High Purity Precious Metals

摘要

The demand for high purity precious metals beganwith certain industrial applications having uncompromisingrequirements for quality and performance. As industrial usesproliferated and as the jewelry industry became increasinglysophisticated, the demand for high purity gold has reached thepoint where 99.99 precent is now the standard in the marketplace.A similar evolution is expected for other precious metals.In this paper, we examine both the production and use of highpurity precious metals, specifically gold, silver, platinum andpalladium. After defining what is meant by "high purity", wediscuss the various analytical techniques used for measuringimpurity concentrations. Next, we review process strategiesemployed by extractive metallurgists to produce high purityprecious metals. Lastly, we describe some of the principalapplications for high purity materials including thick films, thinfilms, bonding wire, thermocouples and jewelry manufacture.Precious metals have unique physical properties that, despitetheir expense (and the ever-continuing search for more economicalalternatives), make substitution difficult if not impossible. Thesephysical properties are dramatically affected by smallconcentrations of certain impurities. As long as manufacturerscontinue to demand quality and performance, there will be a needfor high purity precious metals.