Tag Archives: ore sorting

Serabi Gold looks to repeat ore sorting success with COMEX system at Coringa

Comminution of minerals, Environmental, Mineral processing, Mineral project development, Mining equipment, Precious metals, , , , ,

Serabi Gold is planning for the start-up a second sensor-based sorting solution from COMEX as it looks to commence operations at its Coringa project, in Brazil.

The company confirmed in its June quarter results that construction of the classification plant was well underway at Coringa, with the crusher expected to be operational in August and the ore sorter remaining on track to being operational by the start of the December quarter.

A spokesperson for Serabi explained that the ore sorter being used is a COMEX OCXR-1000 model. This sorting unit is manufactured to sort a feed fraction +15 mm/-45 mm, with a maximum volume of 30-40 t/h. The stated maximum rejection rate is approximately 35% and it operates at a maximum belt speed of 2.7 m/s.

The COMEX OCXR-1000 is equipped for both X-ray sorting and colour sorting, with the latter using a 4K RGB camera. The whole unit at Coringa is within a single 13,500 x 3,500 x 2,900 mm (length/width/height) size envelope.

In a June corporate presentation, Serabi Gold said it is using ore sorters to remove waste and pre-concentrate run of mine material, as well as to liberate plant capacity. It noted the Coringa ore was highly amenable to ore sorting, with the company having carried out geological and metallurgical reviews and “pre-tested” its use at its Palito Complex, some 200 km from Coringa.

Since 2020, Palito has fed 40,891 t of material at 1.7 g/t Au through the same ore sorting system. This has generated 4,899 t of product at 8.8 g/t Au, with 35,992 t at 0.7 g/t Au rejected.

Coringa is viewed as a low-risk, low-cost operation, being a “carbon copy” of Palito, according to Serabi Gold. Palito was set to produce 38,000-40,000 oz of gold in 2024 from an operation made up of an underground selective open stoping mine, a 600 t/d conventional flotation, carbon-in-pulp, ore sorting operation. Coringa, meanwhile, is set to use a classification plant made up of a crusher and ore sorter to produce 38,000 oz/y of gold through an integrated flowsheet still in development.

QKR Navachab gold mine orders new STEINERT ore sorters

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QKR’s Navachab gold mine in Namibia has ordered two new KSS ore sorters from STEINERT, upgrading from a mono- to multi-sensor sorting solution in the process.

The two new units will replace and upgrade STEINERT XSS-T X-sorting systems after seven years running time, STEINERT says.

The option for a multi-sensor has proven to improve process results with an important increase in gold recovery, according to the company. It added that the applicability of dry sensor-based sorting technology has proven over the years of production with great enhances on ESG aspects, especially on water savings.

Back in 2021, STEINERT set up a new testing plant at Navachab, with the test facility available for testing in beneficiation and pre-concentration processes.

HPY provides ‘transformational’ ore sorting upgrade at Fankou lead-zinc operation

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HPY prides itself on being “the manufacturer of the world’s most diverse and efficient ore sorting product line” and, it says, this has been proven in the newest technical upgrades carried out on Shenzhen Zhongjin Lingnan Nonfemet’s Fankou Mineral Processing Plant and Construction Material Plant, in China.

Through the strategic use of all new models of HPY’s sensor-based sorting machines, Fankou’s Mineral Processing Plant has experienced a transformation in the sorting system, the company says. The mine can now sort coarse particle sized ores using HPY’s Golden Coal Series, elevating efficiency in the SAG mill, reducing the energy consumption of the whole system and significantly reducing the size of the mine’s tailings pond.

Previously, Fankou had registered a $2.9 million annual revenue increase following the introduction of four HPY Classic Series sorters. Currently, one Circle Series XRT sorter has the same sorting capacity as two conveyor belt-based sorting machines; the most recent technical upgrade allowed Fankou to replace four Classic Series sorters with two Circle Series sorters, reducing electricity usage by 14 times. These figures demonstrate the significant financial benefits that can be achieved using HPY technology, HPY says

In the article, “Maximising the benefits of sensor-based ore sorting machines,” published in April 2023, HPY Technology outlined how the cooperation project came together.

Fankou’s two process plants, the Mineral Processing Plant and the Construction Material Plant, are in Renhua County, Guangdong, China, and have a long history. Once one of Asia’s largest lead-zinc mines, this mine faced significant challenges as the years progressed. As Mr Luo, the plant’s General Manager, explains, “In its peak year, it could deliver approximately 180,000 tons of lead-zinc. However, after over 60 years of production, depleting resources and accumulating waste rock piles forced the mine to take drastic measures to modify the entire processing chain.” Such conditions underscored the necessity for solutions like HPY’s machines.

Fankou’s entire modification plan was ambitious; its total budget was estimated at $27.6 million since it needed to lay the groundwork and renovate the building, adding HPY’s ore sorting step to the process flow fitted nicely within its plan of upgrading its overall mining process.

At the end of 2017, Fankou’s executive team went to HPY Technology’s testing centre to carry out preliminary sorting tests. Mr Luo noted: “There were few companies in China that did sensor-based sorting at the time; in addition, Fankou’s lead-zinc was considered by many the ‘hard-to-sort’ type.”

Not long after, HPY and Fankou’s team decided to approach this project as a research project in 2018, the two parties agreed HPY would form a dedicated team to conduct specialised research on providing the most economical and technically responsible lead-zinc sorting solutions for the Fankou project. It did not take long for satisfactory results to start coming in. HPY successfully fulfilled its mission in 2019, and the machines were officially added to the plant thereafter.

Fankou’s mineral processing plant initially used four Classic Series P60-X1400 ore sorting machines. The machine processes the particle size range of +10-90 mm, which accounts for about 50% of the raw ore. This accounts for 2,600 tons of ore, rejecting 400-500 t/d of waste rock. After pre-concentration, the lead and zinc content in the waste rock is below 0.3%, and the sulphur and iron content is below 3.8%. Therefore, the ore sorting process enriches the ore grade by 1.08% for lead and zinc and 2% for sulphur and iron.

Figure 1: Four Classic Series P60-X1400 ore sorters in Fankou’s mineral processing plant

This sorter is the typical conveyor belt metal separator in China, and similar designs are seen elsewhere.

The project highlighted how HPY’s boosted machinery throughput had positively impacted the safety aspect of the mine’s mining practice; the mine can now mine more areas by vertical blasting, eliminating the risk of personnel working underground entirely, it says.

Mr Luo commends HPY’s updated ore sorting machine for completely changing the way Fankou mines: “Due to the depletion of mineral resources and the Chinese government’s increasing emphasis on the ESG aspect of the big mines, we did underground mining before discovering the option of HPY sensor-based sorting. However, not only is the production rate not ideal, but because the space in the underground channels is very narrow, we need personnel to attend to the errands, which makes the mining production very low and extremely unsafe.” He added: “After vertical crater retreat and large blasting, a large number of tailings and the unnecessarily high cost generated in the mills during the processing can be significantly reduced with an ore sorter; all we need to do is send in carts, have it shoveled onto the bin, and have it crushed, screened and cabled to the sorters.”

Since its installation, HPY Technology has upgraded its entire product line. With an enhanced sensor detection system and a remodelled module design that allows for easy maintenance, HPY’s machines’ processing capacity significantly improves compared with the older models. By March 2023, after using HPY’s machines for four years, Fankou – now a ‘royal customer’ – was open and excited for another round of machine upgrading to increase the amount of sorted material.

Upon HPY’s advice, the Fankou Mineral Processing Plant switched its four Classic Series to two Circle Series and one Golden Coal Series (See Figure 2). The Golden Coal Series was previously made to sort coal; after some updates and redesign by the HPY R&D team, it is now made specially for large particle-sized ore sorting. In Fankou’s case, +40 mm-90 mm sized ores will enter the Golden Coal Series for pre-concentration. As for the two Circle Series on the side, their expertise lies in their accuracy in sorting and large processing capacity that could replace two typical conveyor belt-based sorters with one machine. Their particle size ranges from +10-40 mm, considering those are the major distribution sizes produced during the initial screening process in Fankou. However, according to Mr Luo, Fankou is still in the process of optimisation now that the upgraded machines could process greater size distributions: “In the past, ores that are larger than 90 mm will enter straight into the SAG mill process, we plan to increase the Circle Series particle size to +10-60 mm and feed the +60-150 mm to the Golden Coal Series, this will help us increase the efficiency of the semi-autogenous mill process even more.”

Figure 2: Left being the Golden Coal Series, the middle and the side ring-shaped machine being the Circle Series

The ore sorting process modification consists of first removing one Classic Series and replacing it with a Golden Coal Series. The installation and training process took one month, and, by June 2023, the Golden Coal Series was running at total capacity. The two Circle Series’ implementation stretched longer as the mine could only halt its production for installation during more extended holidays in October 2023 and February 2024. Therefore, it took the entire Fankou Mineral Processing Plant a year to update all of the ore sorting machines (see Figure 3).

As mentioned before, the processing capacity prior to the update was around 2,500-2,600 t/d; after the machine update was completed, it went up to 3,500 t/d. A benefit of this update is that the Circle Series has less power consumption; thus, more revenue is generated from the sorted ore. The circular vibrating material layout maximises the symmetrical mass of the disc, requiring minimal excitation force to drive the ore toward the circumferential direction evenly. This significantly reduces energy consumption compared with traditional feeders, which rely on excitation force to move under their own weight, HPY says. Compared with belt-type ore sorting equipment with a width of 1.4 m, the energy consumption of this 1.5-m diameter disc feeder machine can be reduced from 7.5 kW to 0.75 kW.

HPY Technology | Fankou lead-zinc Mine, Mineral Processing Plant
Machine used One Golden Coal Series | Two Circle Series
Processing capacity 3,500 t/d
Particle size +10-150 mm
Concentrated ore grade (Pb+Zn) 12% (most economic ore grade)
Waste rock grade (Pb+Zn) <0.3%
Grinding grade (Pb+Zn) increased by 1.08%
Rejection rate 16-17%
Figure 3: Before and After with the HPY machine update in Fankou

The Chinese government has ordered Fankou to close its tailings pond by 2025. Thanks to the support of HPY Technology Golden Coal Series coarse particle sorters, Fankou is able to effectively decrease its tailings pond and have 58% leftover tailings for backfill, it says. In the close circuit of the Fankou Mineral Processing Plant, every resource is used and no ore has gone to waste.

“At HPY, we are focused on exploring paths that may revolutionise the mining of natural resources and pushing forward sustainable extraction through our expertise in resource management,” Coral Lin, Manager of HPY Branding Department, says.

Pre-concentration: it’s worth asking the question

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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.

BobMcCarthy-SRK
Bob McCarthy, Principal Consultant), SRK Consulting (Canada) Inc

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 pre-concentration 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.

McCarthy added: “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. 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.”

Adrian Dance, Principal Metallurgist, SRK Consulting (Canada) Inc

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 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 post-conveying.

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 five-step 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.

For more information on the XRT pre-concentration screening test SRK and Base Metallurgical Labs can provide, as well as the five-step evaluation process for pre-concentration amenability, click the link here

SRK’s stepwise approach to pre-concentration analysis

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Having outlined a new vendor-agnostic, lab-based “pre concentration screening test” for mining in part one of this three-part series, SRK is back for part two, discussing the wider pre-concentration evaluation process that this testing fits into

“With any pre-concentration analysis, we need to, first, understand the heterogeneity of the deposit; simply put, if you don’t have heterogeneity, you don’t have the ability to separate the good stuff from the bad stuff and carry out pre-concentration,” Bob McCarthy, Principal Consultant, SRK Consulting (Canada) Inc, says.

With this baseline in mind, SRK Consulting has devised a pathway for companies with drill core at their disposal to analyse whether pre-concentration is a viable option for their flowsheet.

Made up of five steps, this staged approach is deliberately designed to allow companies to pause at the end of each phase to re-evaluate if there is a strong enough case to continue investing the time and finances required.

The heterogeneity analysis is first up, which, under SRK’s evaluation, includes two different approaches based off drill hole analysis: Heterogeneity and Scale and Composite-Sample Relationship Analysis.

“Heterogeneity and Scale involves a process of looking up and down the bore hole at different aggregation distances from every sample and interrogating the sample grade – or net smelter return – against the aggregations above and below that individual sample,” he explains. “We then increase the size of the aggregation to see how that relationship changes.”

Such analysis enables SRK experts to derive the heterogeneity measures typically dubbed ‘waste in ore’ (mineralisation below the cutoff grade within an above cutoff grade zone) or ‘ore in waste’ (mineralisation above the cutoff grade within a waste or marginally below cutoff grade zone). Using a cutoff grade derived from industry benchmarking, the consultants assess the aggregation distance, as resolved in the vertical direction, with the “selective mining unit” (SMU), which typically relates to equipment sizing for mining.

“Heterogeneity and Scale involves a process of looking up and down the bore hole at different aggregation distances from every sample and interrogating the sample grade – or net smelter return – against the aggregations above and below that individual sample,” Bob McCarthy says

“The pitfall some companies go down is picking your SMU to match an equipment size and production rate typically aligned to a corporate or strategic objective,” McCarthy says. “This could mean generating a 12-14-year mine life for a gold operation, or some other investor-led metric that doesn’t necessarily respect the deposit’s heterogeneity.”

The second approach – Composite-Sample Relationship Analysis – allows consultants to further quantitatively assess those waste in ore/ore in waste heterogeneity measures.

“Those parameters have multiple uses after being determined,” McCarthy says. “For example, they help guide in the sample selection – you can even visualise them in 3D with something like Leapfrog. You can also see contiguous lengths of above or below cutoff grade material in ore zones or marginal waste zones, representing what an ore sorter may see. These would be targeted for testing.”

Responding to industry calls, SRK now offers a step between this fundamental heterogeneity analysis and the test work it can conduct at Base Metallurgical Labs’ Kamloops facility in British Columbia, with what McCarthy calls “size the prize” economics. It provides insight into possible pre-concentration strategy outcomes and, just as important, justification to continue to the next step of lab test work.

This process – carried out by SRK on several projects in the past – is designed to allow the mining company and consultant to test pre-concentration strategies from an economic perspective, assessing if an operation should be removing waste from ore or looking to recover above cut-off grade material from “marginal waste”.

McCarthy added: “It is about answering these questions: is it best to remove waste from mill feed, and to what maximum grade of feed, or to extract mineralised material from marginal, below cut-off grade material that increases the mineral reserve? And, of course, do the expected results of this process look promising?”

Gold is a good example here as the economic case study for pre-concentration often only stacks up when a “cap” is applied to the grade of ore subjected to pre-concentration. In other words, the highest-grade material should not be targeted. Even high-efficiency pre-concentration methods incur some metal loss, and any amount of “loss” that occurs in a gold project is difficult to make-up within a conventional flowsheet.

Example of drill core intervals showing waste in ore percentages of up to 80%

The third step in this five-step process is the lab test work McCarthy’s colleague, Adrian Dance (Principal Metallurgist at SRK Consulting), previously outlined in detail in the first article in this three-part series.

The “pre-concentration screening test” leveraging X-ray Transmission based sensor technology can not only indicate pre-concentration amenability, but also provide key inputs into the pre-concentration strategy selection and evaluation, Dance says. He says the testing offers an assessment of pre-concentration potential, as well as an estimate of material bypass and metal upgrade from samples as small as half cores.

Used in conjunction with crushing and screening, this testing rapidly – and cost effectively – assesses the potential for pre-concentration, which can then be applied to scoping or pre-feasibility studies, according to SRK and Base Metallurgical Labs.

Which is where steps four and five of the SRK evaluation – mine planning and mine economics – come in.

“With the heterogeneity measures assigning the distribution of waste in ore, ore in ore, and ore in marginal material in mining block models, the test results reflecting these conditions can be populated into those same models for mine planning,” McCarthy explains.

Typical mine planning steps of pit/stope optimisation, mine design and scheduling can proceed on the assumption of one or more pre concentration strategies, with different versions of mine schedules, reflecting different pre concentration strategies, evaluated.

This type of analysis typically works for a project in pre-feasibility study stage, where engineers can go into the existing block model, bringing the results from the heterogeneity and lab tests into the mine optimisation, design and scheduling process that takes place.

“The challenge is that the scheduling needs to assume a certain strategy – maybe you have determined what that strategy is close enough with the ‘size the prize’, but there are always a few elements you may want to tweak,” McCarthy says. “This could be the mass pull, or waste rejection targets, for instance.”

As a result, sensitivity analyses – mostly numerical tweaks – are embedded in the process.

When not dealing with a pre-feasibility-level project, the SRK team typically rely on an existing schedule that has been run during a scoping study or preliminary economic assessment. This model is modified and tested with different schedule scenarios and pre-concentration strategies based on the heterogeneity measures (step 1) integrated with the lab test results (step 3).

Out of the mine planning step comes a schedule that would go onto the next step: mine economics modelling.

“The model is configured to take in the heterogeneity measures, recovery curves, etc to change the amount of metal reporting to revenue and so forth,” McCarthy says. “Once I get schedules – based on the upgraded block models or it may be a pre-existing schedule – I would then put them into an economic model that has all the levers to pull for different pre-concentration strategies.”

Such a stepwise approach is indicative of where the mining industry is at the moment with vendor-agnostic pre-concentration analysis, enabling companies to get comfortable with the data and assessments as their understanding of their deposit’s heterogeneity grows.

There are potential refinements and fine-tuning opportunities too.

For example, if SRK was gifted with drill core or assay data that was more granular than the 1-2 m intervals typically taken at the exploration stage, it could indicate with greater certainty how particle sorting – typically analysing grades at intervals around a few centimetres – could benefit the deposit in question.

Also, if mine modelling software had matured to the point where block models could be tailored specifically to these waste-in-ore and ore-in-waste characteristics, SRK could segregate the areas in question, instead of applying the type of dilution factors they currently have in place to account for the grade-based realities. This would more clearly communicate the deposit’s heterogeneity to all stakeholders.

Yet, McCarthy and Dance know this will come in time, and are happy to work within the current confines to continue the industry’s education process and identify where the pre-concentration opportunities are

Further discussion on this and what SRK’s pre concentration analysis evaluation – with that embedded pre-concentration screening test – means within the broader mining industry context will follow in the final article in this three-part series later this year

STEINERT sensor-based sorting solutions helping Ferbasa adopt ESG practices in Brazil

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The use of sensor-based sorting (SBS) technology is allowing Companhia de Ferro Ligas da Bahia (Ferbasa) to avoid unnecessary processing by separating a fraction of the high-grade material from the metallurgical process feed in advance, a recent case study from STEINERT has revealed.

Ferbasa is in Ipueira, a municipality in the state of Bahia in the northeast of Brazil. It operates one of the largest chromite mines in Brazil and is considered a pioneer in the use of SBS technology, STEINERT says. The company processes chromite obtained from an underground mine, with the extracted material pre-concentrated using sorting technology that employs sensors, and is later used in the production of specialised steel alloys.

With a processing capacity of 12 Mt/y, the company has been using sensor-based sorting for 10 years, in a completely dry process that separates waste from high-grade chromite.

Eriberto Nascimento Leite, Mining Director at Ferbasa, says the ability to avoid unnecessary processing by separating a fraction of the high-grade material from the metallurgical process feed in advance through the use of SBS removes the requirement for any additional processing. In that way, particles which are not economically viable are eliminated from the process beforehand with only valuable material undergoing the follow-on concentration steps.

At Ferbasa, the use of SBS technology has enabled an increase in production, in addition to reducing costs in the subsequent processes, such as comminution and the use of inputs, such as reagents.

“Today, at Ferbasa, sensor-based sorting technology helps us adopt ESG practices, reducing waste, maximising production efficiency and contributing to the conservation of natural resources,” Nascimento says.

Nowadays, it is not only the mined ore that is processed, but also the stockpiles, which contain considerable amounts of chromium. The treatment of these stockpiles is only possible thanks to process automation and its high-capacity levels, which reach up to 180 t/h. Stockpile treatment has the potential to increase productivity in the mine. In terms of resource use, there is potential to reduce the consumption of water, energy and chemical reagents primarily because SBS is a dry separation process, unlike other pre-concentration processes such as dense media separation.

Ferbasa has always used a pre-concentration process with the aim of separating lump ore, which has a high chromite content, from the low-grade ore that goes to the concentration plant. However, this used to be a manual separation process. Bartolomeu Fonseca, the former Processing Manager at Ferbasa, discovered an article about sensor-based sorting technology from STEINERT. In 2012, he prepared material to be sent for tests at STEINERT’s Test and Development centre in Germany, and these were deemed successful.

A STEINERT KSS XT L in the chromite preconcentration setup

Ten years ago, when the first equipment was being installed, Ferbasa’s employees were sceptical about its capacity to support the adverse conditions in the mine. This is why STEINERT Latinoamericana, a subsidiary of STEINERT GmbH in Germany, offered a “try and buy agreement”. Over the years, the equipment’s high level of durability has been verified, resulting in the first unit still being in operation today, with a total of 34,000 hours of runtime.

“Looking back, it was not easy to apply the technology, but I decided to move forward because I believed that the technology could be effective,” Fonseca says. “Now, already retired, I am very proud of the legacy that I have left to the company. I had the full support from the mining director at that time, Wanderley Lins, but it was my responsibility to make it work.”

In 2014, during the commissioning of the first sorting system, a STEINERT XSS-T, STEINERT Latinoamericana started a partnership with Ferbasa.

Alonside this, STEINERT currently has a team of 30 collaborators who serve several mining clients in Latin America, in addition to having a test centre near the office in Brazil, enabling tests to be carried out with more convenience and efficiency for local clients.

Ferbasa started operating its first equipment in 2014. By 2019, it already had six units installed for the processing of run of mine and low-grade stockpiles.

The production benefits from flexibility of the sorting systems, which generate waste material, pre-enriched material and high-grade material. The processing capacities are up to 120 t/h for particles of 1- 3 in (25-76 mm), reaching up to 180 t/h for particles from 2-5 in. In terms of the sizes processed, the combination of sensors facilitates the separation of particles up to 5 in; a feature that, STEINERT says, reinforces the robustness and efficiency of the equipment for the detection and ejection of extremely coarse particles. In total, recoveries reach values of up to 90%, with upgrades of up to 1.5-3 times the feed levels.

Currently, Ferbasa applies SBS technology to process 100% of their run of mine, using two units from STEINERT, the STEINERT XSS T and STEINERT KSS | XT L, in a two-step process. In the first step, waste material is rejected, and, in the second, pre-enriched and high-grade materials are generated. The high grade-material meets the content specifications to be sent to the metallurgic plant, while the pre-enriched material is sent to another plant to follow other concentration procedures. Furthermore, the technology is applied in the processing of low-grade stockpiles, using two STEINERT KSS | XT L units – which combines the X-ray transmission sensor with three other additional sensor options (Induction, 3D laser, and Colour) – in two steps to separate waste, pre-enriched material and high-grade material. As a result, the low-grade stockpiles are processed in an economically viable way and with high sustainability gains.

SRK Consulting, Base Metallurgical Labs tackling pre-concentration amenability

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In this first of a three-part series of articles on pre-concentration in the mining space, SRK’s Adrian Dance outlines a new vendor-agnostic, lab-based testing process that could have huge ramifications for a sector in need of guidance and strategy.

Stay tuned for part two in the series, which will see SRK’s Bob McCarthy explain how results of such testing can be used by the mining community.

The need to expand the values or lives of assets while reducing both energy and water use is leading to a flood of new enquiries landing on the doorsteps of the pre-concentration and ore sorting company fraternity.

Anybody that takes a passing interest in the junior mining sector has seen the TOMRAs and Steinerts referenced in numerous TSX-V, ASX and AIM releases, with early-stage test work often detailing results from particle sorting trials.

On the bulk sorting side of the business, more sensor-based solutions are emerging to cope with the need to build or expand copper assets in the most sustainable ways possible. Some progressive companies are including such innovations in initial flowsheet plans.

The bottleneck in the current environment is testing, according to Adrian Dance, Principal Metallurgist at SRK Consulting, with many of the vendors simply overrun with requests to test material or provide modular pilot plants that can be re-located after samples are processed.

At the same time as demand is outpacing supply, there is an argument that a standardised, vendor-agnostic test should be devised to screen for ore sorting or pre-concentration amenability before any vendors are even engaged.

SRK is one company arguing for this.

“At the moment, the manufacturers are driving the action, dictating what the sample has to look like for something that resembles a pilot plant trial,” Dance told IM. “Like any pilot plant run, these trials often give you an excellent result on that specific sample, but the question is: is that sample truly representative of the orebody? Or, is it representative of what a sorter would actually see in operation?”

An increase in available data and transfer of said data across the mine site is going some way to disproving the idea of mass homogeneity at many bulk mining operations – at copper porphyries, for example.

Dance believes this same thought process should be applied to pre-concentration.

This is where SRK Vancouver and Base Metallurgical Labs, both in British Columbia Canada, are looking to provide a “pre-concentration screening test” using X-ray Transmission (XRT) based sensor technology that can not only indicate pre-concentration amenability, but also provides key inputs into the pre-concentration strategy selection and evaluation.

The two companies are offering an assessment of pre-concentration potential, as well as an estimate of material bypass and metal upgrade from samples as small as half cores.

The XRT sensor lab unit

Used in conjunction with crushing and screening, this testing rapidly – and cost effectively – assesses the potential for pre-concentration, which can then be applied to scoping or prefeasibility studies, according to the companies.

“The testing has two parts to it,” Dance explains. “It was originally designed to see what the grade distribution of fines is after crushing and to see how that grade distribution varies depending on the amount of crushing energy applied to the material.

“The second part is looking to see if the material is amenable to pre-concentration when it is coarse and dry – ie conveyable.”

According to the companies, the XRT-based test can provide this within 24 hours of a sample arriving at the lab.

All of this helps characterise deposits (or low-grade stockpiles) using small samples, cutting down sample mass requirements, and potentially running multiple scenarios to obtain what Dance refers to as the “optimal sort”.

The two companies are not looking to replicate what may be done at one of the sorting vendors’ testing facilities. Instead, they are looking at whether the material wants to respond to this type of particle sorting exercise in the first place and at what size fractions pre-concentration would make sense.

Should the indications prove positive, the information on what appears to be the optimal sort can be passed onto the vendors for more accurate follow-on testing of a bulk sample.

“In this way, we are qualifying the opportunity ahead of the vendors getting samples,” Dance said. “The vendors also have knowledge about how a sample has responded to amenability testing in the first place and what other tests were conducted concurrently.

“We will be providing complementary testing that will, ultimately, benefit the project in question.”

Dance says the aim is to create an industry standard test for pre-concentration that can be replicated by commercial laboratories all over the globe and is carried out routinely with hardness and crushing and grinding testing.

“One of the samples we have already tested was being assessed for rock hardness and we were able to offer them pre-concentration amenability results at the same time,” he said. “We’re not trying to provide the ultimate or ‘perfect’ test; it just needs to be a standard test that can be benchmarked and easily replicated across the industry.

“The value is in the data shared. People want to know how their sample compares with other operations, but this will only come with a large volume of testing.”

XRT scan results of particles
XRT scan results of particles

While XRT is first up, Dance says the company could soon add an X-ray Fluorescence option to the unit.

And, further out, he is confident this type of testing will open the door to more sensors coming into the mining sector outside of the ones already on offer.

“When we show the electronics industry that we have a viable market by dictating the terms of how we want to sort material through knowledge of such testing, the sensors will come,” he said.

“I’m not saying everyone should implement pre-concentration; far from it, as I expect a minority of the tests will show strong amenability. What I am saying is that everyone should test for it.

“By providing a no licence fee test that has no bias towards any vendor, we are allowing mining companies to scope that out.”

The venture is also part of Dance’s own ambitions to educate the mining sector on its waste-generating ways, he says.

“In the grinding space there is so much material that is recycled throughout the plant inefficiently,” he said. “We must question why we are putting things back in the mill to ultimately take it to tailings.

“There is simply no way we can carry on pursuing the economies of scale argument to reduce our energy consumption and water use. We need to embrace new technology in the right way – not running towards it but walking with purpose and data-backed decisions.”

NextOre and Pfeiffer to evaluate integration of MR bulk sorting and vertical roller mill tech

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NextOre Ltd says it has entered into a strategic cooperation agreement and a share subscription agreement with Gebr. Pfeiffer, a leading German comminution technology company.

Pfeiffer is a family-owned business with a 159-year history of innovation, specifically in mill technologies. Importantly, Pfeiffer is aligned with NextOre’s mission to deliver sustainable breakthroughs in processing technologies, NextOre says.

Under the strategic cooperation agreement, NextOre and Pfeiffer will collaborate to explore opportunities to combine their respective technologies to drive a step-change in efficient, environmentally-friendly minerals processing using:

  • NextOre’s magnetic resonance sensors and real-time bulk ore sorting to allow companies to achieve more metal production from smaller plants with lower environmental impact; and
  • Pfeiffer’s innovative vertical roller mill technology for dry grinding, which, it says, provides a substantial benefit in energy saving, delivers a uniform size reduction with a narrow particle size distribution, provides a high reduction size ratio of up to 1,000 and is highly flexible.

The first focus of NextOre and Pfeiffer’s collaboration will be on an integrated iron ore sorting and grinding solution for Brazil and Australia iron ore producers. NextOre and Pfeiffer have also identified a portfolio of copper projects that could see particularly strong results from the application of the two companies’ proprietary technologies to overcome their specific challenges.

Under the share subscription agreement, Pfeiffer has invested A$5 million ($3.2 million) through a placement of ordinary shares.

Pfeiffer’s investment follows NextOre’s successful completion of a A$5.2 million funding campaign in July 2023, which was underpinned by RFC Ambrian’s QCM fund – leaving the company well-funded to execute on its growth plans.

NextOre CEO, Chris Beal (above on the left), said: “We are delighted to welcome Gebr. Pfeiffer, a business with a long history of excellence supporting heavy industries, as a strategic partner and valued shareholder and look forward to creating real and sustained value as we advance the NextOre technology.

“We are excited at the opportunity to combine NextOre’s leading technology with Pfeiffer’s dry grinding technology, which is seeing rapid adoption into leading miners’ feasibility studies and which we see as a game changer for environmental sustainability.

“NextOre is undergoing a phase of significant growth. Pfeiffer’s investment in our business is a strong endorsement of NextOre’s magnetic resonance technology and recognition of its game-changing potential in the global resources industry.

“Like Pfeiffer, we are committed to creating solutions that our customers can rely on. We are excited to further prove NextOre’s real-world applications through this collaboration.”

Gebr. Pfeiffer’s CEO, Mathias Dülfer (above on the right), said: “Rising energy costs coupled with declining ore grades and the need for improved sustainability require new process technology. We are pleased to announce our partnership with NextOre to provide solutions that together can set a new standard.

“By investing in NextOre, a company that has developed this innovative and ground-breaking ore sensing technology over many years, we are building a strong foundation for a collaboration that will add sustainable value to the mining industry.

“The combination of Pfeiffer’s dry grinding technology for minerals with NextOre’s upstream sorting technology complements each other to increase production efficiency while reducing consumption of natural resources.

“Pfeiffer’s way of working has led to many breakthrough innovations that have resulted in our leading vertical mills. The cooperation with NextOre is another important milestone in this regard and a further contribution to the expansion of our mining activities. This is a consistent continuation of our strategic focus on efficiency, sustainability and digitisation.”

Sakatti-FutureSmart Mining

Anglo American highlights next FutureSmart Mining advances at Woodsmith, Sakatti

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Anglo American has provided its latest sustainability performance update, highlighting a number of technological advancements the company is looking to take at its in-development Woodsmith polyhalite mine in the UK and its exploration asset, Sakatti, in Finland.

Anglo American says it has an integrated approach to sustainability in project development, helping secure its ability to deliver responsible long-term growth in future-enabling metals and minerals.

The company is moving towards its goal of carbon neutral operations by 2040, evolving its pathways as it progresses, learns and as technologies develop.

At the end of 2022, its Scope 1 and 2 emissions were 21% below the peak levels of 2019 – a significant reduction that, Anglo American says, reflects its transition to 100% renewable electricity supply across its South America operations, with Australia to follow in 2025.

In southern Africa, it is working in partnership with EDF Renewables to build a 3-5 GW renewable energy ecosystem of wind and solar generation capacity, designed to tackle its largest remaining source of Scope 2 emissions and support energy reliability and grid resilience while catalysing broad socio-economic opportunities.

While Scope 3 emissions reduction is largely dependent on the decarbonisation of Anglo American’s value chains and the steel industry, in particular, it is progressing towards its ambition to halve these emissions by 2040.

Tom McCulley, CEO of Anglo American’s Crop Nutrients business, provided several references to Quellaveco, Anglo American’s most technologically-advanced mine that uses automation, a remote operations centre and high levels of digitalisation, when looking at its FutureSmart Mining™ plans at Woodsmith, a 5 Mt/y operation that could ramp up to 13 Mt/y.

McCulley, who also led development of Quellaveco, said Woodsmith will be developed as a benchmark for sustainable mining. This includes plans for the mine to be a low carbon, low water and low waste operation, with no tailings generation and with a minimum impact design.

“We hope this can show a way of how mining can be done in the future,” McCulley said of this approach at Woodsmith.

When it comes to Sakatti, Alison Atkinson, Projects & Development Director, said the development could end up being “our next greenfield project”.

The project is a rich multi-metal deposit with not only copper, nickel and cobalt resources, but also platinum, palladium, gold and silver.

“High concentrations of metal combined with consistency of the mineralisation between the boreholes make Sakatti a unique deposit,” Anglo American says of the project. Its resources are estimated to be sufficient for mining operations to last more than 20 years.

Atkinson said Sakatti is being designed as the next generation of FutureSmart Mining, building on what it has learned from Quellaveco and Woodsmith, particularly when it comes to ensuring there is minimal surface footprint and “using technology and innovations to deliver even better sustainability outcomes”.

She added: “Sakatti is set to be a remotely operated, low carbon-underground mine with an electric mining fleet using technology and mining methods that will create zero waste and enable high degrees of water recycling, contributing to a sustainable supply of critical minerals.”

The company also sees the potential to use sorting technologies for coarse particle rejection and material recovery opportunities.

South Crofty pre-con, ore sorting test work implies improved project economics, Cornish Metals says

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Cornish Metals Inc has received results back from TOMRA Sorting GmbH that indicate X-ray Transmission (XRT) sensor-based sorting could be a viable option for its South Crofty tin project in the UK.

The feasibility study on South Crofty, a iconic former producing copper and tin mine with first documented production history dating back to 1592, is advancing on schedule with a substantial amount of the study completed, Cornish Metals said. The mine was the last tin operation in Cornwall to close in 1998.

Metallurgical test work and heavy liquid separation (HLS) pre-concentration test work provided “excellent results”, the company said.

Conducted on samples from the 2023 metallurgical drill program across five mineralised zones (No. 4 Lode, No. 8 Lode, Roskear B/D Lodes, North Pool Zone and Dolcoath South), it represented the majority of the potential production areas in the first six years of the proposed mine life, according to Cornish Metals.

The XRT work came back with a 55% mass rejection and less than 3% metal loss (-50 mm – +15 mm size fraction), while the HLS testing saw a 50% mass rejection and lesss than 5% metal loss (-15 mm – +0.85 mm size fraction).

The XRT ore sorter test work of bulk composite samples was completed by TOMRA Sorting GmbH, with the HLS test work of bulk composite samples completed by Wardell Armstrong International.

Cornish Metals said: “The test work results confirm the upgrading potential of South Crofty mineralisation and enables continuation of the process design optimisation work to reduce the size of the mineral processing plant and materially lower capital costs, operating costs and environmental footprint.”

Richard Williams, CEO and Director of Cornish Metals, said the company expected the mineralisation at South Crofty to respond well to XRT ore sorting, but these results exceeded “our most optimistic expectations”.

He added: “We expect this result will have a positive effect on the project economics, allowing for lower power consumption and a smaller process plant and therefore lower capital and operating costs.”

In addition to ore sorting test work, the following feasibility study components have also been completed:

  • Headframe structural modelling and refurbishment;
  • Schedule and costing for the refurbishment and recommissioning of New Cooks Kitchen and New Roskear shafts;
  • Televiewer investigations and geotechnical rock testing to confirm known historical structural and rock mass property data;
  • Conceptual numerical modelling of the proposed underground mining methods and stope designs. Back analysis supports historical operating data. Ground conditions and excavation stability are expected to be very good;
  • Phase 1 of the metallurgical testwork program (mineralogy, physical competency, characterisation and gravity response test work). The gravity response results are very good and confirm previous operational results;
  • Concept engineering on paste backfill options and sighter test work; and
  • Ground investigations for the new mineral processing plant.

The following dtudy components are currently underway:

  • Mineral processing plant design, layout and capital cost study, incorporating the results of the metallurgical test work program reported today and potential future throughput expansions;
  • Underground mine design and optimisation using the latest South Crofty resource estimate published in September 2023;
  • A mine ventilation study, underground infrastructure design and hoisting analysis;
  • A feasibility study-level engineering design for the paste backfill plant;
  • Hydrogeology, environmental, social, marketing and closure studies; and
  • AMC Mining Consultants has been appointed to independently review and compile the feasibility study with initial gap analysis and site visits completed.