Hydrometallurgy

Hydrometallurgy encompasses the extraction and recovery of metals through aqueous chemistry, offering a complement to energy-intensive pyrometallurgical routes. Core operations include leaching—where acids, bases or specialised lixiviants dissolve target metals from ores, concentrates or secondary materials—followed by separation of impurities via precipitation, solvent extraction or ion exchange, and concluding with recovery steps such as cementation or electrowinning. The method excels in treating low-grade, complex or secondary resources (for example spent catalysts, battery sludge and electronic waste), and operates at moderate temperatures and pressures. By tailoring reagent chemistry and process conditions, hydrometallurgy achieves high selectivity for desired metals while minimising energy consumption and environmental impact. Recent advances focus on sustainable reagent regeneration, integration of novel sorbents and catalysts, and real-time monitoring to enhance solvent life, reduce effluent volumes and respond to stringent supply-security demands for strategic and critical metals worldwide.

Research from Nature Portfolio

Regenerable covalent organic frameworks have been engineered with robust sp²-carbon backbones and amidoxime sites to achieve simultaneous fluorescence-based detection and high-capacity uranyl uptake. These materials exhibit rapid response times under two seconds, exceptional chemical and radiation stability, and uptake capacities exceeding 400 mg g⁻¹, enabling on-site monitoring alongside extraction. Bio-inspired porous nano-traps mimic protein-like second-sphere interactions by incorporating chelating and assistant groups into rigid frameworks. They reach more than 500 mg g⁻¹ in uranyl adsorption, maintain performance in natural seawater and reveal the synergistic roles of hydrogen bonding and coordination in enhancing selectivity. DNAzyme-derived hybrid hydrogels form specific ‘nano-pockets’ that bind uranyl with high affinity and discriminate against competing ions in seawater, achieving binding capacities around 6 mg g⁻¹ and selectivity factors near 19, thus broadening biopolymer applications in radionuclide recovery.

Research from all publishers

A minireview of porous nanomaterials demonstrates that carbon-based supports, covalent and metal–organic frameworks furnished with amidoxime and heteroatom sites can remove hexavalent uranium via synergistic sorption and photocatalysis. Tunable pore structures and single-atom active sites afford high surface areas, while electron-donor–acceptor constructs markedly improve selectivity. In parallel, N-doped polymeric carbon nitride, activated by persulfate, generates radical species under visible light to achieve 100 % photoreduction of uranyl to U(IV) within 20 minutes, offering rapid treatment of contaminated waste streams. Another study combines polymeric carbon nitride with iron oxide in a two-dimensional/zero-dimensional S-scheme heterojunction to leverage internal electric fields for efficient charge separation. Under mild photo-enhanced conditions, over 90 % of U(VI) is removed from reprocessing effluents and recovered as U(IV), even in the presence of high concentrations of competing cations and organics, pointing to scalable strategies for spent-fuel wastewater remediation.

Hydrometallurgy publication trend

The graph below shows the total number of articles in hydrometallurgy across all publications each year (not limited to Nature Index journals).

Technical terms

Hydrometallurgy: The extraction of metals from ores or secondary materials using aqueous solutions, typically involving leaching, purification and recovery stages.

Leaching: The process of dissolving metal-bearing compounds from solid matrices into a liquid phase by contact with a solvent.

Solvent extraction: A separation technique in which metal ions transfer from an aqueous phase into an organic phase containing selective extractant ligands.

Uranyl (UO₂²⁺): The most prevalent hexavalent uranium species in solution, characterised by a linear O=U=O coordination.

Amidoxime: A chelating functional group (–C(NOH)NH₂) that forms strong complexes with uranyl ions and is widely used in uranium adsorbents.

Photocatalysis: A light-driven process in which a semiconductor material generates electron–hole pairs that mediate redox reactions, such as reducing U(VI) to U(IV).

Electrocatalysis: The acceleration of electrochemical reactions at an electrode surface, facilitating selective oxidation or reduction of metal ions under applied potential.

References

1. Hydrometallurgy.
2. Regenerable and stable sp2 carbon-conjugated covalent organic frameworks for selective detection and extraction of uranium. Nature Communications (2020).
3. Bio-inspired nano-traps for uranium extraction from seawater and recovery from nuclear waste. Nature Communications (2018).
4. DNA nano-pocket for ultra-selective uranyl extraction from seawater. Nature Communications (2020).
5. Highly selective removal of U(VI) from aqueous solutions by porous nanomaterials. EcoEnergy (2024).
6. Rich electron delocalization structure in carbon nitride inducing radical transfer for high‐performance photocatalytic uranyl reduction. Carbon Energy (2024).
7. Photo‐enhanced uranium recovery from spent fuel reprocessing wastewater via S‐scheme 2D/0D C3N5/Fe2O3 heterojunctions. SusMat (2024).