Merrill-Crowe process
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Merrill-Crowe process
(′mer·əl ′krō ′prä·səs)
(metallurgy) Removal of gold from cyanide solution by deoxygenation followed by precipitation on zinc dust, the work being completed by filtration to give the resultant auriferous gold slimes.
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Merrill-Crowe process
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Merrill-Crowe process
The Merrill-Crowe Process is a separation technique for removing gold from a cyanide solution.
The solution is separated from the ore by methods such as filtration and counter current decantation (CCD) and is then clarified in special filters, usually coated with diatomaceous earth to produce a clarified solution.[1] Oxygen is then removed by passing through a vacuum de-aeration column. Zinc dust is then added to the clarified, de-aerated solution which precipitates the gold; zinc having a higher affinity for the cyanide ion than gold. Silver and copper will also precipitate, if present.
The gold precipitate is then filtered out of the solution, mixed with fluxes, and smelted to form crude and impure bars. These bars are sent to a refinery to remove the copper and silver, the specific process used depending upon the impurities in the gold.[2]
The basic process was discovered and patented by Charles Washington Merrill around 1900, and later refined by Thomas B. Crowe, working for the Merrill Company.
In more recent years, the EMEW technology has started to replace this process through the use of electrowinning
See also
- Other Gold cyanidation techniques:
- Carbon in pulp
- Electrowinning
- Resin in pulp
References
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