Remove iridium, ruthenium and osmium from 90% to 99.50% gold bar. (No replies)

S
shaurytheseth
3 years ago
shaurytheseth 3 years ago

Currently we are refining raw god(old jewelry) using silver and nitric acid, and are able to achieve purity of 99.50%, but are not able to remove trace amounts of iridium, ruthenium and osmium. Fire assay method gives purity of approx. 99.50%, but XRF analysis gives us a purity of 96% to 99.5%. I have read many forums, which suggests refining gold with aqua regia. What should we do to refine raw gold and remove minor platinum group metals? 

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