Scientists use X-ray vision to search for previously hidden gold

A new X-ray method can detect gold in ore samples faster and more accurately than traditional chemical analysis methods, Australian scientists say. The technique means mining companies will be able to recover small traces of gold that would otherwise be discarded, researchers at the Commonwealth Scientific and Industrial Research Organization reported. Gold processing plants currently only recover 65 to 85 percent of gold present in mined rock, meaning traces of gold worth hundreds of millions of dollars are missed, they said. "Our experience suggests that better process monitoring can help reduce this loss by about a third," CSIRO researcher James Tickner said. The new technique, known as gamma activation analysis, uses high-energy X-rays similar to those used to treat patients in hospitals to activate any gold in an ore sample and the activation is then picked up by a sensitive detector. Last year, Australia produced more than $10 billion worth of gold, and if the new technique only led to a modest 5 percent improvement in recovery it would be worth $500 million annually to the industry, Tickner said. "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 1 gram per ton," he said. It could benefit other mining activities as well, he said. "While most of the work we've done has been based on the gold industry, the technique can be modified for other valuable commodities such as silver, lead, zinc, tin, copper and the platinum group metals."