Gold mines process ore using various techniques to produce an alloy composed primarily of gold and silver, which is called a dore bar. The composition of dore can vary significantly between mines, Dore bars are first weighed and melted to ensure the metal is homogenous, that is, that there are no pockets of high or low purity within the bar. A sample is taken from this melted dore and assayed to determine the exact amount of gold and silver present.The miner then receives an outturn, which is a statement indicating the weight of the dore bar, the percentage of gold and silver in the bar, and from these two, a calculated amount of pure gold and silver. Miners will then either sell this pure gold and silver for cash, or request a loco swap. The dore bar then becomes the property of the refiner. The dore bar first goes through a chlorine refining process, also known as the Miller process. This involves bubbling chlorine gas through the molten dore metal in which the silver (and most other metals) react with the chlorine to form silver chloride as a slag on top. This process produces gold to a purity of 99.5%.

If there is demand in the market for higher purity gold, then the 99.5% pure gold from the chlorine refining process. The anodes are placed into a bath of hydrochloric acid and an electric current is passed through it, which causes the gold to dissolve and then deposit on a cathode at purity of 99.99%.