HIGH PROFILE
“ In no way are we competing with vendors – we are not suggesting we have the expertise they have ,” Adrian Dance says . “ Rather , we are looking at the characteristics and amenability elements for the vendors to then truly apply their expertise , knowledge and sensor selection understanding ”
McCarthy added : “ We firmly believe that this fivestep evaluation will allow people to sign off , at least at a PFS level , on whether pre-concentration is a viable route for them to take . Our process will prove this through testing and pulling different economic levers in the economic evaluation to quickly see where the value is , and where it isn ’ t .
“ If pre-concentration is viable , you would then likely see clients moving on to performance testing with some of the sensing / sorting vendors at the feasibility study stage .”
Welcoming the independence
Those who understand the pre-concentration space have welcomed the involvement of SRK through its five-step process and , in particular , have highlighted the industry need for standardised and independent testing .
“ They see where we are inserting ourselves into stages of the client and vendor relationship ,” Dance said . “ In no way are we competing with vendors – we are not suggesting we have the expertise they have . Rather , we are looking at the characteristics and amenability elements for the vendors to then truly apply their expertise , knowledge and sensor selection understanding .”
At the same time , Dance and McCarthy are looking to arm mining companies with relevant knowledge about pre-concentration principles , where the process could provide a grade uplift and what losses might be associated with the implementation . This is being done through gaining a better understand of their orebody through the testing .
It should result in mining companies providing a more representative sample to the pre-concentration vendors for the performance testing many of them offer . “ Mining companies can then understand these pilot test results more broadly and ask more questions , if needed ,” Dance said . At the same time , the vendors have a ‘ pre-qualification ’ check in hand : they would know from the SRK process if there is a strong basis for carrying out the performance test in the first place .
And , of course , SRK can get involved after the five steps are complete , carrying out small-scale work and integrating these results with the larger scale performance testing that could eventually underpin a flowsheet developed by a third-party engineering company .
“ We view pre-concentration as another aspect of geometallurgy that needs to be interrogated just like comminution and flotation ,” Dance said .
The future focus
It is potential changes to both of those processes that could have positive implications for pre-concentration in the mining sector .
“ We ’ re now seeing more flowsheets designed with a multi-stage comminution flowsheet that , at every stage , asks : ‘ do I need to process the oversize material again ?’” Dance said . “ There is an opportunity for the right sensors to answer those questions . That is being highlighted in the design of
“ We firmly believe that this five-step evaluation will allow people to sign off , at least at a PFS level , on whether pre-concentration is a viable route for them to take ,” Bob McCarthy says
some of this technology ; some newer ore sorting units are reminiscent of cone crushers in size and shape , which means they can be inserted into this flowsheet with ease .”
And , of course , some pre-concentration-focused companies have gone upstream of the plant to the pit to provide these readings : an area Dance sees as representing the future .
“ Heterogeneity is better preserved the further upstream of the plant you go , so it is obvious to think that pre-concentration technology – which feeds off this heterogeneity – should be placed here ,” he said . “ The issue comes with getting a representative sample to test – whether that is a shovel load , or the equivalent of what a 200-t payload truck can carry . Ultimately the mining industry is at a ‘ prove it ’ stage when it comes to pre-concentration technology . The mining companies want to see results on paper or on a screen before they sign off on this technology and process . At the scale of a truck or shovel , this is very challenging .”
McCarthy added : “ The Heterogeneity and Scale analysis we are doing in step one of the evaluation will identify some of these opportunities within the selective mining unit sizing , but it is still early days on factoring that into sorting at a truck or bucket scale .”
This work will require closer examination of the drill core than the typical 1- m assayed intervals , as well as a way to estimate the level of mixing that occurs between vertical blast holes , post-blasting , post-loading and postconveying .
This comprehensive plan is broadening too , factoring in more than just economics .
For instance , SRK has made a case for carrying out the same sizing and XRT analysis included in the five-step evaluation for mill pebbles – which can represent up to 30 % of the entire plant feed in some cases – to assess their true value .
This obviously has a cost benefit , as well as an energy benefit – avoiding recirculation of pebbles avoids excess energy use . This same testing is indicating there could be further energy benefits to be had by using preconcentration , too .
In addition , “ We have recently expanded our testing protocol to now measure specific energy requirements of the concentrated material compared with the original feed ,” Dance said . “ This has shown ( at times ) a softening effect of pre-concentration that can produce measurable savings in power .”
And the impacts on water and energy use are another avenue that could come into the ‘ size the prize ’ economics McCarthy uses in step two of the fivestep evaluation process . “ There is no reason to think this could not be included in the analysis in the future ; all we would need are the metrics for the existing proposed operation – the amount of water and energy used for the number of tonnes in the mill feed ,” he said . “ It will then just be a simple case of amending the two inputs based on the pre-concentration work .”
Against a backdrop of falling grades , increasing metallurgical complexity and perceived future demand for commodities , the pre-concentration question needs to be asked by all companies . IM
MARCH 2024 | International Mining 11