Can Vanta Portable XRF Measure Gold (Au) to Less than 20 Parts per Billion?

By Todd Houlahan - 15 czerwiec, 2022

Yes, it is possible. Gold concentrations to less than 20 parts per billion (ppb) can now be detected by portable XRF. On-site, anywhere.

Evident is pleased to be part of the launch of Portable PPB’s detectORE^TM technology. detectORE provides gold explorers and miners with same-day, low-level gold measurements using Vanta™ portable XRF analysis. This innovation enables fast, reactive decision-making in the field for quicker discovery and development of gold deposits.

Gold exploration and discovery using portable XRF analysis

detectORE technology provides same-day gold results to dramatically speed up gold exploration

detectORE applies to all types of geological samples. After licensing this CSIRO-invented technology in 2018, Portable PPB has spent the last three years testing over 20,000 lab-analyzed samples and certified reference materials to create a robust, quality-controlled method that measures low-level gold using a portable XRF to a high level of confidence.

Gold analysis using portable XRF, aqua regia, and fire assay

Grade control samples were analyzed for gold using different methods: detectORE technology, aqua regia, fire assay, and cyanide leach.

Disrupting the Gold Industry with a Faster Way to Discover Gold Deposits

Portable XRF analyzers, also known as pXRF, typically obtain lower limits of detection (LOD) to single digit parts per million (ppm) on many transition elements of the periodic table. For instance, the gold (Au) LOD is 1–3 ppm for our Vanta handheld XRF analyzers.

Yet, this LOD for Au is usually too high to be effective on its own for gold exploration, as gold generally occurs in very low concentrations. That’s why most gold explorers and miners rely on pathfinder elements when using pXRF. A pathfinder element is closely related to the gold deposit being sought. These include arsenic (As), copper (Cu), lead (Pb), zinc (Zn), antimony (Sb), tungsten (W), and bismuth (Bi).

Another challenge of gold exploration using pXRF is interference from other elements. Au sits in a very crowded area of the energy spectrum. False-positive results for Au can occur if samples contain arsenic (As), zinc (Zn), tungsten (W), platinum (Pt), and selenium (Se).

detectORE paves a new way forward by tackling these challenges.

Portable PPB’s detectORE technology overcomes the detection limit issue by leaching the Au from the sample and concentrating it on a collector device. Further, Evident worked closely with Portable PPB to develop customized calibrations to address the spectral overlap issues. Portable PPB’s proprietary techniques interpret the pXRF signal and return an accurate Au result to the customer for the samples tested, down to levels <20 parts per billion (ppb).

Gold concentration of different certified reference materials using portable XRF analysis

detectORE technology was tested on a wide range of certified reference materials

From Proof of Concept to R&D—Finalizing the Design Using Portable XRF

During the detectORE proof-of-concept stage, CSIRO used our DELTA™ handheld XRF analyzer exclusively. From 2018 to 2021, Portable PPB relied on four of our Vanta handheld XRF analyzers for their research and development on samples from around the world. Extensive studies were performed using these Vanta analyzers, and data to be published by MRIWA (Minerals Research Institute of Western Australia) in the coming months shows instrument-to-instrument repeatability was found to be outstanding.

Testing as part of this program was also performed to evaluate the Vanta analyzer’s ability to withstand extreme temperatures. The Vanta analyzer’s data stability was again, outstanding.

Evident is proud to say we invested in Portable PPB’s success from the very start of their amazing journey. We look forward to supporting Portable PPB and all future detectORE users with Vanta analyzers to help fast-track discovery and development of gold deposits well into the future.