Separation of Iron from Liquid Media

26

Fe

Cyanidation Mining

Today, most gold is mined by the cyanide leaching or cyanidation process. Use of anion exchange resins to sorb the gold from the pregnant solution has long been common practice in the gold mines of the former Soviet Union, and its advantages are now recognized more broadly.

Dow produces DOW™ XZ 91419.00 Developmental Anion Resin, a gold-selective resin specifically designed for use in resin-in-pulp and pump-cell processing. For information on how to use DOW XZ 91419.00 in gold mining applications, contact Dow.

When a highly-selective resin is not required, DOWEX™ 21K XLT Strong Base Anion Resin can be used to capture the gold since gold extracted by cyanidation is in the form of anionic aurocyanide complex (Au(CN)2-). Elution from the resin can be achieved with a more strongly adsorbed anion; zinc cyanide or thiocyanate are commonly employed.

If NaOH is the desired eluent to recover the gold from the resin matrix, then AMBERLYST™ A21 Weak Base Anion Resin should be chosen.

NOTICE: If products, such as DOW™ XZ 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.

Acid Halogen Leach

Many mining projects are underway in which ores are leached under oxidizing and acidic conditions. Under these conditions, Dow’s anion exchange resins, such as DOWEX™ 21K XLT Resin, 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.

Plating Baths

Dow’s anion exchange resins, such as DOWEX™ 21K XLT Resin, are commonly used in the recovery of gold from spent plating bath solutions. Generally, the loaded resin will absorb up to 60 oz of gold per cubic foot (60 g/L) and the gold is recovered by thermal decomposition (fuming).

Additional information regarding the recovery of precious metals by fuming can be provided by contacting Dow.

Gold has been valued for its beauty, malleability and non-corrosive properties for millennia. Gold mining operations are improving their economics out of financial necessity and innovations in gold hydrometallurgy are emerging on a regular basis as operations trim down. Dow has long been at the forefront of many of these new developments with the commercial use of Dow's ion exchange resins in the primary recovery of gold in mining operations.