ORE SORTING
elemental analysers , X-ray coal ash moisture analysers and XRF online ore pulp grade analysers to measure and report the critical elements in the mineral separation process , feeding this data back to a PLC or intelligent control system in the processing plant .
HOT Industries concluded : “ With the above minerals quality / elements measuring and reporting technologies , the whole minerals sorting system will be more reliable and intelligent to avoid the hysteresis of manual measurement .”
NextOre shifts MR gears
The last few years have been significant for Australia-based NextOre and its MR technology . It has surpassed previous throughput highs using its on-conveyor belt solutions , accelerated the decision-making process associated with material sorting viability with its mobile bulk sorter and made strides to branch out into the inpit sorting space via the development of open geometry sensors .
NextOre ’ s MR technology is the culmination of decades of research and development by the Commonwealth Scientific and Industrial Research Organisation ( CSIRO ), with the division spun out from the organisation in 2017 . Since then , NextOre has gone on to demonstrate the technology ’ s viability across the globe .
NextOre ’ s MR analysers were first fitted on conveyor belts , yet interest in solutions for in-pit equipment predates the company ’ s inception .
“ A significant portion of the time when CSIRO would show people the technology they were working on for fitting on a conveyor belt , many would ask : ‘ could you possibly put it around a truck somehow ?’,” Chris Beal , CEO of NextOre , told IM .
After workshopping many ideas and developing increasingly large prototypes – commencing at the start with an antenna made up from a copper loop and a couple of capacitors – two in-pit solutions leveraging CSIRO ’ s opengeometry sensor have come to the fore .
The first – a 3-m-wide sensor – underwent static and dynamic tests using chalcopyrite copper ore grade samples in a material feeder setup in 2022 , in Australia .
This test work , observed by several major mining companies , laid the groundwork for a bigger installation – a 7-m-wide ruggedised antenna that weighs about 5 t . This can be positioned over a haul truck and manoeuvred using a crane supplied by Eilbeck and guidance systems developed for NextOre by CSIRO and the University of Technology Sydney .
The advantage of MR in a truck load scanning scenario , just as with a conveyor , is the ability to make accurate , whole-of-sample grade measurements at high speeds . Yet , to operate effectively , this system requires significant amounts of power .
“ The truck system we are building is between 120 kW and 200 kW ,” Beal said . “ For people in the radio frequency space , power of that magnitude is hard to comprehend ; they ’ re used to dealing with solutions to power mobile phones .”
For reference , a NextOre on-conveyor system rated up to 5,000 t / h has around 30 kW of installed power . And conveyor systems above 5,000 t / h have 60 kW of installed power .
The idea is that this new MR truck sensor station would be positioned at an ex-pit scanning station to the side of the main haul road at a site and trucks will be directed to ore or waste as a result . The test rig constructed in NextOre ’ s facility has been built to suit the truck class of the initial customer , which is a major copper mine using 180-t-class and 140-t-class haul trucks .
The first prototype has now been built and , at the time of going to press , was awaiting shipment to the mine where a one-year trial is set to commence .
The scale has also recently increased with NextOre ’ s conveyor-based installations .
Around 10 months ago , IM reported on a 2,800 t / h MR ore sorting installation at First Quantum Minerals ’ Kansanshi copper mine in Zambia , which had just shifted from sensing to sorting with the commissioning of diversion hardware .
Now the company has an ore sensing installation up and running in Chile that has a capacity of 6,500 t / h – a little over 50 % higher than the highest sensing rate ( 4,300 t / h ) previously demonstrated by the company at Newcrest ’ s Cadia East mine in New South Wales , Australia .
Beal said the unit has been up and running since December , with the copper-focused client very happy with the results .
For those companies looking to test the waters of ore sorting and sensing , arguably the biggest
The truck sensor test rig constructed in NextOre ’ s facility has been built to suit the truck class of the initial customer , which is a major copper mine using 180-t-class and 140-tclass haul trucks
development coming out of NextOre in recent years has been the construction of a mobile bulk sorter .
Able to sort 100-400 t / h of material on a 900- mm-width conveyor belt while running at 0.3-1 m / s , these units – one of which has been operated in Australia – is able to compress the timeline normally associated with making a business case for ore sorting .
“ As people can now hire such a machine , they are finding it either resolves a gap in proving out the technology or it can be used to solve urgent issues by providing an alternative source of process feed from historical dumps ,” Beal said . “ They want to bring a unit to site and , after an initial configuration period , get immediate results at what is a significant scale .”
Such testing has already taken place at Aeris Resources ’ Tritton copper operations in New South Wales , where the unit took material on the first surface stockpile taken from an underground mine .
While this initial trial did not deliver the rejection rate anticipated by Aeris – due largely to rehandling of the material and , therefore , a reduction in ore heterogeneity ahead of feeding the conveyor – Aeris remains enthusiastic about the technology and Beal is expecting this unit to be redeployed shortly .
“ We now know thanks to results from Kansanshi , Carmen Copper Corp / CD Processing , this new Chilean site and Cozamin ( owned by Capstone Copper ) that this in-situ grade variability can be preserved , and that mixing impacts directly on sorting performance ,” Beal said . “ Even so , we have seen really good heterogeneity persist in spite of the unavoidable levels of mixing inherent in mining .”
He concluded : “ People want this type of
44 International Mining | MARCH 2023