When gold and silver are associated with sulphide minerals, they are often recovered with these sulphide minerals by flotation with the flotation concentrate leached to recover the precious metals or smelted to recover the precious and base metals. At Hidden Valley (HV) Mine, gravity separation is used to recover the coarse gold, followed by a bulk flotation step to recover most of the gold and silver minerals. The flotation concentrate is then leached and the gold and silver in solution are removed by a Counter Current Decantation (CCD) circuit and then recovered in a Merrill Crowe circuit. The precipitate from the Merrill Crowe circuit is calcined and smelted to produce a dore. The flotation and CCD tailings are sent to a Carbon in Leach (CIL) circuit to recover these precious metals and the carbon elution solution is sent to a separate Merrill–Crowe circuit and the precipitate is also calcined and smelted to produce a dore. The remaining cyanide in the final tailing is sent to an Inco Detox and a Caro’s Acid detox circuits, producing the main source of process water which is recycled to the upstream circuits such as grinding and flotation. At the time that this research was initiated, the Au and Ag recoveries were below the values achieved in the feasibility study. A contributing factor was the process water containing cyanide species which may have a deleterious effect on gold and silver flotation despite cyanide destruction processes. This is a common problem encountered in precious mineral processing plants (Adams, 2013).