Hydrometallurgiassa

Hydrometallurgiassa is a branch of metallurgy that uses aqueous chemistry to extract and recover metals from their ores, concentrates, and recycled materials. It involves dissolving the desired metal into an aqueous solution, followed by separation and purification steps, and finally recovering the metal from the solution. This contrasts with pyrometallurgy, which uses high temperatures.

The process typically begins with leaching, where the ore or concentrate is treated with a chemical solution, often acidic or alkaline, to dissolve the target metal. Common leaching agents include sulfuric acid, hydrochloric acid, cyanide, and ammonia, depending on the metal and the ore composition. Following leaching, solid-liquid separation techniques, such as filtration or sedimentation, remove the undissolved gangue material.

The dissolved metal is then purified and concentrated. Solvent extraction is a common method, where a specific organic solvent selectively extracts the metal ions from the aqueous phase. Ion exchange resins can also be employed for similar purposes. Precipitation is another technique, where the metal is caused to form an insoluble solid from the solution, which can then be filtered out.

Finally, the purified metal is recovered. Electrowinning, an electrochemical process, is widely used to deposit the metal onto a cathode. Cementation, where a more reactive metal displaces the target metal from solution, and precipitation as a compound are other recovery methods. Hydrometallurgiassa is often favored for its ability to process low-grade ores, its lower energy consumption compared to pyrometallurgy, and its potential for producing high-purity metals. It is extensively used in the processing of copper, gold, zinc, nickel, and uranium.