dissolved and recovered. However, the process requires careful handling of chemicals and water resources, as the effluents can contain hazardous substances that must be treated before discharge.