AUSTRALIAN METS
Capital Limited and MSALABS service expansion program at Barrick Gold ’ s Bulyanhulu gold mine in Tanzania .
Wess Edgar , Chief Geologist for Kirkland Lake Gold in Australia , recently said of the technology : “ We believe the PhotonAssay method has potential benefits for our business that include simple sample preparation , fast turnaround times for high-quality results , and improved outcomes related to health , environment and the community .”
The recent upheaval in the assay market has led to even more companies adopting Chrysos ’ technology , according to Treasure .
“ We have hit the holy grail in the industry as lab fire assay turnaround times are back up to 10- 12 weeks ,” he said . “ Companies are now no longer at the point of testing our method and the old method side by side for comparison . You either wait 12 weeks for conventional analysis , or , for a faster turnaround time at a similar price point , you choose our proven technology .”
Just one of the areas where the technology ’ s cost , efficiency , accuracy , speed and environmental benefits have been shown is in the coarse gold sector .
Dr James Tickner , Chief Technology Officer of Chrysos and PhotonAssay inventor , explained : “ Traditional analysis techniques such as fire assay measure a small sample , typically only 30- 50 g . To obtain a reasonably representative sample , the ore material is first crushed and then pulverised to a fine powder .”
After pulverisation , sampling errors for coarse gold ores can be significant , particularly where the gold is present as larger metal nuggets that do not break down easily during grinding , according to Dr Tickner .
He referenced one study on samples from a Western Australian deposit that showed errors on fire assay exceeding 60 % ( one standard deviation ) and gold measurement errors across the operation in the range of 30-40 % ( one standard deviation ).
“ Apart from the time and effort involved in pulverising , the soft and malleable nature of gold introduces other problems ,” Dr Tickner said . “ Gold can ‘ plate ’ onto the grinding equipment , leading to an apparent loss of gold from the samples being measured . Gold can also carry over from one sample to the next , leading to cross-sample contamination unless equipment is carefully cleaned between samples .” PhotonAssay avoids these problems . First , lab technicians do not need to pulverise the ore – alleviating the ‘ plating ’ issue that comes with fire assay . As Dr Tickner says , the technology inherently “ counts ” gold atoms , irrespective of the chemical or physical form of the sample .
Second , the sampling process considers up to 500 g of sample , rather than the 30-50 g offered by fire assay . For particularly challenging materials , it is practical to measure large samples in their entirety by portioning them into several PhotonAssay jars , with a recent study demonstrating the use of PhotonAssay to measure complete 5 kg samples of extremely coarse gold ore .
Both factors help improve the ‘ representativeness ’ of the assay in coarse gold operations , as has been seen at Fosterville and Novo Resources ’ Beaton ’ s Creek project ( Western Australia ).
Improvements in assay confidence permeate through the whole resource / reserve definition and mining process , according to Treasure .
“ Rather than just the analysis comparison of a fire assay and PhotonAssay , we look at what the use of this technology actually means for your entire ore structure ,” Treasure said . “ It ’ s easily forgotten that a lot of analysis in the industry comes from infill drilling , often on 25 m spacing from 2-4 in ( 51-102 mm ) core or rock chip drilling .
“ You are trying to garner information about the orebody based on what is already a small subset of information .”
Miners then take a subset of that sub-sample to build a mine plan , introducing further errors and assumptions into the calculation .
“ We , at Chrysos , are looking at the bigger picture by taking the results of our improved analysis technique and reconciling it back to the larger dataset at mine sites to improve the outcomes of mining and processing .”
As Dr Tickner says , improved assay precision translates into better resource definition , grade control and mill reconciliation .
Collaborative blasting expertise
Orica , as has been shown with its work on BLAST DOG , is collaborating across the Australia METS ecosystem to , it says , cultivate and deliver innovative technologies to raise the mining industry ’ s productivity .
A second , but related collaboration to BLAST DOG is with DataCloud to further enhance the
Orica says digitally-enabled blasting unlocks productivity by connecting blast inputs to outcomes
capabilities of the company ’ s revolutionary RHINO™ Seismic While Drilling system .
“ This real-time subsurface measurement technology provides high-resolution rock mass data through vibration measurement on IoT sensors enabling accurate detection of faults , fractures and joint spacing in addition to many grade indicators and blast-critical measurements ,” Orica explained .
The company has since gone onto acquire the RHINO technology and is in the process of integrating it into its digital blasting solutions portfolio .
The blasting company is also taking on the role of commercialisation partner for the Integrated Extraction Simulator ( IES ), developed by Brisbane-based Cooperative Research Centre for Optimising Resource Extraction ( CRC ORE ).
Representing the next generation of mineral processing simulation , IES is a cloud-based software platform designed to reduce the use of energy and water in mining through the application of simulation , optimisation and machine learning , Orica says .
Another example of Orica ’ s industry ’ s collaboration comes in its Design for Outcome collaboration with Roy Hill in the Pilbara of Western Australia .
Centred around Orica ’ s BlastIQ™ digital solutions , which is designed to improve blasting outcomes by integrating insights from digitally connected technologies at every stage of the drill and blast process , Design for Outcome is an automated continual optimisation solution that sets a new benchmark for blast loading designs , according to Orica . It leverages data science to process both upstream and downstream data to automate blast designs , producing tailored and optimised designs that reduce blast variability and explosive consumption while increasing productivity .
20 International Mining | MAY 2021