Researchers from the University of Adelaide, Australia, have developed a portable method for gold detection that will allow mineral exploration companies to detect lower concentrations of gold on-site at the drilling rig than existing portable instruments.
Using light in two different processes − fluorescence and absorption − the researchers from the University’s Institute for Photonics and Advanced Sensing (IPAS), have been able to detect gold nanoparticles at detection limits 100 times lower than achievable under current methods.
Australia is the world’s second largest gold producer, worth $13 billion in export earnings. Not just used for jewellery, gold remains in high demand for electronics and medical applications around the world.
To estimate the quantity of gold deep underground, rock particles from the drilling holes are analysed. However, existing instruments used for portable detection are not sensitive enough, and it can take weeks to obtain results from more sensitive tests.
‘This easy-to-use sensor will allow fast detection right at the drill rig with the amount of gold determined within an hour, at much lower cost,’ said postdoctoral researcher Dr Agnieszka Zuber, working on the project with Associate Professor Heike Ebendorff-Heidepriem.
The technique employed by the portbale instrument involves adding a special dye to the liquid samples before they are tested. A blue laser is then used to shine light through the sample, and if the sample contains gold nanoparticles, a green light can be observed. This green light is then analysed to determine the quantity of gold in the sample.
The researchers have been able to detect less than 100 parts per billion of gold in water, and are now testing rock taken from a mine outside of Adelaide.