Dow Water & Process Solutions

DOWEX Resins for Separation of Osmium from Liquid Media

Osmium - Os Osmium is the heaviest element and has many important uses ranging from fountain pen tips to precision electrical contacts. Osmium (particularly Os (IV)) can be grouped with the platinum group metals (PGM) because it forms stable oxyanion complexes.

Applications

Acidic Halogen Leach: 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 downloadable information is available in Recovery of Precious Metals from Acidic Halogen Leach Solutions (364KB PDF)).

In chloride solutions osmium forms very stable chloroanion complexes which are readily adsorbed on strong base anion exchange resins such as DOWEX™ 21K XLT resins. Interestingly, the PGMs are also strongly adsorbed on weakly basic anion exchange resins such as DOWEX M-43 resins. Weakly basic anion exchangers are often effective in their conjugate acid forms (in acidic media) or in their free-base forms (neutral ligand-metal complexes). Elution of osmium from the resin can generally be accomplished with dilute acid solutions that do not elute other platinum group metals. Fuming of osmium loaded resins is not recommended as the volatile osmium can carry away other PGMs. Downloadable information on fuming is available in Recovery of Precious Metals from Acidic Halogen Leach Solutions (364KB PDF).

Caution: Osmium compounds are generally volatile (some sublime) and are extremely toxic. As with all metal solutions, those containing Os should be handled using appropriate personal protection.