A new method to help Australia's gold processors has been developed by scientists working in the Parker Centre.

CSIRO Minerals' Ron Pleysier explained the problem was residual ‘frothers' that poisoned carbon and reduced its ability to recover gold in the carbon-in-leach (CIL) process.

"Measuring the impact of these poisons on the carbon is not difficult. However, finding the amount in solution that can be tolerated before gold loss occurs requires an accurate method to measure specific organics in slurry in the parts per million range,” Pleysier said.

"Till now, the industry could not be sure how much organic was entering the slurry and contaminating the carbon. Our new method measures the organic with precision. This enables CIL plant managers to control reagent additions and reagent recycle to prevent the carbon being fouled.”

The research found that tighter control of frother additions to reduce residual organics by little as 5-10 ppm was sufficient to substantially eliminate the problem.

"We also found that frother decomposition products can foul carbon and the process is significantly more complicated than the scientific literature suggests," Pleysier said. "Recirculating water means that the stability of the reagents and the loading kinetics of both the frother and daughter products can have a major impact on gold losses. To minimise losses you need to be able to manage this process with precision.”

The new tests, together with detailed process models developed in the Parker Centre, mean that CIL circuit can be checked by Parker Centre staff to make sure companies are recovering as much gold as possible.

By Julian Cribb, Senior Editor, ScienceAlert.
First published in Australia’s Mining Monthly in April 2006 as part of a longer feature in the Cutting Edge features series.