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How pure is gold after the Miller refining process?
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The Tanami gold mine, Northern Territory, Australia.
The Miller process is a method used to refine gold by blowing gaseous chlorine into molten metal to remove impurities. While this method is valued for being rapid and simple, it produces gold with a purity level of approximately 99.5 percent.1
If a higher degree of purity is required, the Wohlwill process is typically employed, which utilizes electrolysis to achieve a purity of about 99.99 percent.1