SAMPLING , ANALYSIS AND LAB ASSAY your ore , which reduces the crushing and grinding costs and provides a better delineation between ore and waste ,” he said .
In the process plant , meanwhile , IMA has sought to ‘ clean up ’ the slurry sampling process by employing its IMACON On-Stream XRF Analysers .
Auranen explains the rationale for entering this part of the market : “ The problem with the current status quo in slurry analysis is not the analysers themselves , but the sample being taken . One slurry analyser typically takes samples from several points in the process ; it could be 15 sources in some instances . At the same time , you typically take the sample from a long distance away , with the sample delivered to the analysis point through lots of piping .”
He added : “ As this process continues , the representativeness of the sample gets worse and you also tend to encounter problems with the piping and slurry flow .”
Auranen recommends more analysers and less piping to improve both the accuracy of the process and the cost associated with taking such samples ( the latter considering the required maintenance and piping infrastructure for the slurry handling ).
Asked how he sees the whole analysis , sampling and lab assay market evolving , Auranen said wider recognition of the benefits that come with increasing the accuracy of these processes could end up changing the dynamics .
“ The main purpose in the future for lab analysis will be to provide quality assurance and quality control for online analysers in the field / on site – calibrating and monitoring the performance ,” he said . “ Lab equipment will not so much be used for carrying out the analysis work on physical samples , they will be used to verify the validity of the results from online analysers .” The reason for this ? “ Often with lab results , you cannot react ,” he said . “ You can only see what went wrong after the fact . With the online system , you can react to any problems that you see in real time .
“ This will eventually help for bulk ore sorting and preconcentration methods , in addition to the move towards future trends like autonomous mining .”
Lab process automation
Two technology companies focused on the laboratory have recently pooled their expertise to help automate one of the more labour intensive and risky elements of mineral sampling .
The combination of ColdBlock Technologies ’ Digestion 3rd Generation Product Line and Nucomat ’ s Compact Sample Preparation Unit will enable an automated process of “ raw sample in , analysis-ready sample out at unprecedented speed and level of
operator safety ” for labs dealing with mineral samples , according to Nick Kuryluk , CEO of ColdBlock .
Since unveiling ColdBlock Digestion back in 2015 at the annual PDAC Convention , the company has focused on developing a “ solid evidence generation package ” that validated the performance of the technology in both the academic setting and the realworld setting through mining organisations and commercial laboratories , Kuryluk says .
The performance parameters that were validated included a high return on investment , elevated workplace safety , and high analytical accuracy and precision , he claimed .
ColdBlock ’ s participation in the Amira Global P1196 project , which has SGS , Freeport McMoRan , New Gold , Centerra Gold and Newcrest as participants , was instrumental in this validation process .
The project enabled ColdBlock to demonstrate that its sample digestion technology – which uses shortwave infrared radiation to primarily energise sample particles , rapidly dissolving solid matter into a solution for instrumental multi-element analysis – delivers similar analytical measurements to fire assay for gold determination and similar analytical measurements to hotblock for base metal determination .
“ However , it was further validated that the ColdBlock process can be performed in minutes compared to hours and the cost savings were substantial ( average of 50 % cost savings vs fire assay for gold application ),” Kuryluk said .
In regard to workplace safety , its digestion technology has eliminated the use of lead for gold determination ( commonly used in fire assay ) and , thus , removed potential lead contamination for workers and lead waste , he added . “ For base metal applications , we reduced the use of hydrofluoric acid and perchloric acid in the digestion process , both of which are harmful reagents .”
Kuryluk says the speed of ColdBlock ’ s digestion system is unmatched compared with conventional methods .
“ We can digest sample materials for gold analysis in minutes compared to hours with fire assay ,” he said . “ We can also digest sample materials for base metal analysis in minutes compared to hours with hotblock .”
The tie-up with Nucomat , a company that provides lab automation solutions for sample preparation , handling and testing in quality control laboratories , will provide an automated system capable of rapid acid dispensing and digestion , according to Kurlyluk .
The integrated product line will first be offered through the Amira Global Project P1196A initiative , Kuryluk explained . This will be delivered in the June quarter of 2021 , with the commercial product available globally in the September quarter .
Kuryluk concluded : “ The end goal of the collaboration is to deliver a powerful solution to today ’ s challenges of sample preparation and to meet the current needs of the laboratory environment .”
PhotonAssay ’ s watershed moments
Chrysos Corp is also looking to replace the traditional gold analysis method of fire assay , a task the company is well on its way to achieving with its
PhotonAssay technology , according to CEO Dirk Treasure .
Since acquiring the novel X-ray technology – based on Gamma Activation Analysis – from Australia ’ s CSIRO in December 2016 , the company has made significant progress in gaining industry traction .
“ We picked up the technology from CSIRO in what was a late-stage concept ; the science had been proven but it hadn ’ t been commercially packaged ,” Treasure explained to IM .
With a commercial model now fully established , the benefits CSIRO stressed more than four years ago are becoming apparent to the wider industry .
PhotonAssay causes excitation of atomic nuclei , allowing enhanced analysis of gold , silver and some complementary elements . The process slashes the time it takes to analyse a drilling sample from days to hours and provides a chemical-free approach to material analysis that delivers accurate results and uses a larger sample size ( up to 500 g ), with reduced sample preparation than fire assay , according to Chrysos .
Further selling points include the ability to test samples repeatedly if required – unlike fire assay , which involves the destruction of the sample – and the generation of no contaminated waste or disposal and associated costs .
All these qualities have been strengthened since Chrysos got its hands on the technology .
“ We have had a team of development scientists improving the tech itself and broadening its application , both within gold and other elements ,” Treasure said .
“ The other thing these scientists have developed , specifically within gold , is an improvement in detection limit . We started off with a 30-40 ppb ( 0.04 g / t ) detection limit and we have now improved that down to 0.008 g / t .
“ That is a pretty significant improvement in detection limit , which then leads to improvements in precision and accuracy .”
Such precision and accuracy can translate to more recoverable gold and higher revenues for miners .
One company to recognise this is Kirkland Lake Gold , which recently received a PhotonAssay unit at its Fosterville gold mine , in Victoria , Australia . The two signed a pact in the September quarter of 2020 and Treasure said the unit , being operated by Bendigobased On Site Laboratory Services , is now up and running .
“ What we are doing at the moment is evaluating the workflow to effectively manage the samples as they come in from the site in order to quickly get the analysis data back to the people that need it ,” Treasure said of the unit at Fosterville . “ We ’ re working out : if a process sample comes in at 6 am , how quickly can we get that analysed and emailed back to the metallurgy team so they can use it for their process control ?” Some of the more recent work at Fosterville includes test work on moisture analysis for process plant operators – a procedure that shows off another of PhotonAssay ’ s credentials .
FEBRUARY 2021 | International Mining 63