Precious Metal Recovery Using Bidentate Ligands

摘要

For the last four years, Lynntech has been developing a cost effective procedure for extracting and purifying PGM's from acid solutions. This technology could be used as a unit process step in an overall hydrometallurgical process for the extraction of PGMs from mined ores, or the recovery of spent PGM catalyst from used catalyzed substrates. Our process is extremely effective, in particular for the extraction of platinum and palladium from aqueous acid solutions, also containing a high concentration of base metals. Major advantage of using diquat materials will be the efficiency and a higher degree of selectivity for binding PGMs in the presence of other base metal ions in solution. Diquats designed in this invention have been substituted heavily with hydrophobic alkyl chains which make these insoluble in acidic solutions. This process essentially consists of four steps whereby solid can be contacted with aqueous solutions of PGMs and base metals under suitable conditions allowing PGMs to be selectively bound to the diquaternary materials leaving base metals in the aqueous solutions. This is followed by separation of the aqueous stream containing mainly base metals. Solid materials can then be washed to remove any physically trapped metal ions. Pure PGMs can be recovered from the solid matrix after incineration. The biggest advantage of using these bidentate ligands as solid extractents is that the process does not need huge quantities of solvents required for solvent extraction process. This makes the process environmentally friendly and cost effective.