Tag Archives: x-ray fluorescence

The role of automated sampling and analysis in mining

Automation, Base metals, Environmental, Metallurgy, Mining equipment, Mining services, , , ,

A high demand for commodities gives producers and manufacturers both opportunity and motivation to become more efficient, pragmatic and automated, Evident Scientific* says.

With the high prices comes shorter contracts with specifications that can change from week to week. This gives miners and recyclers an added challenge in streamlining their operations.

Varying grades and penalty elements mean both mines and smelters need to have accurate chemical analysis, low bias port-to-port and fast information in as close to real time as possible to be effective to production. Mine managers will agree improved data accuracy leads to better extraction at the pit, optimised blending of material, reduced penalty elements and improved output, which overall means better profitability.

Most on-site labs usually run 4-5 hours behind production, often more when using third-party remote laboratories. This can cause delays ranging from hours to days. Manually collected samples may provide little in bulk material representativity. Most sampling experts recognise that many bulk material biases come from sampling and less from the technique. Automating this process and bringing the laboratory to the samples increases productivity, reduces bias and improves overall accuracy.

The key here is not to bring the analyser to the belt but to bring the lab sample prep technique to the belt. Many on-belt analysis techniques try to measure concentration on the belt and are faced with the varying nature of materials on the belt, making it impossible to get consistent enough reading for accurate analysis.

Automatic on-belt sampling system solution

To solve this issue of inaccurate on-belt sampling and analysis, X-ray Fluorescence (XRF) technology, which can identify and quantify the composition of minerals in seconds, is an essential component. The second part required for an effective on-belt sampling solution is an automated mechanism that collects and prepares samples of bulk mined material, such as coal, aluminium, titanium, iron, manganese, nickel and copper ores. The well-prepared samples are presented to the in-line XRF analyser to obtain fast, automated and accurate analysis of the material, removing bias from moisture, mineral interference, grain size and many other obstacles you get from trying to sample directly on the belt.

Three-step process for automated on-belt analysis

The following describes the step-by-step process of such an automated on-belt system once implemented in the mineral processing line.

  1. Automated collection of mined materialsThe system automatically collects the samples from the belt at intervals that the user can set. The mechanism is a cross-belt sampler that does not stop or slow the belt. The sampler can be adjusted to any conveyor belt and processed using the plant’s distributed control system (DCS) to ease operations. The collection process complies with the following standards:
    • ISO 12743 (Cu, Pb, Zn, Ni);
    • ISO 13909, ISO-3082 (Fe);
    • ASTM E877 (chemical analysis); and
    • ASTM D7430.
  2. Automated sample preparation for XRF analysis of mined materials
    Some 15 kg of collected samples are first crushed from 50 mm to 4.5 mm (Crusher 1) and from 4.5 mm to 200 µm (Crusher 2) into a 500 g puck. The moisture content is taken and recorded to remove measurement bias. The samples are pressed and ready for chemical analysis using XRF. The entire preparation process is automatically controlled and monitored.
  3. Real-time chemical analysis of mining feed material on the belt
    The prepared samples are then analysed using the in-line XRF analyser. For this system, the XRF analyser chosen features a fast and highly accurate AI-inspired dynamic method that is flexible and able to deal with multiple matrices at the same time.
    It also offers the following capabilities:

    • Excellent sensitivity to trace elements;
    • Quantification of up to 30 elements in one measurement;
    • Detection down to 1 ppm for critical elements; and
    • Analysis of light elements, including magnesium, aluminium, silicon and sulphur.
Figure 1. Cross-belt sample collection system
Figure 2. Samples after preparation
Figure 3. In-line XRF analyser on a sample

Benefits of implementing an automated in-Line XRF sampling system on the belt

Profitability in data: real-time analysis

This system’s in-line XRF analyser enables real-time automatic, continuous, rapid and accurate laboratory-quality measurements without delay, using advanced processing technology that enables higher count rates and fast results (99.97% accuracy). All inputs are streamed directly to the plant control systems. The high accuracy of bulk mined materials will assist in efficient decision making for material blending and sorting.

Profitability in accuracy: improving revenue

To minimise penalty fees, continuous accurate results of the mined ore going through the conveyor belt are necessary. However, various size samples can lead to inaccurate results that do not represent the ore extracted. A homogeneous subsample will give a better representation of the ore tested.

The automated on-belt system with its XRF technology minimises this bias by bringing laboratory results on site using homogeneously prepared samples to achieve accurate inputs so mining operations are better managed:

  • Provides representative, unbiased samples;
  • Avoid inaccurate chemical results;
  • Zero impact on belt speed;
  • Quality control of the ore grade;
  • No penalty fees; and
  • Optimise profitability.

Profitability in asset management: crushing

Comminution, as the most significant process operation in minerals processing, is essential to exercise due diligence to maintain the assets in continuous operations by limiting downtime and optimising your investment lifecycle. However, unexpected rock hardness can limit the crusher’s lifespan. Real-time analysis with mechanical sampling can give you the exact rock composition to help you choose the right tool for the right rock to maximise your assets’ return on investment and reduce maintenance costs.

On the mining processing side, knowing your rock composition can guide you in adapting your crushing priority in real time based on the incoming rock hardness by using the automated in-line XRF system. Obtaining the composition results rapidly can also improve your efficiency in concentrating critical ore from embedded matrix materials.

Profitability in knowledge: improving blending and treatment process

The treatment process is the first step toward getting a more concentrated ore blend. It is crucial to achieve this step correctly and, more importantly, to identify any mistakes to act on time. Regular laboratory analyses cannot be conducted as the results on incoming head grades will come too late to correct errors.

Real-time analyses can give you the correct data at the right moment to guide you in the treatment process of your ore. You will almost instantly know whether you should add an extra process to remove an element compound to achieve the researched concentrated blend. Furthermore, you could give hourly reports to your geologist in terms of ore grades.

Additionally, the data can help you recover the concentration/grade intended – reducing waste and keeping the blend in line with your customer request – and minimise the use of acid or other leaching compounds. Everything toward managing penalty elements and improving your overall blending.

Profitability in safety: tailings management

Tailings are an inevitable process where all the unrecoverable and uneconomic remnants from mining processing can reach immense proportions and become problematic if not properly managed. The automated on-belt sampling system can help manage your tailings by giving you real-time information on any high-level concentration of problematic/sensitive elements (S, As, Pb, etc). You can not only effectively manage your tailings but also get input on how to better store and treat the by-product.

Automated on-belt sampling plus XRF equals increased profitability

Any improvement can have significant repercussions in an industry with many processes and production challenges. Automated on-belt sampling and analysis can improve your mining workflow at critical steps and protect your profitability.

An automated in-line sampling system powered by XRF analysis technology enables you to perform on-site laboratory-grade testing and obtain real-time inputs in an industry where time can be critical. XRF technology brings accuracy even for some critical light elements, and is safer and easier to operate than other analytical options.

Like the old adage goes: time is money, so implementing an automated in-line sampling system that can reduce the mineral processing workflow by hours and possibly days could have a major impact on your bottom line.

*This article was written by Evident Scientific, formerly Olympus Industrial

Hudbay’s Constancia continuous improvement quest leads to MineSense XRF trial

Base metals, Comminution of minerals, Environmental, Mine operation news, Mineral processing, Mineral project development, Mining equipment, Sustainable mining, Water management, , , , , , , , , , , , , , , , , , , ,

Hudbay Minerals has one of the lowest cost per tonne copper sulphide operations in Peru on its hands at Constancia, but it is intent on continuously improving the mine’s margins and environmental performance through a commitment to continuous improvement. This has recently led it to exploring the potential of sensor-based ore sorting.

Hudbay’s operations at Constancia include the Constancia and Pampacancha pits, an 86,000 t/d ore processing plant, a waste rock facility, a tailings management facility and other ancillary facilities that support the operations.

The company increased reserves at the mine, located in the Cusco department, by 33 Mt at a grade of 0.48% Cu and 0.115 g/t Au last year – an increase of approximately 11% in contained copper and 12% in contained gold over the prior year’s reserves.

With the incorporation of Pampacancha and Constancia North, annual production at Constancia is expected to average approximately 102,000 t of copper and 58,000 oz of gold from 2021 to 2028, an increase of 40% and 367%, respectively, from 2020 levels, which were partially impacted by an eight-week temporary mine interruption related to a government-declared state of emergency.

Constancia now has a 16-year mine life (to 2037) ahead of it, but the company thinks there is a lot more value it can leverage from this long-life asset and it has been looking at incorporating the latest technology to prove this.

In recent years it has, for instance, worked with Metso Outotec to improve rougher flotation performance at Constancia using Center Launders in four e300 TankCells and installed a private LTE network to digitise and modernise its open-pit operations.

Peter Amelunxen, Vice President of Technical Services at Hudbay, said the Constancia ore sorting project – which has seen Hudbay partner with MineSense on a plan to trial the Vancouver-based cleantech company’s ShovelSense X-ray Fluorescence (XRF)-based sorting technology – was one of many initiatives underway to further improve the operating efficiency at Constancia.

“The ore sorting program is separate from the recovery uplift program at Constancia,” Amelunxen said, referring to a “potentially high-return, low capital opportunity” that could boost milled copper recovery by 2-3%.

He added: “The ore sorting program is expected to yield positive results at the mining phase of the operation and is expected to increase the mill head grade and reduce metal loss to the waste rock storage facility.”

Back in April 2021 during a virtual site visit, Hudbay revealed it was trialling bulk sorting at Constancia as one of its “optimisation opportunities”, with Amelunxen updating IM in mid-January on progress.

Hudbay has previously evaluated particle sorting at its Snow Lake operations in Manitoba – with the benefits outlined in a desktop study “muted” given “bottlenecks and constraints”, Amelunxen said – but, at Constancia, it considered XRF sorting from the onset for copper-grade only pre-concentration, due to its perception that this application came with the lowest potential risk and highest probability of success.

The company has a three-phase evaluation process running to prove this, with phase one involving a “bulk sorting amenability study”, phase two moving up to laboratory-scale testing and phase three seeing trials in the field.

The “bulk sorting amenability study” looked at downhole grade heterogeneity to estimate curves of sortability versus unit volume, Amelunxen detailed. Laboratory testing of drill core samples to evaluate the sensor effectiveness was then carried out before an economic analysis and long-range-plan modelling was conducted.

With the concept and application of bulk sorting having cleared all these stage gates, Hudbay, in November, started pilot testing of XRF sensors on a loader. This involved fitting a ShovelSense unit onto the 19 cu.m bucket of a Cat 994H wheel loader, with around 20 small stockpiles of “known grades” loaded onto the bucket and dispatched into a feeder and sampling system (pictured below, credit: Engels Trejo, Manager Technical Services, Hudbay Peru). With this process completed, the company is now awaiting the results.

At a similar time, the company moved onto demonstration trials of a “production” ShovelSense sensor unit on the 27 cu.m bucket of a Hitachi ECX5600-6 shovel operating in one of the pits. It has collected the raw spectral data coming off this unit since the end of November, with plans to keep receiving and analysing sensor data through to next month.

“We should have the finalised XRF calibration in February, at which time we’ll process the raw data collected during the three-month trial period and compare it with the short-term mine plan (ie grades of ore shipped),” Amelunxen said. “So, by the end of February or early March, we’ll be able to validate or finetune the economic model.”

Should the results look favourable, Amelunxen is confident that leasing additional sensors and installing them on the other two Hitachi ECX5600-6 shovels will not take long.

Credit: Engels Trejo, Manager Technical Services, Hudbay Peru

“Plans may change somewhat as the program unfolds,” he said. “For example, we may have success sorting ore, but feel additional calibration is required for waste sorting at Pampacancha, in which case we may install production sensors on Constancia ores while doing another trial program at Pampacancha.

“It all depends on the precision of the XRF calibration.”

Higher head grades and potentially higher copper recoveries may be the headline benefits of using ore sorting technology, but Hudbay is equally focused on obtaining several key environmental benefits, including reduced consumption of energy and water.

On the latter, Amelunxen said: “This is expected due to the processing of less ‘waste’ by removing uneconomic material earlier in the process and reducing the hauling and processing costs of the uneconomic material.”

Looking even further forward – past a potential commercial implementation of XRF-based ore sorting at Constancia – the company plans to evaluate the application of other sensors, too.

“For our future development copper project in Arizona, we plan to look at other sensors as well,” Amelunxen said, referencing the company’s Rosemont asset.

This ore sorting project is not the only project the processing team at Constancia are examining, as Amelunxen already hinted at.

As part of the recovery uplift project, it is installing equipment that will allow the operation to increase the overall mass recovery of the roughers, which is currently constrained by the downstream pumps and cleaning circuit.

“This will allow us to achieve an expected 2-3% increase in copper recoveries without impacting concentrate grade,” Amelunxen said.

It has various initiatives underway under the “Moly plant improvement projects” banner, too. This includes flowsheet optimisation, pH control in the cleaners and pH reduction in the bulk cleaners.

“This project has been in the works since late 2019, and the new mechanical agitator installation in the cleaning cells was completed during the August 2021 schedule mill maintenance shutdown and the new nitrogen plant was commissioned in the second half of the year,” Amelunxen explained. “The next steps are pH control in the cleaners (with CO2), water balance optimisation and potentially installing a Jameson flotation cell as a pre-rougher (the cell is already on site and not in use, it will be repurposed pending results of the pH trials).”

A flotation reagent optimisation study is also on the cards, aimed at reducing zinc and lead contamination in the copper concentrate.

“A depressant addition system is on the way to site and should be installed in February, with plant trials commencing in March,” Amelunxen said, explaining that this followed laboratory test work completed in 2021.

New Gold to collaborate with MineSense in underground ore sorting move

Automation, Base metals, Comminution of minerals, Environmental, Mine operation news, Mineral processing, Mining equipment, Mining services, Mining software, Precious metals, Sustainable mining, , , , , , , , , , , , , , , , , ,

MineSense is gearing up for a move underground with the help of New Gold and its New Afton gold-copper mine in British Columbia, Canada.

The Vancouver-based technology company has already established and proven its ShovelSense technology for the open-pit mining sector, with its X-ray Fluorescence (XRF) sensor-based system now operating on shovels, wheel loaders and excavators on a commercial basis across six operating mines. This includes large installations at Teck’s Highland Valley and Copper Mountain’s copper operations in BC, as well as one ShovelSense unit at the Antamina copper operation in Peru.

Designed for operation in extreme environments and retrofits on any existing mobile equipment, ShovelSense units come equipped with a human machine interface and proprietary algorithms that measure and report ore grade/characteristics. They can also connect directly to fleet management or other existing control software systems, enabling mine operators to reconcile geological block models with actual ore grade data.

Having finetuned the system for above-ground operations, the company is now embarking on its underground move, according to MineSense President and CEO, Jeff More.

A trial of the underground ShovelSense system at New Gold’s New Afton mine is first up to complete product development. The company will be installing a unit on a Cat R1600G LHD for this step. This will be followed closely by installation at a “large entity” in Chile – with More anticipating start up in the September or December quarter.

The development agreement with New Gold at the BC-based mine is looking to trial and finetune the system for underground operations, with More confident the ShovelSense system will stand up to the test.

“The core technology – all of the algorithms, software, hardware – is the same as ShovelSense for open-pit mining,” More said. “It is the ‘application package’ – looking at how we can attach the unit to the machine and protect it in an underground environment – that is what we have to test out. The design for this is already complete; it’s just a matter of trialling it.”

New Afton represents a good test for the system.

New Afton is Canada’s only operating block cave mine, with the New Afton deposit part of a larger copper-gold porphyry district in the region. The operation regularly mines 15,000-16,000 t/d of ore and waste, with the majority of this currently going to the mill.

The company has already pursued “ore segregation” projects to boost the grade of material being fed through to the processing side, but the move into the higher-grade C-Zone in 2023-2029 will place an even greater emphasis on ore/waste boundaries and milled tonnes at the operation.

At the same time, the ShovelSense deployment at New Afton will represent the first time MineSense has sent a unit into a mine that has so much payable gold, with most operations the company has worked on being primarily base metal-oriented.

In 2020, New Afton produced 64,000 oz of the yellow metal, along with 32,659 t of the red metal.

“This will be the first time we’re touching gold at this level; we have other mines that have payable gold but not at that level,” More explained.

In New Afton’s case, sampling and historical data has proven that the orebody’s copper and gold ratios tend to be consistent and unchanging over the long term. With this knowledge, New Afton has used technology in the past to determine the copper value and make ore/waste production decisions. ShovelSense allows New Afton to move the ore/waste production decision to the drawpoint, according to MineSense. This reduces mixing and blending during the crushing and conveying circuit which can homogenise the material to the point where it is not worth segregating.

Trialling new technology such as this is nothing new for New Afton.

The operation already uses automated loading through Sandvik’s AutoMine solution, is employing electrification with the use of Sandvik and MacLean Engineering battery-powered mobile equipment, and, in the process plant, has Gekko Systems’ highest volume InLine Pressure Jig IPJ3500 to improve gravity concentration.

More says the ShovelSense unit could be in the Cat LHD bucket at New Afton in August, with the machine then going through an above-ground trial ahead of the underground transition at the end of September.

“By early Q4, we should have completed the pilot,” he said.

LKAB to trial AI-backed XRF drill core logging with help of Minalyze and Sentian

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LKAB, Minalyze AB and Sentian say they have joined forces in a consortium to develop the latest technology for scanning drill core.

In March 2020, LKAB started a test with the Minalyzer CS drill core scanner where the goal was to improve the workflow for core logging – ie how the results of exploration drilling are analysed. The test led to a permanent installation in Kiruna (Sweden) and expansion to Malmberget where data from the Minalyzer CS is used to help geological logging of the drill core.

The consortium of LKAB, Minalyze and Sentian are now set to take the use of data to the next level when boreholes in LKAB’s deposits are to be investigated. The new artificial intelligence application being developed by the trio will make the analysis much faster, with the time to evaluate a drill core reduced from weeks to minutes, with increased accuracy.

This could see Minalyze’s X-ray Fluorescence-backed CS scanner analyse LKAB drill core while leveraging Sentain’s industrial artificial intelligence solutions to make real-time decisions relating to drilling and exploration activities.

The technology development driven by the consortium will be a world first, changing the entire industry, the companies say.

Jan-Anders Perdahl, Specialist at LKAB’s Exploration Department, said: “With the collaboration, the core logging takes a big step through machine learning and artificial intelligence. The geologist can, at an early stage, place greater focus on the parts of the core that show chemical or other changes. Opportunities are opened up to gain increased knowledge about ore formation processes and alterations in a completely different way than before. One can also get indications that you are close to mineralisation and where it may be located, and thereby streamline exploration.”

The technological leap will give LKAB’s staff increased competence, increased quality in and efficiency of the work, as well as reduced need for other analysis methods, according to the companies.

Annelie Lundström, CEO of Minalyze AB, said: “We are at an interesting time when the hardware to extract consistently high-resolution data from drill cores is available and we can now take the next step and generate value from data together with our customers. In this collaboration, we will develop algorithms that can map rock layers in so-called lithological logs with very high confidence. This can only be done by combining expertise from all three parties.

“The results from our collaboration will forever change how drill core logging takes place everywhere and will result in a more efficient, non-subjective and consistent process.”

Martin Rugfelt, Sentian CEO, added: “We see great power in the application of modern artificial intelligence to data from the mining industry and there is major potential in further combining our machine learning technology with Minalyze’s unique capabilities in data collection and analysis.”

New Metso Outotec Courier on-stream analyser could reduce gold losses

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Metso Outotec is launching its next-generation Courier® 6G SL on-stream analyser for direct measurement of gold, platinum and other valuable metal concentrations from ore feed, concentrate, and tailings streams.

The new analyser enables accurate real-time elemental analysis measurement critical for establishing efficient process control to improve process stability and maximise recovery, it says.

It builds on the Outotec Courier 6X SL analyser with a more powerful X-ray tube and measurement channels optimised for direct on-line measurement of gold and other elements from calcium to uranium, the company says. This makes it particularly suitable for applications where gold is recovered with other metals such as silver or copper.

The system can measure up to 24 individual process streams – each with an individually adjustable measurement time – to ensure optimal measurement accuracy and sampling frequency in even the most complex polymetallic flotation circuits. It can also provide direct measurement of gold concentrations down to 0.2 g/t

The new next-generation on-stream analyser combines Wavelength Dispersive X-ray Fluorescence and Energy Dispersive X-ray Fluorescence technologies with a high-power X-ray tube for unparalleled measurement performance, Metso Outotec claims. It also features an automatic internal reference measurement for guaranteed stability under changing environmental conditions.

Lauri Veki, Metallurgist at Agnico Eagle’s Kittilä operation in Finland, said: “Agnico Eagle Kittilä has used the new on-stream analyser for flotation control and optimisation since October 2019. Measurement information provided by the Courier 6G SL has enabled more efficient control of the pre-flotation circuit and helped to reduce gold losses.”

Bruker brings benchtop EDXRF into lab automation space

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Among several new innovations Bruker has launched is a benchtop X-ray elemental analyser that, the company says, can speed up elemental analysis in mining applications and be integrated into automated laboratory environments.

Originally planned for a launch at the now delayed Analytica 2020, this week, Bruker has proceeded with an online launch of these new products.

The company says its next-generation benchtop energy dispersive X-ray Fluorescence (EDXRF) spectrometer, S2 PUMA™ Series 2, is equipped with HighSense™ technology for increases in throughput by about a factor of three times.

Bruker’s software, SPECTRA.ELEMENTS™, comes with enhanced features and faster algorithms, leading to circa-40% shorter evaluation times, the company said.

The S2 PUMA Series 2 supports elemental analysis applications from cement, steel, mining and petrochemical, to food analysis and pharma quality control, according to the company.

The benchtop EDXRF instrument is used for solid and liquid samples, prepared or bulk, for the elemental analysis from carbon to americium (C – Am), according to Bruker. “Detectable elemental concentrations in the samples can range from parts per million up to 100%,” it said.

Bruker continued: “The HighSense technology of the S2 PUMA Series 2 combines high-power (50 W), long-life-time X-ray tube with closely coupled optics and the HighSense detectors. The HighSense (for Na to Am) and HighSense LE detector (C-Am) are next generation silicon drift detectors with high count rates, superb energy resolution, and Peltier-cooling for shortest measurement times, excellent data quality and low operation costs

“The unique sample handling options of the S2 PUMA Series 2 make it the perfect fit for many applications in industry and research, where precise and accurate results must be delivered fast on an easy-to-operate instrument.”

Depending on sample type and desired throughput, the versions Single, XY Autochanger, Carousel, Automation, and Mapping-Stage are available, the company said.

And, according to Bruker, the S2 PUMA Series 2 Automation is the only benchtop EDXRF spectrometer ready for full integration into automated laboratory environments.

“The Mapping-Stage enables automated multi-spot analysis collected on small and large samples (up to 152 mm in diameter),” Bruker said.

De Beers diamond XRF technology optimises sorting at emerald mine

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De Beers Group Technology has adapted one of its X-ray fluorescence (XRF) diamond sorting range of machines to create “a secure and efficient sorting solution for emeralds”, it says.

According to De Beers Group Technology head, Gordon Taylor, the company’s sorting technologies have been applied to a range of minerals apart from diamonds, and these include gemstones like rubies to lower value commodities like manganese and coal.

“We are always on the look-out for new applications for our sorting equipment, which also employ X-ray luminescence, X-ray transmission, laser, magnetics and ultra-violet technologies,” Taylor said.

“So, we were excited by the opportunity to collaborate with Magnum Mining and Exploration on their Gravelotte emerald project in Limpopo province.”

In its trial mining and processing phase, Gravelotte has been gathering data to confirm the historic grades previously recovered at the project. In operation for much of the 20th century, total recorded production from this area was estimated at nearly 113 Mct. It was reportedly the world’s largest emerald mine of its type in the 1960s, employing over 400 sorters, De Beers said.

General Manager of Operations at Gravelotte, Wessel Marais, said the traditional manual method of sorting carried an associated security risk and led to less than optimal recoveries.

“Various mechanical sorting options are available on the market today,” Marais said, “and Magnum approached De Beers Group Technology to determine whether their diamond sorting technology could be adapted to emerald sorting.”

He says testing of samples provided by Magnum came out with successful results.

“This led to Magnum leasing an XRF machine from De Beers Group Technology for the duration of our trial mining, and the results to date have been very encouraging,” he says. “With the machines now deployed in the operational environment, research and development work is continuing in conjunction with De Beers Group Technology to refine the process.”

Taylor noted that constructive collaboration with customers is often an important element in extending the application of De Beers Group Technology’s equipment.

“On this project, we were able to conduct some fundamental investigation on the properties of emeralds to guide us in developing the most effective solution,” he said.

The De Beers Group Technology emerald sorting machine can make a potentially significant contribution to the success of the Gravelotte operation, according to De Beers, with its high recoveries combined with excellent processing security. The project aims to reach a target of around 3 Mct/y as its initial production rate.

Before the run-of-mine material reaches the De Beers Group Technology XRF machine, it is crushed to -30 mm and put through a trommel screen for cleaning and further size reduction. After material containing emeralds is ejected from the material stream by the sorter, it is further sorted by hand and graded.

“De Beers Group Technology is constantly pushing the boundaries where our equipment can be applied and has had significant successes in non-diamond commodities. Whether removing the value product or the waste from the process stream, our sorting technologies can be the game-changer in the viability of many projects,” Taylor concluded.

XRF ore sorting shows potential at Yukon zinc project

Base metals, Comminution of minerals, Metallurgy, Mineral exploration, Mineral processing, Mineral project development, Mining equipment, Mining project news, Mining services, Precious metals, , , , , , , , ,

X-ray fluorescence (XRF) ore sorting technology has found another fan after Fireweed Zinc reported positive results from preconcentration test work at its Macmillan Pass zinc project in the Yukon of Canada.

Samples from Macmillan Pass’ Boundary Zone, a discrete bulk-tonnage, exploration target 15 km northwest of the Jason zinc-lead-silver deposit, were put through XRF, X-ray transmission, electromagnetic and dense media separation sorting tests by Canada’s Sacré-Davey Engineering at the University of British Columbia, with XRF showing the most promising results, Fireweed said.

The principal results of the 436 rock samples tested in the XRF trials included the potential to upgrade the feed grade from 2.5% Zn to 5% Zn and a rejection rate of 70-50%, with zinc recoveries ranging from 80-85%.

Fireweed pointed out that the analysis in the study assumed that 25% of the feed had fines (-12 mm) which cannot be processed in the ore sorter. As a result of this, the fines would bypass the sorter and combine with the ore sorter product, with the final grade of 5% Zn achieved after combining the ore sorter product with the fines assumed to have a grade of 2.5% Zn.

XRF sorting is currently used at over 50 operations across the world, including Hecla Mining’s San Sebastian mine, in Mexico, and Anglo American’s Mogalakwena mine, in South Africa, according to Fireweed.

Typically, it uses an XRF sensor to distinguish and measure surface metal abundances on rock pieces moving on an enclosed conveyor belt unit. The XRF readings for each individual rock are then analysed by high speed software to distinguish and flag rocks with metal values above and below a set threshold.

At the end of the conveyor belt, focused high pressure air jets or mechanical levers then separate the designated higher-grade rock pieces for processing and reject low grade and waste pieces. The amenability to ore sorting depends on the material characteristics of a deposit.

Fireweed said: “The Boundary Zone samples responded positively to XRF testing because zinc values on the surfaces of individual rock pieces correlate closely with the overall zinc assays of those rocks.”

Fireweed Zinc CEO, Brandon Macdonald, said the ore sorting results imply there is potential to improve the economics of the Macmillan Pass project.

He continued: “These results suggest that we may be able to reject 50% to 70% of low-grade and waste rock at low cost near a potential open-pit operation at Boundary with less than 15% loss of zinc mineralisation before material is transported to a central processing plant at Tom.”

Macdonald said the company has now moved the drill to Boundary to both confirm and step out from historic holes, as well as obtain a 2 t sample to confirm these ore sorting results may be obtained on a larger scale.

“If the larger test is successful, we can then incorporate the benefits of an XRF ore sorting system at Boundary into a revised preliminary economic assessment economic study along with upgraded information from recent drilling at Tom, Jason and End Zones.”

A 2018 preliminary economic assessment at Macmillan Pass showed that a 4,900 t/d operation could be constructed for an initial capital C$404 million ($305.9 million) using starter-pits on the Tom West and Jason Main zones.

This plan would result in average yearly contained-metal production of 85,000 t of zinc, 48,000 t of lead and 2 Moz of silver over an 18-year life, with an after-tax net present value (8% discount) of C$448 million generated.