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DOWEX Resins for Separation of Silver from Liquid Media
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Silver is the 66th most abundant metal in the Earth's crust and used heavily in the photographic, electronic, and ornamental metal industries. In nature, silver is often associated with other metals and, in fact, much of the silver that makes its way into the world market is co-produced as a by-product of the mining processes for other metals like copper, zinc, and lead. Most silver is mined in Mexico, Peru, Canada, Australia, and the United States.
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Applications
Mining and Plating: Ion exchange resins are not heavily employed in the conventional mining of silver. Some smaller gold and platinum facilities employing strongly acidic leach techniques, however, use DOWEX™ 21K XLT strong base ion exchange resins to capture ionic silver.
Photographic: The most common use for ion exchange resins in the photo processing industry is for recovery of silver from photo-processing wash waters. High silver recoveries can often be achieved by employing strong base anion exchange resins like DOWEX 21K XLT. Others have found higher loading capacities with a weak base resin like DOWEX M-43 resin. Elution of the silver from the loaded resin is often best accomplished using several bed volumes of ammonium thiosulfate followed by a brief 5% sulfuric acid regeneration. Special attention is required to make sure that silver does not reduce to the sulfide form while on the resin. Entrapped silver sulfide precipitate may require the destruction of the resin for effective recovery of the silver values.
Various cations have different affinities (24KB PDF) for strong acid cation exchange resins.
DOWEX Ion Exchange Resins
| Product |
Description |
Type |
Matrix |
Total
Exchange
Capacity*
eq/l (kgr/ft3) |
Available
Forms |
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DOWEX 21K XLT
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Uniform particle size, high capacity, strong base anion exchange resin for mineral processing applications. |
Type I Strong Base Anion |
Styrene-DVB, Gel |
1.4 |
Cl- |
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DOWEX M-43
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Corrosion control with DOWEX M-43 ion exchange resin. |
Weak Base Anion |
Styrene-DVB, Macroporous |
1.55 |
FB (Free Base) form |
®™* Trademark of The Dow Chemical Company ("Dow") or an affiliated company of Dow
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