HIGH PROFILE
Pre-concentration : it ’ s worth asking the question
We ’ ve reviewed a novel , vendor-agnostic pre-concentration screening test in part one and explained a comprehensive five-step pre-concentration evaluation in part two … now for part three in the three-part series with SRK Consulting ( Canada ) Inc ’ s Adrian Dance ( Principal Metallurgist ) and Bob McCarthy ( Principal Consultant )
SRK Consulting ’ s Adrian Dance and Bob McCarthy have devoted years to ensuring the mining industry can make informed decisions about preconcentration within their flowsheets and are now able to screen the opportunities quickly , cost-effectively and without vendor prejudice .
“ We have been carrying out the different parts of the five-step evaluation process over the years , refining them independently and sometimes together ,” McCarthy tells IM . “ It is only now that we can present them all in a holistic way .”
This five-step process – which includes heterogeneity analyses ; “ size the prize ” economics ; laboratory test work that involves X-ray Transmission ( XRT ) based sensor technology ; mine planning ; and mine economics – has been deliberately designed to allow mining companies to pause at the end of each phase to re-evaluate if there is a strong enough case to continue with a preconcentration investigation .
The importance of such an approach has grown in recent years as more projects that are “ grade-challenged ” or metallurgically complex are being considered for exploitation by mining companies as the demand for metal increases worldwide .
Sensing this ( pun intended ), sorting and sensing manufacturers have been on the mining charm offensive , proclaiming the benefits of their technology – benefits that include cost reductions , improved metallurgical recoveries , rationalised use of energy and water , and more .
These market dynamics have created a void that SRK is looking to fill by providing the tools for both sides to assess the options and carry out informed decision making on which routes to pursue .
“ We were concerned that the manufacturers didn ’ t have the background needed to understand the mining industry ’ s requirements ,” Dance said . “ At the same time , mining companies had difficult projects and deposits where they saw pre-concentration potential but didn ’ t know where to initially go to explore that potential .
“ We saw a space for industry representatives like ourselves at SRK to bridge that divide .”
The independent testing that SRK has been able to offer for the last six or so months through its partnership with Base Metallurgical Labs ( BML ) in British Columbia was the final piece of the puzzle in establishing this nowestablished five-step process .
Able to not only indicate preconcentration amenability but also provide key inputs into the pre-concentration strategy selection and evaluation , this has been employed for some 36 samples ( close to 2,000 particles ) being tested using the XRT unit situated in BML ’ s facility in Western Canada .
Demystifying the tech
While this XRT testing may have only recently become available to SRK and BML customers , the outcomes of SRK ’ s pre-concentration evaluation have been described to investors and stakeholders trawling through NI 43-101 reports up to the prefeasibility study ( PFS ) level for some time now . Various parts of the five-step evaluation have come into sections on metallurgical test work , mineral reserves , mining methods , costs and economics .
“ Where the results feature is tied to what study stage the company is at and where people feel comfortable with pre-concentration ,” McCarthy explains .
Providing comfort to mining companies and their investors is always difficult when examining any new flowsheet addition , hence the reason why many companies are initially pursuing pre-concentration or ore sorting in a ‘ recovering ore out of waste ’ scenario from material already deemed to be waste and having no economic value . As a result , SRK has been very deliberate in the protocols it is pursuing . Dance explains : “ Because there is still a perceived ‘ magical ’ nature to preconcentration in that it can provide reserve upgrades and higher recoveries , we need to do more detailed evaluations at a preliminary economic assessment or PFS level than would be expected for other types of processing technology .”
For instance , the company is currently engaged on a gold operation where it has tested upwards of 22 samples ( 1,320 particles ) for validation . “ At this level of study , if you were working on comminution or leaching , the same process validation would be carried out with two or three tests ,” Dance said .
Various parts of SRK ’ s five-step evaluation are referenced throughout sections of 43-101 reports on metallurgical test work , mineral reserves , mining methods , costs and economics
10 International Mining | MARCH 2024