Gold & Silver Refiners
Refining means purifying an impure material, in this case a metal. It is different from smelting and calcination. Gold and silver refiners remove impurities and in doing so increase the value of the metal. Refining is the final stage of gold production after the smelting process. Gold and silver refiners add borax and soda ash to molten metal, separating pure gold from other precious and semi 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 then cast the gold produced during refining into bars.