GOLD ORE REFINING.
In gold ore refining the final stage of gold production refining involves removing impurities that remain after the smelting process. Refining companies receive doré bars, as well as scrap gold, and reliquefy the metal in a furnace. Workers add borax and soda ash to the molten metal, which separates the pure gold from other precious and less precious metals. A sample is then taken to a lab for tests, or assays, that measure the gold content. In most cases, the gold is 99.9 percent pure. Workers cast the gold produced during refining into bars