The Group IIIB elements of scandium, yttrium, and lutetium readily lose their three outer shell electrons to form +3 ions in solution. The aqueous ions of M3+ are hydrolyzed in water to the common form of [M(OH)(H2O)n-1]2+. The Lanthanide series also forms these same ions so they exhibit similar separation chemistries.
Many mining projects are underway in which ores are leached under oxidizing and acidic conditions. Under these conditions, DOWEX™ Anion Exchange Resins have proven to be tough, steady performers.
Additional information about the recovery of precious metals from acidic halogen leach solutions can be provided by contacting Dow.
When precious metals are used as heterogeneous or homogeneous catalysts, part of the metal can be lost to the process resulting in further uncontrolled reaction, quality issues, and higher costs due to the lost metal value. These metals can be recovered with an ion exchange resin scavenger.
In many cases DOW™ XUS 43600.00 Developmental Thiouronium Resin does an excellent job of loading platinum and palladium. In other matrices, a thiol-functionalized resin such as AMBERSEP™ GT74 Resin can provide a more effective solution. In strong brine solutions, DOWEX™ 21K XLT Resin should be tested. In many cases AMBERLYST™ A21 Resin does an excellent job of loading platinum and palladium; this weak base anion resin is effective under neutral to acidic conditions.
With any of these options, the ion exchange resins can be regenerated or sacrificed to recover the metal. Precious metal loaded resins can also be processed by catalyst suppliers to recover lost metals.
To recover precious metals from organic solvent-based streams, AMBERLYST™ A21 DRY Resin is also effective, but the resin should be used dry. Non-aqueous exchange kinetics are slower so adequate contact time must be provided. For more information on resin preparation see Processing Organic Solvents.
DOWEX™ Anion Exchange Resins are commonly used in the recovery of platinum and palladium from spent plating bath solutions. Generally, the loaded resin will absorb up to 60 oz of metal per cubic foot (60 g/L) and the metal is recovered by thermal decomposition (fuming).
Additional information regarding the recovery of precious metals by fuming can be provided by contacting Dow.
Dow offers a thiouronium-functionalized resin designated DOW™ XUS 43600.00 Developmental Thiouronium Resin. The resin is a macroporous, uniform particle size product which has good exchange kinetics and is highly selective for PGMs. It is a tough and rugged product for resin in pulp applications. Note that the thiouronium group is subject to base hydrolysis so the product should be used under acidic to neutral pH conditions.
NOTICE: If products, such as DOW™ XUS products, are described as “experimental” or “developmental”: (1) product specifications may not be fully determined; (2) analysis of hazards and caution in handling and use are required; (3) there is greater potential for Dow to change specifications and/or discontinue production; and (4) although Dow may from time to time provide samples of such products, Dow is not obligated to supply or otherwise commercialize such products for any use or application whatsoever.