Modern Mining February 2019


Revolutionary X-ray technology finds gold faster

thyssenkrupp Industrial Solutions South Africa has been appointed as the offi- cial reseller of the ground-breaking PhotonAssay technology from Chrysos Corporation, headquartered in South Australia. Novel X-ray technology is poised to revolutionise the field of gold analysis, replacing traditional methods such as fire-assay in many applications. Chrysos Corporation’s PhotonAssay provides accurate and fully automated gold mea- surements in mineral ores in just a couple of minutes. The world-first PhotonAssay unit, installed in a commercial Perth laboratory, recently passed twin milestones, complet- ing its first 50 000 analyses and receiving ISO 17025 accreditation. The owner of MinAnalytical Laboratory Services will establish a major new analytical facility in early 2019 providing PhotonAssay services in Kalgoorlie, the heart of Australia’s gold mining industry. “For our customers, it means the sys- tem has been validated and fully tested, and they can rest assured they will receive accurate results which have been benchmarked against fire assay,” said MinAnalytical’s General Manager Gary Wheeler. Originally developed by scientists at the CSIRO, Australia’s national research agency, PhotonAssay uses high-power X-rays to activate and measure gold atoms in mineral samples. Compared to conven- tional X-ray fluorescence, the much higher energies used in PhotonAssay allow true- bulk measurements of large samples that are

designed for rapid deployment to both centralised and mine-site laboratories anywhere in the world. Systems are fully containerised, allowing them to be fully factory tested and then packaged for shipping and on-site installation. The modular design of the PhotonAssay unit lends great flexibility. In addition to on- site installations, thyssenkrupp also has the capabilities to run the lab from its Johannesburg head office. “As we are the face of this technology in Africa, we can sell the technology to exist- ing laboratories or directly to a customer,” notes Combrinck. He adds that thyssenk- rupp will provide after-sales service and support to customers and end-users on the continent. The X-ray source used is fully elec- tronic and contains no radioisotopes. PhotonAssay units comply with inter- national safety standards and due to their high levels of automation can be operated by staff with minimal training. Combrinck adds that management of the PhotonAssay unit requires only two staff members, freeing up personnel who can attend to other tasks. The potential for near real-time gold assays is generating strong interest in on- site installations. With a typical detection limit of 0,03 parts-per-million, a measure- ment time of 2-3 minutes and the ability to measure crushed ore, process pulps, con- centrates, carbon materials and solutions with equal facility, amine-site PhotonAssay unit can provide rapid information to sup- port resource definition, mine-planning and process control. A throughput

independent of their physical or chemical form. Marius Combrinck, thyssenkrupp Product Manager RT Sales and Marketing Minerals, explains how the PhotonAssay technology works: “PhotonAssay hits samples with high-energy X-rays from a linear accelerator. These X-rays force any gold atoms present in the sample into an excited state that lasts for a few seconds. Subsequently, a sensitive detector system measures the gamma-ray signals given off by these atoms as they relax. Processing software relates the gamma-ray signature back to the gold concentration.” Combrinck points out that the gamma- ray energy is different for each element, allowing gold to be accurately distin- guished from other metals that may be present. Samples to be assayed are packaged into standardised plastic jars which are sealed and barcoded. They remain in the jars throughout the analysis process. As the method is non-destructive, samples are returned unchanged and can be safely handled, disposed of or sent for further testing as required. The large sample size – typically about 500 g – significantly reduces sample prep- aration requirements. Recent testing has demonstrated that – for most materials – crushing samples to 2-3 mm is sufficient to enable accurate sampling and analysis. For coarse gold deposits, the 10-fold increase in sample size compared to conventional fire-assay is particularly advantageous. PhotonAssay units are

of more than 1 600 samples per day provides enough capacity for even the largest opera- tions. A significant reduction in skilled labour requirements is an additional benefit for remote sites.

PhotonAssay units are designed for rapid deploy- ment to centralised and mine site laboratories anywhere in the world.

Although developed pri- marily for gold analysis, the PhotonAssay technology is capable of measuring a wide range of other elements. Silver and copper assay services will be added during 2019 and extension to other metals is planned for this year. thyssenkrupp Industrial Solutions (South Africa), website:

40  MODERN MINING  February 2019

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