The Wohlwill process is an industrial-scale chemical procedure used to refine gold to the highest degree of purity (99.999%).
Lower percentages of gold in the anode will interfere with the reaction, especially when the contaminating metal is silver or one of the platinum group elements.
Current is applied to the system, and electricity travels through the electrolyte of chloroauric acid.
When the anode is dissolved, the cathode is removed and melted or otherwise processed in the manner required for sale or use.
When lower purity gold is required, refiners often utilize the Miller process for its relative ease and quicker turnaround times and because it does not require a large inventory of gold, in the form of chloroauric acid.