Atom Minerals initiated an assay program on a 1.3 million tonne tailings dam with a view to understanding why previous attempts at recovering viable quantities of gold had been unsuccessful.
There are three important parameters in tailings dam reclamation projects:
Previous sampling and testing showed a gold head grade of 1.3 g/t and recovery of 23%, meaning that a reprocessing project was not viable.Significant sampling and test work revealed that the preg-robbing characteristics of organic carbon particles, evenly distributed throughout the dump, were at least partially responsible for this poor recovery. A gold assay on a collection of carbon particles collected indicated a head grade of over 400 g/t.The first step in solving the recovery problem was to find a method of separating the carbon particles from the siliceous (sandy) material. This is a common problem in gold processing which occurs when carbon particles escape through a safety screen into a tails dam.
Many methods have been tried previously to solve this issue including:
None of these methods produced any detectable separation, despite academic papers claiming they would be successful. Collaboration with some of the papers’ authors revealed that some of the methods presented had not met with practical or economic success due to process complexity.Using a new hydrophobic binder reagent technology developed at the University of Newcastle, Atom carried out significant testwork with tailings samples, and was able separate and concentrate the carbon particles in a laboratory, and is now working with the University on a larger scale to produce a commercially viable process.
