The EMS^® method of cyanide water treatment can both separate and concentrate the precious metals component of a feed water for resource recovery. The EMS^® separation of precious metals from base metals-contaminated solutions is especially important because it allows for the direct recovery of high-purity precious metals by conventional carbon or zinc processing, in lieu of the poor recovery of base metals-contaminated precious metals by these same methods without EMS^® treatment.

The removal of base metal cyanide salts to a small-volume fraction of a PLS stream further enables the recovery of the base metals by, for example, electrowinning or precipitation. The metals recovery also enables recovery of the cyanide that was previously complexed with the base metals. This metals and cyanide recovery mode of operation is revolutionary with regard to the cyanide treatment of copper 'cyanicidic' ores.

A new generation of refractory gold hydrometallurgical processes is evolving around the oxidative treatment of gold-bearing sulfides in resource recovery. Of special note is the bio-oxidation method, wherein acid liquors high in zinc, copper, iron and arsenic are generated. These liquors can be bleed-stream EMS^®-treated to prevent the build-up of metals to bio-toxic levels while concurrently co-producing clean acid for re-use in the process. In addition, the EMS^® treatment can be further engineered for the recovery of saleable metals by conventional electrowin, precipitation or cementation processes. The bio-oxidized ore or concentrate would be traditionally cyanide treated.

The resource recovery of cyanide for re-use in lieu of end-of-the-pipe destruction can be EMS^® affected for both WAD-CN and CN_FREE. In the case of WAD-CN, the EMS^® method optionally includes the removal of WAD-metal by either precipitation or electrowin means and the creation of by-product revenue streams. In the case of CN_FREE recovery, the reagent can be returned directly to the gold dissolution circuit.

When WAD-CN and CN_FREE are removed from a solution, the cyanide destruction burden is lessened and a low-cyanide-content permeate is produced that can be used in a variety of ways, as might be required, for the washing of spent ore or concentrate before disposal as a 'dry tail.'

Applications

Precious Metals