Selective Removal of Mercury from Gold Bearing Streams
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Many gold ore bodies contain high levels of mercury which are co-extracted with the gold. This mercury then travels through the process circuit to pose health, environmental and technical issues. This article highlights a method to selectively remove the mercury whilst leaving the gold to be processed as normal. The removal of mercury from the circuit mitigates the need for retorting of the produced gold, reduces the potential environmental impact of any waste solutions and decreases any potential mercury exposure to plant workers.
The solid bound thiol species used have been shown by inductively coupled plasma optical emission spectrometry (ICP-OES) to reduce the mercury to undetectable levels whilst having no measurable effect on the gold concentration. The control of the cyanide concentration at the adsorption step has been shown to be key to ensuring that the mercury removal is achieved selectively. This in turn ensures that no precious metal value is lost in the mercury removal process. The process has been shown to be applicable to both batch and continuous operation which will allow the technology to be applied to a variety of flow rates and applications.