PhotonAssay™ – Efficient & bulk gold analysis in the modern world

Abstract

The Chrysos PhotonAssay™ Max is an instrument utilising high-energy X-rays but reimaged for the modern world with full robotics and ability to keep up with the high demands of mining. Since Pierre Gy’s introduction of sampling theory into the gold mining industry, many researchers have struggled with limitation of the available techniques, like fire assay and cyanide leach, and their impact on the fundamental errors in relating the assay value to the drill hole or deposit. Gold provides some unique sampling challenges over other commodity elements as it is malleable and is difficult to homogenise by pulverisation. By analysing a sample size 10 times that of a traditional fire assay, the sample variance is often decreased providing immediate benefit to the geologists, as predicted by sampling theory. By reducing the sample preparation down to the 3 mm crush, there is also an immediate benefit in cost and time savings. Statistical tests show that the analysis on the 3 mm product size by PhotonAssay™ is similar to the traditional analysis by fire assay, suggesting the two techniques can be used interchangeably during a drilling program. This paper describes some of the tests we have done to give the industry confidence that this technique provides immediate benefit and can be used to compare to historical fire assay data.