PRE-CONCENTRATION & ORE SORTING
PFTNA uses an electrical tube to provide a pulsed flow of neutrons that interacts with the nuclei of the atoms in the passing material . In response , the atoms emit gamma rays at characteristic energy levels . These gamma rays are measured with scintillation detectors and high-speed electronics to collect the spectrum of emitted gamma rays , with the spectra interpreted and the elemental concentrations determined
and the elemental concentrations determined .
Rajendra Mishra , Product Manager for Malvern Panalytical ’ s Cross-Belt Analyzers ( CNA ), said the “ bulk analysis ” benefits that come with this
neutron-based technology – able to direct 14 million electron volts onto the conveyor belt – allow mining companies to get a true picture of the mineral composition of material on a conveyor belt .
“ When compared with the traditional Californium-252 neutron source for prompt gamma neutron activation analysis ( PGNAA ) – which offers roughly 2.5 million electron volts – we are able to detect much smaller concentrations of minerals and metals ,” he told IM .
Such characteristics fit the needs of many base metal operators suffering from grade depletion , hence the reason why Metso signed up to a nonexclusive collaboration agreement with Malvern Panalytical back in 2022 to provide high-speed , sensor-based bulk ore sorting solutions to the mining industry .
It is also the reason why many miners – major copper and nickel producers included – are already leveraging Malvern Panalytical ’ s conveyor-based solutions , which it provides through its ties with SODERN , a subsidiary of the Ariane Group , the largest aerospace company in Europe and the second largest worldwide .
Neutron-based solutions continue to prove effective on the ‘ bulk analysis front ’, but there is an amount of reticence from new customers around the perceived safety issues that come with potential radiation exposure .
Uwe König , Head of Business Development for the Mining and Metals team at Malvern Panalytical , said these safety concerns have risen up the agenda following the heavily documented radioactive capsule loss that occurred in Western Australia in 2023 .
“ One advantage of PFTNA is we are using an electrically-operated neutron tube that has an on-off mechanism to ensure neutrons are not emitted when the unit is switched off ,” he said . “ Most operations also have safety fences around installations to ensure personnel are not exposed to radiations by inadvertent entry .”
In addition to these comprehensive safety precautions , Malvern Panalytical follows a stepwise approach to applying its solutions at mine sites . This sees it calibrate its sensors with the help of representative material samples from the client , testing the solution at laboratory and pilot scales and then carrying out a full-scale implementation verified through further labbased testing .
The ability to move from ore analysis to ore sorting using PFTNA is one that requires more than just Malvern Panalytical and SODERN ’ s input ; it also requires a solutions provider able to ‘ actuate ’ the sort with a matching speed . This comes back to the Metso agreement . König said : “ We came together with Metso as we worked with them on other solutions , and it was very much a case of ‘ one plus one equals three ’. They had sorters , we had sensors and the combination was a great fit to approach customers on a joint basis .”
The two companies have been carrying out testing on several projects in the mining space and are confident of this leading to commercial installations .
In the meantime , Malvern Panalytical can reflect on successful tests with a major mining company on an ‘ open format ’ PFTNA sensor mounted after the primary crusher to carry out elemental analysis of rocks up to 300-400 mm in size for oxide and sulphide differentiation ; on proxy-based precious metal detection ; and potential in tailings management , heap leaching and metal recycling applications .
König added : “ We also see the digitalisation trend with sensor readings where customers want to measure all the ore on the belt and predict the energy needed to process this material later on , or the water required for processing .”
This is likely to see PFTNA sensors working alongside other sensors backed by analysis from AI-based algorithms to solve the major challenges the industry faces .
On that front , Malvern Panalytical is well prepared , working on the potential to integrate a Near Infrared ( NIR ) sensor into this mix , having an awareness of what Metso is proposing across the wider flowsheet with the separate agreement the OEM has with TOMRA Mining on particle sorting , and making plans to adapt some labbased software and maintenance platforms for its CNA customers in the field .
Scantech on the PGNAA value drivers
Henry Kurth , Chief Marketing Officer of Scantech International , has previously referred to bulk sensing as a ‘ digitalisation tool ’ that generates data to be used simultaneously for multiple applications .
Such a reference emerged while highlighting Scantech ’ s GEOSCAN-M PGNAA-based sensing solutions , which have been used for decades by the mining sector – in coal , iron ore , phosphate and about a dozen other commodities . These systems measure the elemental composition continuously in real time , through the full conveyed cross section so the entire flow can be representatively measured . Unique advantages of the GEOSCAN-M are that it is proven on belts containing steel cords and chlorine ( such as FRAS rated belts used underground ) and measures ores such as potash containing high chlorine levels or those with rare earth elements , the company says .
All GEOSCAN-M installations are conveyorbased and are custom-configured to specific applications that determine the frequency and precision of the results , according to Kurth . “ It tends to be more frequent and higher precision in bulk sorting , a little less frequent for normal measurement , and possibly longer for blending control ,” he said .
For any of these applications , the value of the data comes by providing a better understanding of ore and waste quality variability over short timeframes and tonnages compared with larger tonnages in shovels and trucks and very much larger tonnages in orebody block models and blast designs , Kurth explains .
“ The high-resolution data from the short , conveyed parcels provides opportunities for improved selectivity and fine tuning of decisions to influence the grade received by the process
58 International Mining | MARCH 2024