Lithium Universe (ASX:LU7) reports >99% gold recovery from GCDE technology
Lithium Universe has reported further laboratory results from testing of its licensed Gold Copper Diamide Extraction, or GCDE, technology developed by the University of Edinburgh.
The program examined selective gold recovery from complex multi-metal chloride solutions, the influence of solution chemistry on metal selectivity, reagent recyclability and production of a metallic gold product.
Highlights
Gold precipitation from chloride solution exceeded 99%, with residual dissolved gold of 2 to 6 ppm.
Metallic gold produced after reduction assayed 97.04% purity.
Gold recovery from dissolved e-waste reached 98%.
No organic solvents were required and the ligand was recyclable.
At 2M hydrochloric acid, iron, tin and platinum recovery was minimal, while copper, nickel, zinc and palladium recovery was negligible.
The latest investigations followed the successful demonstration of GCDE for selective gold recovery from chloride solutions.
Lithium Universe commissioned the work to better understand the operating characteristics and commercial potential of the technology, with the objective of optimising process performance by evaluating leach chemistry, metal selectivity, gold recovery and the quality of the final metallic gold product.
Testing focused on the ability of the proprietary diamide reagent to selectively precipitate gold from complex multi-metal chloride solutions containing dissolved base and precious metals commonly encountered in mineral processing and recycling applications.
Varying hydrochloric acid concentrations were also investigated to assess selective recovery while leaving other dissolved metals in solution or recovering them in a controlled sequence.
The program evaluated conversion of the recovered gold precipitate into metallic gold using a conventional reduction process.
Gold precipitation was observed in hydrochloric acid and aqua regia systems, and reduction using sodium metabisulphite produced metallic gold assaying 97.04% purity.
Further testing examined recyclability of the diamide reagent over multiple loading and stripping cycles and its application to dissolved electronic waste.
Under 2M hydrochloric acid conditions, gold was recovered almost quantitatively while aluminium, copper, nickel, zinc, palladium, iron, tin and platinum remained largely in solution.
At 6M hydrochloric acid, the test results recorded high recovery of iron, tin and platinum, while copper, nickel, zinc and palladium recovery was negligible at both 2M and 6M hydrochloric acid.
The GCDE process uses a proprietary diamide reagent that selectively binds dissolved gold species under acidic chloride conditions to form an insoluble precipitate.
Once separated from solution, the gold is released by washing with deionised water, allowing recovery of dissolved gold and regeneration of the reagent for repeated use.
The precipitation mechanism differs from traditional solvent extraction because the reagent directly captures gold within the aqueous phase.
Developed by the University of Edinburgh’s School of Chemistry with support from Edinburgh Innovations, GCDE is designed to recover gold and copper from electronic waste using selective, reusable organic reagents.
The process uses a diamide compound to selectively precipitate gold from acidic leach solutions, followed by copper recovery using pyrazine-2,3-dicarboxylic acid (PDCA).
Lithium Universe Chief Executive Officer Iggy Tan said,
“We look forward to advancing the technology towards pilot-scale development and commercialisation.”
Lithium Universe states that the latest results mark a further validation step towards pilot-scale demonstration and commercialisation.
The announcement identifies the global precious metals recovery market from e-waste at approximately US$11.8bn in 2025, with gold representing the largest and highest-value component.