X-ray technique may boost yield of gold mines

Working with Canadian company Mevex, CSIRO (Australia’s national science office) has conducted a pilot study that shows that gamma-activation analysis (GAA) offers the advantage of speed and accuracy over chemical analysis methods.

GAA works by scanning mineral samples – typically weighing around half a kilogram – using high-energy x-rays that activate any gold in the sample. The activation is then picked up using a sensitive detector.

According to project leader Dr James Tickner, CSIRO’s study showed that this method is two-to-three times more accurate than the standard industry technique ‘fire assay’, which requires samples to be heated up to 1200°C.

‘The big challenge for this project was to push the sensitivity of GAA to detect gold at much lower levels – well below a threshold of one gram per tonne,’ he said in a statement.

Last year, Australia produced over A$10bn worth of gold. Even if GAA only led to a five per cent improvement in recovery, that would be worth half a billion dollars annually to the industry.