Direct recovery of precious metals by solvent extraction and selective removal

摘要

The direct recovery of precious metals, particularly gold and the platinum group metals, from chloride solutions, is achieved by solvent extraction and selective stripping/precipitation. Substituted quinolines are used as active extractant, in particular alkyl substituted 8-hydroxyquinoline. Gold is precipitated either by hot water, or by hydrogen after a cold water wash. Palladium remains in the organic phase and is precipitated by more severe hydrogen reduction or is stripped with acid. Platinum (and other precious metals) is stripped into water (the aqueous precipitant or wash), and can be recovered by hydrogen reduction (in stages). The organic phase is not degraded providing acid is washed out before any hydrogen reduction, and can be recycled.