Tag Archives: XRT

SRK’s stepwise approach to pre-concentration analysis

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

SRK Consulting, Base Metallurgical Labs tackling pre-concentration amenability

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.”

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

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.

TOMRA Mining talks sulphide ore sorting in copper, zinc, lead space

When processing sulphide ores to extract copper, zinc or lead, the focus is on ensuring that the mill is always operating at full capacity. The challenge is to optimise the process by eliminating waste in the early stages and maintain a high recovery rate, TOMRA Mining says.

This means that less barren or low-content rock will be processed, consequently increasing the metal content in the input of the mill. The result: significant cost savings and reduced environmental impact per produced tonne of metal.

In the case of copper, the mineralogy and lithology of the ore will affect how effective sorting can be at removing waste. When sorting copper sulphides with a non-disseminated texture, the focus is on waste removal to maximise recovery. However, three quarters of global copper production come from porphyry deposits, where very small grains of the metal are disseminated, making detection particularly challenging. Zinc and lead sulphides present similar sorting challenges to non-disseminated copper, although the metal content in the mineral is typically higher, so the focus will be on waste removal while maintaining the recovery levels.

The technology to sort copper, zinc and lead sulphides effectively to optimise the process is available from TOMRA Mining, it says. Its X-ray Transmission (XRT) sensor-based sorting technology can effectively detect sulphides in mineralised run of mine materials as they carry elements with higher atomic densities than non-mineralised waste rocks. After crushing, the ore in a size range from +8 mm to 80 mm is fed into the sorters and the barren and low content rocks are eliminated, resulting in a higher head grade of the mill feed. In addition, the eliminated waste can be replaced in the mill with more upgraded sulphides, increasing the efficiency of the mineral process.

However, in order to maintain the capacity of the mill, it is necessary to increase the amount fed to the crusher. This will have an impact on the mine and extraction planning. Due to the lower processing costs of sensor-based sorting, it is also possible to bring this in the calculation of the resource evaluation and the final pit design, according to TOMRA Mining.

TOMRA’s XRT sorters scan the individual rocks fed into the machine on a conveyor belt with overhead X-ray sources. At the same time, detectors located inside the belt collect data from the ore. The position of sensors, close to the rocks, combined with the strong X-ray power sources result in extra high-resolution images. This enables TOMRA’s XRT sorters to effectively process even most of the challenging porphyry copper disseminated deposits. Waste rocks are ejected by high-precision, fast pneumatic module, which adds to the sorter’s efficiency.

In copper sulphides with disseminated texture, a TOMRA XRT sorter can achieve an upgrade ratio of copper content in the mill feed ranging from 20% to 100%, while separating 20%-45% of mass as the waste material. With porphyry copper, the cut-off grade is typically 0.5%, but in view of the surging demand, it is now often as low as 0.2-0.3%. With TOMRA’s XRT technology, it is possible to achieve high recovery rates even at the lower grade, as shown by the tests conducted on run-of-mine samples from at OZ Minerals’ Antas Norte mine, in Brazil, the company says. The sorter demonstrated its ability to achieve recovery rates of at least 90% or reduce the waste grade down to 0.3% copper.

Heitor Mesquita Carmelo, Plant Manager at OZ Minerals Brazil, explains: “A bulk test was conducted to evaluate TOMRA’s XRT technology, and subsequently, the company decided to test it continuously in a pilot installation at the Antas Norte site. The results were consistent in both tests, demonstrating that the technology is effective for industrial application. TOMRA’s technology holds significant potential for OZ Minerals Brazil’s strategic plan, with the possibility of making deposits with lower ore grades viable, reducing operational costs, enhancing transportation safety for pre-concentrated ore, as well as decreasing the CO2 emission resulting from this activity.”

Heitor Mesquita Carmelo, Plant Manager at OZ Minerals Brazil

In lead and zinc sulphides, tests conducted by TOMRA have shown that it is possible to achieve an upgrade ratio of two to three times lead or zinc in the output of the sorter. Here the mineralisation plays an important role and can dramatically affect the upgrade ratio, TOMRA Mining says.

TOMRA’s XRT sorter delivers multiple benefits for copper, zinc and lead mining operations, beginning with its uniquely high capacity, which can be as high as 150-200 t/h per sorting width meter – a differentiator of TOMRA’s which also meets the requirements for medium- and large-size operations, it says. The sorter’s operational efficiency can be further improved with TOMRA Insight, a cloud-based subscription service that turns the sorter into a connected device that generates process data. It enables mining operations to monitor and measure performance in real time and optimise the process as well as tracking faults to improve maintenance and keep the plant always operating at its best.

Another important benefit of the sorter is the capacity to lower operating costs through its efficiency and energy saving features such as its ejection module that uses compressed air to eject the particles – up to 80% less compared to other ejection systems – dramatically reducing energy consumption compared to conventional sorting machines.

Optimising the process also reduces its impact on the environment. In addition, TOMRA’s XRT technology is a dry process, so that the overall use of water and chemicals is also reduced.

HPY ore sorting tech helps Xintianling Wolfram Mine achieve sustainability goals

Xintianling Wolfram Mine in China has partnered with HPY Technology to upgrade the ore content and reduce the amount of tailings being processed at its operation in China.

Established in 2008, Hunan Nonferrous Metals Xintianling Wolfram Mine Co., Ltd. (Xintianling Wolfram Mine) represents the largest individual producer of tungsten concentrate in China. With a processing capacity of 1.5 Mt of ore, the mine produces 5,000 t of tungsten concentrate annually. The company is engaged in mining, beneficiating and tungsten ore sales, along with molybdenum and bismuth recovery.

Xintianling Wolfram Mine is a subsidiary of China Tungsten and Hightech Materials Co. Ltd., which is the management and operation platform for the tungsten industry owned by China Minmetals Corporation. A Fortune 500 company, China Minmetals manages and operates a complete tungsten industry chain that integrates mining, smelting, processing and trading. Its management area contains 1.23 Mt of tungsten resources, representing approximately 11% of China’s identified tungsten resources, according to the company. Its annual production capacity for tungsten smelting reaches 20,000 t, constituting 10% of the total capacity for ammonium paratungstate in China.

In its early years, Xintianling Wolfram Mine used shorthole blasting as the primary mining method. While this method leads to low ore depletion rates, it comes with drawbacks such as low mining efficiency, high costs, low mechanisation and high safety risks. In response to these challenges and production requirements of a 4,500 t/d reform and expansion project, the mine transitioned to medium-deep hole blasting methods for mining. This change, however, introduced issues of higher depletion rates, decreased ore grade and increased beneficiation production costs.

A significant challenge faced by the Xintianling Wolfram Mine is the production of over 1.3 Mt/y of tailings, consuming over 1 million sq.m of tailings reservoir capacity. With the existing tailings pond projected to meet production needs for only five more years, the mine needed to enrich the raw ore grade, reduce the amount of tailings entering the tailings pond, and lower the amount of material entering its grinding and flotation processes to adhere to its commitment to sustainable mining.

To tackle these problems, Xintianling Wolfram Mine partnered with HPY Technology in early 2021, seeking a method to solve its technical challenges and for a more sustainable process. HPY’s sensor-based ore sorting technology could help with these aspects, the technology company says. X-ray Transmission (XRT) detection is commonly used in the mining industry to analyse the atomic density differences in ores. XRT relies on the principles of X-ray absorption and attenuation to differentiate between various materials based on their atomic densities. The tungsten ore is first crushed into a smaller particle size, with the material then fed into the sorting machine, which uses X rays to detect differences in the ore. By measuring the degree to which the X rays are absorbed by the ore, the machine can distinguish between different types of material. As tungsten absorbs X rays very strongly due to its high atomic number and density, it is relatively easy to be identified through this method, according to HPY.

Even so, the raw ore of the Xintianling Wolfram has its own special characteristics. The mineral composition of the raw ore at the Xintianling Wolfram Mine is quite complex. Various minerals in the raw ore can be imaged under radiation, including tungsten minerals, metallic sulphides, iron minerals and denser gangue minerals. However, the most finely embedded tungsten cannot be captured and effectively identified in the image due to the varying particle sizes in the raw ore. Solving this problem requires high-precision imaging capture and ore identification by a sensor-based ore sorting machine. At the same time, the raw ore itself has a small particle size. Therefore, the image of the ore is relatively small, resulting in an increase in the amount of ore to be processed for the same processing capacity. It was a technical challenge for HPY to improve the processing capacity while maintaining a low waste rock grade and rejection rate.

HPY conducted on-site research, sampling, testing, simulation and analysis at the Xintianling Wolfram Mine. The Classic Series was used during the early stages of the experiment. The middle and later stages saw the introduction of the Circle Series – HPY Technology’s ring-shaped structure design that, the company says, allows for exceptional processing capacity within a compact frame. Through continuous optimisation of the software, modification of equipment adaptability, and fine-tuning of the artificial intelligence-based algorithm, the engineers succeeded in reducing the rejection rate and stabilising the waste rock grade, the company said. As a result, the experiment reached its desired goals and Xintianling Wolfram Mine was satisfied with the sorting results.

Ganzhou HPY Technology Co., Ltd., is a high-tech enterprise specialising in the development and manufacture of ore sorting machines. The company’s AI technology includes perception technology, human-computer interaction and deep learning. The performance of HPY’s technology in the Xintianling Wolfram Mine project demonstrates its effectiveness in addressing the challenges of sustainable mining, the company says.

Xintianling Wolfram | HPY Technology

Particle size +10-35 mm Raw ore grade  0.15%-0-40% WO3
Rejection rate 25% Waste rock grade 0.04% WO3
Recovery rate >94% Processing capacity 80-90 t/h
Enrichment ratio >1.4    

TOMRA’s latest XRT advances open up processing options for miners

When it comes to particle sorting, size is everything. Whether used as a primary sorting method in smaller operations where product purity is paramount to profits, or in a scavenger setup downstream to capture value once lost to tailings, particle sorters are becoming more and more commonplace across the mining world.

They have featured in flowsheets in the industrial minerals space for decades, but they are now finding their way into metal operations all over the world as miners look to boost recoveries, reduce their energy consumption and, in many instances, rationalise their water use.

This makes TOMRA Mining’s latest advances in sensor-based ore sorting all the more significant.

The company is now breaking ground with a new ejection module for its COM Tertiary XRT (X-ray Transmission) sensor-based sorter specifically developed for sorting small particle sizes.

The COM Tertiary XRT Fines sorter, featuring the new TS100C module and the recently introduced image processing unit, is capable of sorting particle sizes down to 4 mm in high-capacity applications with much higher energy efficiency, delivering a high-quality product at low operating costs, according to the company.

The COM Tertiary XRT Fines sorter featuring the new TS100C ejection module has been installed at the TOMRA Test Center in Wedel, Germany

The high resolution TS100C ejection module features a new type of ejector that is four times faster than previous iterations, according to the company. Together with the new image processing unit, it delivers higher precision in sorting small particle sizes at high throughputs.

The mechanical design of the sorter has also been improved by the introduction of a new splitter plate and more precise calibration equipment to ensure the greater precision in the alignment between detection and ejection systems required for fine particles, according to TOMRA.

This has been captured in field tests that started back in May 2022, showing an up to 30 t/h boost in capacity, an increase in product recovery and a reduction in energy consumption.

Ines Hartwig, Director Product Management at TOMRA Mining, told IM on the side lines of the recent SME MINEXCHANGE 2023 Annual Conference & Expo in Denver, that the company had been able to visualise such small size particles previously, but the mechanical ejection function had not been able to keep up.

“This new ejection module is a significant leap forward for TOMRA, and we believe the whole particle sorting setup within the industry,” she said.

And, while the industrial minerals sector was the first one pushing for these developments, Hartwig said she expected the metal miners to also benefit from this.

“We have visited operations all over the world that have stockpiled fine material as they simply couldn’t process it with the technology on the market,” she said. “We’re now opening up many new opportunities for these companies.”

To gain field experience on the new ejection module, TOMRA partnered with a customer who has been running a COM Tertiary XRT to produce high-grade magnesite for more than two years. The sorter removes up to 50% low-grade and waste material from the raw magnesite feed, with particle sizes ranging from 10 to 35 mm at about 20 t/h.

Ines Hartwig, Director Product Management at TOMRA Mining

“After conducting the test work with the TS100C ejection module at the TOMRA Test Center, we were confident that it would be very beneficial for this customer,” Hartwig says. “We showed them the test results and outlined the benefits we expected the module to deliver. As soon as they saw the possible reduction in compressed air use and the consequent cost savings, they were very interested in doing the field trial!”

The customer, the magnesite operation in Turkey, completed several trials, documenting the energy savings and sorting efficiencies. The results showed a 70% reduction in air consumption with an increase in product recovery with a lower mass pull to waste by producing the same product quality, and a capacity increase ranging from 20 t/h to 30 t/h with comparable results, according to TOMRA.

The COM Tertiary XRT Fines sorter featuring the new TS100C ejection module has been installed at the TOMRA Test Center in Wedel, Germany, and is ready to run tests for customers on material samples from their mines, TOMRA says.

Hartwig said she expected existing COM Tertiary XRT customers to upgrade to the new module with the company’s retrofit solution, but there were also many new customers expected to acquire brand-new units.

“There is a significant ‘new’ market out there that we expect to take advantage of this technology,” she said. “The economic and environmental value case at many of these operations can be vastly improved by using the COM Tertiary XRT Fines sorter.”

TOMRA XRT ore sorters providing Mt Carbine with tungsten upgrade, circular economy advantages

TOMRA X-Ray Transmission (XRT) sorters are providing a game-changing solution for the EQ Resources-owned Mt Carbine mine in Queensland, Australia, reducing costs and achieving high-purity tungsten ore for follow-on processing while contributing to a circular economy by producing green aggregates for sale, the ore sorting company says.

The Mt Carbine mine, northwest of Cairns, Queensland, was acquired by EQ Resources in 2019. The company entered a joint venture with Cronimet Group to set up tungsten extraction from the mine’s large waste dump and tailings. It is also planning to operate the open pit and underground mine, of which it has full ownership.

EQ Resources management has a long-standing relationship with TOMRA, having used its sorters with success on a variety of projects since 2011, TOMRA says. Based on this experience, the company turned to TOMRA once again for the Mt Carbine mine, with test work conducted at TOMRA’s Test Center in Wedel, Germany, confirming its XRT technology would provide the solution for the project.

“We were confident it would work, but we sent a small sample for testing to make sure,” Kevin MacNeill, CEO of Mt Carbine mine, EQ Resources, said. “The advantage of TOMRA’s sorters compared to others is in the image resolution: it is able to resolve the finer inclusions in the tungsten. This high resolution gives us better recovery and more control over the sorting process.”

Mt Carbine is currently mining the 12 Mt of low-grade historical stockpiles. The ore is crushed and screened at 6 mm and 40 mm. Two TOMRA XRT sorters are used to pre-concentrate the feed in the 6-40-mm-size range before processing in the wet plant. Approximately 10% of the sorters’ feed mass is ejected as product with a recovery of tungsten of well over 90%. This means only 10% of the mass is processed in the wet plant, dramatically cutting running costs, reducing the required size of the wet plant, as well as saving water and energy, TOMRA says.

“We let the technology do the work for us and take out all the rubbish and we’re left with just the pure tungsten to send to the processing plant – and we do that very cheaply using the sorters,” MacNeill says. “One of the best things about the TOMRA XRT is the cost savings to the operation. It costs approximately A$1.5/t ($1.02/t) to sort and then it costs A$14/t for wet processing: as we take out 90% of the sortable fraction mass, we only have to process 10% of the higher grade concentrate and natural -6 mm material while maintaining recovery, so our cost benefit is obvious.

“We couldn’t afford to run this waste dump if we had to crush everything to 6mm and process it through the wet plant, it would be too low grade and costly.”

EQ Resources is also taking advantage of the TOMRA XRT sorters to create an additional revenue stream from the waste material.

MacNeil explained: “Normally you would grind the waste down to 6 mm and put it through the jigs, but, by putting it through the TOMRA sorters, we are able to keep a whole range of aggregates on the coarser size fractions. The sorters remove any material containing acid-forming sulphides and the waste rock that comes out is incredibly clean. We are, therefore, able to use it in making all kinds of different quarry products – from road bases to concrete aggregates. It’s a perfect example of a circular economy.”

“Selling these green aggregates adds a significant portion to our business – about A$5 million a year – and that’s all because of the TOMRA sorters. In fact, we’ve probably paid for each machine from this revenue five times over.”

The TOMRA XRT sorters are delivering both environmental and business benefits to the Mt Carbine operation, to the satisfaction of MacNeill: “They’re dry, they create no water usage, they require very little power compared to what we use in the processing plant, so it’s a real advantage to us to have these, and we’re looking at purchasing a third one in the near future.

“From an environmental point of view, I think the TOMRA sorters will play a huge role in the future because of their capability of removing sulphides. If you remove sulphide before stockpiling waste rock, you will have the benefit of no acid creation and drainage – and it would reduce your footprint in your closure plans.”

TOMRA Mining to demonstrate Final Recovery diamond sorter at Electra Mining 2022

TOMRA Mining will showcase its sensor-based sorting solutions at the Electra Mining 2022 exhibition, in Johannesburg, South Africa, in September, showcasing, for the first time, live demonstrations of its COM XRT 300 /FR Final Recovery sorter for diamond operations.

Representatives from its Sales and Field Service teams will also present TOMRA’s offering of advanced digital products and services, such as the TOMRA Insight cloud-based platform and its latest generation TOMRA ACT PC-based system, as well as its portfolio of sorting solutions for the diamonds, metals and industrial minerals industry at the show, which runs from September 5-9.

Corné de Jager, Diamond Segment Manager TOMRA Mining, said: “The Electra Mining Show is the perfect platform for us to showcase TOMRA’s advanced mining solutions. This important exhibition attracts a wide audience – from operators and metallurgists – interested in smart solutions that are simple to operate and maintain, to decision makers who need to be up to date with the latest value-adding technologies. At the event we will have the opportunity to meet them face-to-face and discuss their requirements, giving them a taste or TOMRA’s collaborative approach, product expertise and after-sales support.”

TOMRA will demonstrate the Final Recovery sorter with fine kimberlitic or alluvial ore together with diamond powdered tracers in a Final Recovery and Sort House application. Visitors will be able to experience first-hand the sorter’s capability to produce an ultra-high diamond-by-weight concentrate with an exceptionally low yield by using TOMRA’s proprietary ultra-high-resolution sensor, advanced new image processing and high-precision ejector valve system, the company says. The sorter offers 100% diamond detection within the specified size fraction and > 99% guaranteed diamond recovery with appropriate feed material preparation.

“We are very excited to demonstrate the TOMRA COM XRT 300 /FR sorter,” de Jager says. “It completes our unique partnered diamond recovery ecosystem, which covers the entire process. We are now able to offer our customers a full XRT solution to sort +2-100 mm particles: +4-100 mm particles with our bulk concentration sorters, and +2-32 mm particles with the COM XRT 300 /FR in its Final Recovery, Sort House or small-capacity exploration applications. The sorter offers higher efficiency, better grade, simplified security requirements with fewer sorting stages and a smaller footprint. It reduces complexity and operational costs, and unlocks the potential for previously deemed non-profitable projects and marginal deposits to be economically viable. ”

The COM XRT 300 /FR sorter can also add value to existing kimberlitic and alluvial operations that use conventional bulk-concentration methods like rotary pans, dense medium separation or X-ray luminescence, if installed in a Final Recovery and/or Sort House function after these existing processes. With a contained capital expense, operations can benefit from a quick, simple and significant revenue gain, TOMRA says.

The TOMRA team at the exhibition will explain the full benefits of its complete partnered diamond recovery ecosystem consisting of XRT technology covering the entire process – from Bulk Concentration to Final Recovery and Sort House applications – as well as its advanced digital products and services. These include the newly refreshed TOMRA ACT PC-based system interface and TOMRA Insight cloud-based subscription solution.

TOMRA Mining has 190 sorter installations operating around the world, of which more than 60 are in Africa. It offers installation opportunities in Africa in the metals industry, for example in applications such as lithium, chromite, platinum, manganese and gold.

Tungsten West breaks ground at Hemerdon for TOMRA XRT ore sorters

Tungsten West says it has broken ground at its Hemerdon tungsten-tin mine in Devon, England, with the first sod turned for the installation of the TOMRA X-ray Transmission (XRT) sensor-based ore sorters.

This event, the company says, marks another major step in the company’s upgrade and refurbishment plans for the project’s processing plant.

Hemerdon is, Tungsten West says, the third largest tungsten resource globally, as well as being a previously producing mine that was operational from 2015-2018. Tungsten West purchased the Hemerdon Mine in 2019, and has since completed a bankable feasibility study that demonstrated an extensive reserve of approximately 63.3 Mt at 0.18% W and 0.03% Sn, as well as 37.4 Mt of saleable aggregate material. The company estimates that the life of mine is currently 18.5 years with the opportunity to extend this through future investment.

As announced earlier this month, the company took receipt of important long-lead equipment items, including the seven XRT ore sorters, which will make up part of the upgraded equipment the company plans to install into the front end of the processing plant. The XRT ore sorter will substantially improve and streamline operations once production restarts, minimising plant downtime, increasing recovery as well as a host of ESG benefits, it said.

After significant test work, Tungsten West engaged TOMRA to supply the seven units that are required to treat the run of mine throughput. This consists of six duty units and one standby unit. Orders and deposits for these units were placed in 2021 and the units have now been delivered to the UK and await final transfer to Hemerdon where they will be installed in the front end of the processing plant.

Additionally, the company is pleased to announce the appointment of James McFarlane as Managing Director of Tungsten West. McFarlane previously held the position of Technical & Operations Director of the company.

Max Denning, Tungsten West CEO, said: “We are extremely excited to have broken ground at Hemerdon this week, marking an important milestone in the project’s restart. Ensuring the UK and the western hemisphere have got access to two key critical minerals has never been more profound. We are also delighted to announce James as our new Managing Director; his extensive experience will prove invaluable in the company’s development as we move closer to first production at Hemerdon.”

TOMRA continues to build ore sorting Insight across mining space

Some 18 months after launching TOMRA Insight to mining customers, the cloud-based data platform is making inroads across the North American mining sector, Harold Cline and Jordan Rutledge told IM on the side lines of the MINEXCHANGE 2022 SME Annual Conference & Expo in Salt Lake City recently.

TOMRA rolled out the subscription-based service to mining back in late 2020, with one of the early adopters being the Black chrome mine in South Africa, one of two mining projects that form the basis of the Sail Group’s plans for long-term sustainable chrome production.

TOMRA Insight, the company says, enables sorting machine users to improve operational efficiencies through a service that turns these machines into connected devices for the generation of valuable process data.

Cline and Rutledge, both TOMRA Sorting Area Sales Managers for North America, said numerous customers were now taking advantage of TOMRA Insight across the region, with many more interested in leveraging the continuous data streams coming off a web-based portal stored securely in the cloud.

TOMRA’s Harold Cline & Jordan Rutledge

“This is seeing mine managers able to tap into how operations are performing today, while tracking that against performance over the last day, week, month, quarter, etc,” Cline told IM. “With the help of our support network, these operations are able to achieve more consistent performance.”

With more customers signing up to TOMRA Insight and more data being generated, the pair were confident future iterations of the platform would be able to offer machine-learning algorithms that helped, for example, predict failures or highlight potential areas for operational improvements.

At the show, the pair were also highlighting the ongoing demand for TOMRA’s Final Recovery sorter, the COM XRT 300/FR, which, since launch, has been successfully deployed at the Letšeng diamond mine in Lesotho, owned by Gem Diamonds. The solution has gone on to be rolled out at other operations.

The introduction of the COM XRT 300/FR, TOMRA became the first company in the industry able to supply a full diamond recovery solution using XRT technology from 2-100 mm, with the unit delivering concentration factors of up to one million with limited stages and guaranteeing more than 99% diamond recovery, according to the company.

Outside of diamonds and sorter analytics, Cline was keen to talk up demand from the gold sector for the company’s sorters.

One of the key differentiators of its offering to the yellow metal space is the ability to scan the material with a multi-channel laser sensor. In an ore sorting setup that involves both XRT and LASER sensor-based machines, the TOMRA solution can remove particles containing sulphide minerals using XRT and subsequently leverage laser sensors to remove particles containing quartz and calcite.

TOMRA says its segregated option can potentially improve recoveries in quartz-associated gold applications thanks to a laser chute-based machine that analyses rocks from both sides. Other belt-based laser machines can only analyse a maximum of 40% of the rock’s surface, according to TOMRA.

“In the gold scenario, we are using XRT to sense and sort with sulphide minerals as a proxy,” Cline said. “At the same time, our laser scanner allows further separation capabilities through identification of minerals such as quartz and calcite.”

Vista Gold, which is developing the Mt Todd project in Australia, anticipates that this combined solution could eliminate approximately 10% of the run-of-mine feed to the grinding circuit, allowing the company to decrease the grind size and thereby increase recovery of the contained gold.

The COM XRT 300/FR offers a full diamond recovery solution

Cline added: “In North America, we have three projects in the gold space we’re working on at the moment that appreciate our unit’s ability to analyse the whole of the particle through our chute mechanism, as opposed to conveyor-based systems that can only analyse one angle of the particle.”

While TOMRA offers multiple sensors on its units through its modular platform, Rutledge said the company continues to have discussions on combining its solutions with other bulk sorting suppliers to further improve the process, naming prompt gamma neutron activation analysis (PGNAA) technology as one specific area of interest.

“We very often refer clients on to other companies when our solution may not match their brief,” she said. “At the same time, we have done some flowsheet work to include our solution with others currently on the market and believe it is only a matter of time before a combination of the two comes into a flowsheet.”