hüdrometallurgiat

Hydrometallurgy is a branch of extractive metallurgy that uses aqueous chemistry to recover and refine metals from ores, concentrates, and recycled or residual materials. It involves dissolving the desired metal or metals into an aqueous solution, followed by separation and purification steps to obtain the pure metal or a valuable compound. This contrasts with pyrometallurgy, which uses high temperatures to process metals.

The primary stages of hydrometallurgy typically include leaching, where the metal is dissolved from the solid material using chemical reagents. Common leaching agents include acids, bases, and cyanide solutions, depending on the specific metal and ore composition. Following leaching, the pregnant leach solution, containing the dissolved metal ions, is separated from the solid residue.

Next, purification and concentration steps are employed. These can involve solvent extraction, where the metal ions are transferred from the aqueous solution to an organic phase, or ion exchange, where ions are adsorbed onto a solid resin. Precipitation is another common method, used to selectively remove impurities or to recover the metal itself as a solid compound.

Finally, the metal is recovered in its elemental form or as a desired compound. Common recovery techniques include electrowinning, where an electric current is used to deposit the pure metal onto a cathode, or cementation, where a more reactive metal is used to displace the dissolved metal from solution. Hydrometallurgical processes are often favored for low-grade ores, complex mineral assemblages, and for the recovery of precious metals due to their selectivity and ability to operate at lower temperatures than pyrometallurgical methods.