thyssenkrupp Industrial Solutions South Africa says it has been appointed the official reseller of ground-breaking PhotonAssay™ technology from Chrysos Corp.

The novel X-ray technology is poised to revolutionise the field of gold analysis, replacing traditional methods such as fire-assay in many applications, and providing accurate and fully-automated gold measurements in mineral ores in just a couple of minutes.

The world-first PhotonAssay unit, installed in a commercial Perth, Western Australia laboratory, recently passed two milestones; completing 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.

MinAnalytical’s General Manager, Gary Wheeler, said: “For our customers, it means the system has been validated and fully tested, and they can rest assured they will receive accurate results which have been benchmarked against fire assay.”

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 with conventional X-ray Fluorescence, the much higher energies used in PhotonAssay allow true-bulk measurements of large samples independent of their physical or chemical form, the company said.

Marius Combrinck, thyssenkrupp Product Manager RT Sales and Marketing Minerals, explained how the PhotnAssay 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 pointed out that the gamma-ray energy is different for each element, allowing gold to be accurately distinguished from other metals that may be present.

Samples to be assayed are packaged into standardised plastic jars that are sealed and barcoded, remaining 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,” thyssenkrupp said.

The large sample size – typically about 500 g – significantly reduces sample preparation requirements. Recent testing has demonstrated that for most materials, crushing samples to 2-3 mm is enough to enable accurate sampling and analysis. For coarse gold deposits, the 10-fold increase in sample size compared with conventional fire-assay is particularly advantageous, according to the company.

PhotonAssay units are designed for rapid deployment to both centralised and mine site laboratories anywhere in the world. Systems are fully containerised, allowing them to be factory tested and then packaged for shipping and on-site installation.

The modular design of the PhotoAssay unit lends great flexibility. In addition to onsite installations, thyssenkrupp also has the capabilities so run the lab from its Johannesburg head office. “As we are the face of this technology in Africa, we can sell the technology to existing laboratories or directly to a customer,” Combrinck said. He added that thyssenkrupp will provide after-sales service and support to customers and end users on the continent.

The X-ray source used is fully electronic and contains no radioisotopes. PhotonAssay units comply with international safety standards and, due to their high levels of automation, can be operated by staff with minimal training, according to thyssenkrupp. Combrinck added that management of the PhotoAssay unit requires only two staff members, freeing up personnel to 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 measurement time of two to three minutes and the ability to measure crushed ore, process pulps, concentrates, carbon materials and solutions with equal ability, a mine site PhotonAssay unit can provide rapid information to support resource definition, mine planning and process control, thyssenkrupp said.

A throughput of more than 1,600 samples per day provides enough capacity for even the largest operations, while a significant reduction in skilled labour requirements is an additional benefit for remote sites.

Although developed primarily for gold analysis, the PhotonAssay technology can measure a wide range of other elements. Silver and copper assay services will be added during 2019 and an extension to other metals is planned for this year, thyssenkrupp said.

The company plans to discuss PhotonAssay technology on February 5 and February during its three-day thyssenkrupp Technology Sessions held alongside Mining Indaba 2019.