AZTEC: a high precision automated instrument for gold assaying

AZTEC has been developed as a fully automated instrument which employs an X-ray fluorescent (XRF) technique for the analysis of gold ores, as a replacement for the existing fire assay method. A special high sensitivity detector has been developed to measure down to 0,5 ppm (parts per million by mass) gold using K X-rays. Once set up, the system can be left unattended for the analysis of up to 250 samples at a time. The use of K X-rays has the advantage over current XRF instruments (which use L X-rays) of analysing larger samples up to 100 g with a quick and easy sample preparation. The running costs of AZTEC are extremely low, with no escalating prices of chemicals and consumables. The instrument is not labour intensive, and special rooms are not required, as in fire assay. Rapid reporting is automatically carried out via the computer, and gold face profiles are updated quickly. There are no interferences from other elements but the instrument can be extended to the analysis of other heavy elements such as uranium, platinum and lead. The accuracy obtained is good down to 1 ppm gold. A manual version for measuring gold in carbon (INCA) from carbon-in-pulp plants is in development