Merrill–Crowe process
[1] The solution is separated from the ore by methods such as filtration (e.g. vertical leaf type clarifier filters) and counter current decantation (CCD).Afterwards a very clear solution is achieved by using pre-coated filters applying diatomaceous earth.[2][3] Automated membrane filtration offers a cost savings alternative to CCD.The solution is filtered, and the remaining solids are smelted to a gold dore bar.These bars are sent to a refinery to remove the copper and silver, the specific process used depending upon the impurities in the gold.