REPROCESSING & RETREATMENT
Hidden value
As companies look to replenish their reserves of highlyvalued metals in line with an expectation of commodity demand rising , the options for reprocessing or retreating ‘ waste ’ streams continue to find favour . Dan Gleeson speaks to some of the pioneers facilitating this
Mining operations are recognising the value of mineralogical data in 2D and 3D forms for fact-based decision making , ZEISS ’ Eddy Hill says
“ The reprocessing and retreatment of mined materials is key to sustainable mining and , as such , is a focus area for ZEISS when we consider how our solutions are applied in this field ,” Eddy Hill , Manager , Business Sector , Natural Resources at ZEISS Microscopy , told IM .
A company that has provided microscopebased solutions – both hardware and software – ZEISS has spotted an opening for applying its solutions to the challenges the industry faces extracting value from some of these ‘ waste streams ’.
“ The retreatment of mined materials with the philosophy of recovering everything is opening opportunities for new product streams that may move us beyond mining and as far as the construction materials sector ,” Hill said . “ Here too we have solutions to help with the assessment of the suitability and properties of materials .”
Essential to any mineral processing is the knowledge of the mineralogy present and its interrelationships , Hill states . This , at the end of the day , is a geometallurgical problem .
“ Viewed as such we provide a suite of rock analysis solutions based on the light microscope ( LM ), the scanning electron microscope ( SEM ) and the X-ray microscope ( XRM ) – because not everyone is asking the same question of their samples , and the answer cannot always be obtained with an SEM ,” Hill says .
Sometimes the most suitable tool may be an LM , an XRM , or even a combination of microscopes , meaning the correlation between such instruments and the data exchange platforms are crucial .
“ At the core of our range of solutions there is automated mineralogy ,” Hill says .
With LM , ZEISS is applying artificial intelligence – deep-learning algorithms to segment ( classify ) the mineralogy and provide measurements , based on well know petrographic techniques .
With SEM , ZEISS has its Mineralogic 2D platform , a more traditional automated mineralogy solution , albeit based on full chemical analysis of the sample .
The XRM comes with Mineralogic 3D , which , according to Hill , is the solution the mining industry is least familiar with but which delivers volumetric mineral segmentation and measurement for an entire sample , not just the surface of the sample as is the case with the more traditional 2D techniques .
“ No one solution can answer every question ,” he says , giving the example of mineralogy on the LM coming with a fast turnaround but lacking
chemical information . With Mineralogic 2D , there is higher resolution , allowing operators to
discern phases down to nm-scale , as well as the advantage of obtaining a full chemical analysis of each grain . “ As good as the information we obtain in 2D is , it cannot beat Mineralogic 3D when it comes to grade and liberation measurements and , of course , when working with X-rays , nothing can hide beneath the surface or within a particle ,” Hill said . “ Today , the ability to auto segment mineralogy with the LM and XRM are unique to ZEISS .”
And this ability is having a tangible impact on process flowsheet selection , according to Hill .
“ Established mining operations have actively used Mineralogic to re-design their flowsheets and even add new streams to their operations ,” he said . “ This is testament to the value that mining operations are placing in mineralogical data for their fact-based decision making .
“ Going forwards , we expect an increase in the number of operations that will apply automated mineralogy information , be it on LM , SEM or XRM , to their mine design evaluations . After all , we may mine for metals , but we are working with minerals , and we gain a deeper understanding of the processes to implement for efficiency and sustainability only when we predict how the minerals will behave .”
He concluded on the subject : “ Not every legacy mine or reprocess stream may be practical for the resource we at first envision , but with detailed knowledge of the mineralogy , the interrelation of the phases and the structure of the stockpile , an educated decision can be made as to what the value is , and how best to recover it .
“ Ultimately , environmental and social imperatives will encourage the recovery of all value material , from gold , through chalcopyrite for copper , to quartz for construction .”
EnviroGold to build NVRO processing hub
EnviroGold Global is a true believer in such a metal / mineral recovery environment and is looking to enable the global mining industry to monetise valuable metals contained in mine waste and tailings including gold , silver , copper , zinc and nickel .
The company recently provided an update on its plans to demonstrate and commercialise its proprietary leaching technology – the NVRO Clean Leach Process .
It has now entered into an agreement to purchase an integrated metal processing plant developed at the Commonwealth Scientific and Industrial Research Organisation ’ s ( CSIRO ) Australian Minerals Research Centre in Perth , Western Australia , that , it says , is ideally suited , with minor modification , to demonstrate the NVRO Clean Leach Process at scale .
The plant includes : multiple cascading mixed acid leach tanks , a counter current decantation ( CCD ) system , residue neutralisation and
JUNE 2024 | International Mining 29