SAMPLING , ANALYSIS AND LAB ASSAY
The IMA Blasthole Sampler Analyzer , or PDSA , whether in the ScanVan setup deployed at Boliden ’ s Kevitsa mine ( left ) or on-board drill rigs ( right ), collects samples and dense drill cutting data from production and reverse circulation holes in real time to create accurate 3D mine maps of blast benches took less than five days to pay back the investment .
While the mine in question ended up installing a representative sampling station to measure the copper grade , not all mines select such a solution – a fact often revealed during site surveys , Knudsen says . “ This may be caused by sampler manufacturers not understanding the principles of correct sampling , providing poorly designed or inferior quality equipment , or even the incorrect selection and implementation of sampling equipment at the design stage , leading to compromised sample quality ,” she explained . “ Decisions made on compromised sampling can account for quite a lot of lost or unrealised value .”
Even if the equipment is correctly selected , some mines still insist on carrying out manual sampling despite the obvious health and safety issues associated with it , Knudsen said . “ At the same time , there is a higher likelihood of collecting a biased sample with the wrong frequency with this manual process ,” she added .
This is where FLSmidth can use its end-to-end quality chain expertise – some of which came with the acquisition of IMP Automation in 2019 – to transform the on-site mine sampling sector .
In more than 30 years , the company says it has designed and delivered automated laboratories to the mining sector , and now holds the largest number of installations worldwide within many different commodities .
FLSmidth uses this experience , plus an extensive back catalogue of mineral processing plant designs , to create a quality chain from sampling to analysis that increases the overall accuracy and provides miners with optimised processes that generate real value , according to Knudsen .
She concluded : “ Because we have this broad experience , it means we can be the partner of choice for those customers who want to have a holistic view of their quality chain .”
Changing roles
IMA Engineering , like FLSmidth , takes a universal view of sampling and analysis within mining . The company has been using online analysis tools to improve mining operations for many years , from the field to the plant .
IMA was one of the earliest companies to integrate XRF technology into the drill core analysis process , according to Chairman Ilpo Auranen , with IMA partner MOLS producing the Nordic region ’ s first mobile core scanner prototype more than 10 years ago .
“ We have probably analysed more core via XRF than anyone else ,” Auranen told IM .
The Finland-based company has leveraged this experience to refine the drill core analysis process by providing “ denser ” readings that truly reflect the mineralisation across the entire sample and allow companies to prioritise exploration time and investment .
IMA has now got to the point where it is using this online drill core analysis process as an input for ore sorting studies , providing visibility on the future mineral processing flowsheet while exploration rigs are potentially still on site .
Going further downstream of exploration , IMA ’ s XRF expertise is also being sought within the open pit .
The IMA Blasthole Sampler Analyzer , or PDSA , collects samples and dense drill cutting data from production and reverse circulation holes in real time to create accurate 3D mine maps of blast benches .
This information can be used to verify the mineral grade throughout the drilled hole and amend blasting processes .
Auranen explains : “ We have tested the PDSA on
many sites and carried out lots of research , noticing the same phenomenon – the ore is much more heterogeneous than mining companies think .”
The company proved this in a demonstration as part of the European H2020-backed ITERAMS project .
The demonstration took place at Boliden ’ s Kevitsa mine , in Finland , with IMA using a PDSA system integrated into a transit van ( the ScanVan ). Pouring samples into a hopper from a bucket , the ScanVan device was able to ascertain that the ore grade varied significantly in not only each blast hole , but within the upper , middle and lower samples of the blasthole cuttings analysed .
Blasthole sampling is nothing new for the industry , but IMA ’ s process is different .
“ Typically , in the blasthole sampling process , you take one sample per blasthole ,” Auranen said . “ One sample gets to the lab and the size of the sample tested tends to be around 50 g , which is supposed to represent 3,000-5,000 t of material within the pit .
“ This process comes with two issues . One , the grade varies as a function of the hole depth and , two , the amount of cuttings coming out of the hole varies , with the ore unevenly distributed within the cuttings .”
A very deliberate shoveling action that samples cuttings from the top , middle and bottom of the cutting pile – similar to the test at Kevitsa – would be needed to obtain a result close to ‘ representative ’, but the only way to obtain full accuracy is continually analysing what comes out of the hole in real time , according to Auranen .
This is what the company is currently working on , with the PDSA system ready to be integrated on any manufacturer ’ s drill rig within a matter of months , Auranen said .
IMA says of such a system : “ The PDSA provides Analyse While Drilling and Measure While Drilling data to provide accurate elemental analysis and rock / ore hardness information , combined with ore and waste rock location coordinates .”
By accurately and autonomously identifying this information , the subsequent blasting process can be adapted , Auranen says . More explosives can be loaded into the hole section where the ore grade is higher and less where waste has been detected .
“ This allows you to get better fragmentation of
62 International Mining | FEBRUARY 2021