Tag Archives: XRF

Anglo American Platinum’s modernisation drive to continue into 2021

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Anglo American Platinum says it is looking to deliver the next phase of value to its stakeholders after reporting record EBITDA for 2020 in the face of COVID-19-related disruption.

The miner, majority-owned by Anglo American, saw production drop 14% year-on-year in 2020 to 3.8 Moz (on a 100% basis) due to COVID-related stoppages. Despite this, a higher basket price for its platinum group metals saw EBITDA jump 39% to R41.6 billion ($2.8 billion) for the year.

As all its mines are now back to their full operating rates, the company was confident enough to state PGM metal in concentrate production should rise to 4.2-4.6 Moz in 2021.

Part of its pledge to deliver more value to stakeholders was related to turning 100% of its operations into fully modernised and mechanised mines by 2030. At the end of 2020, the company said 88% of its mines could be classified as fully modernised and mechanised.

There were some operational bright spots during 2020 the company flagged.

At Mogalakwena – very much the company’s flagship operation – Anglo Platinum said the South Africa mine continued its journey to deliver best-in-class performance through its P101 program.

Rope-shovel performance improved to 26 Mt in 2020, from 15 Mt in 2019, while drill penetration rates for big rigs increased from 15 m/h, to 16.7 m/h. Alongside this, the company said its Komatsu 930E truck fleet performance improved to 298 t/load in 2020, from 292 t/load in 2019.

These were contributing factors to concentrator recoveries increasing by two percentage points in 2020 over 2019.

During the next few years, the company has big plans to further improve Mogalakwena’s performance.

In 2020, the mine invested R500 million in operating and capital expenditure, which included commissioning a full-scale bulk ore sorting plant, coarse particle rejection project and development of the hydrogen-powered fuel-cell mining haul-truck (otherwise referred to as the FCEV haul truck).

First motion of the 291 t FCEV haul truck is still on track for the second half of 2021, with the company planning to roll out circa-40 such trucks from 2024.

Anglo Platinum said the bulk sorting plant (which includes a Prompt Gamma Neutron Activation Analysis and XRF sensor-based setup, pictured) campaign at the Mogalakwena operation is due to end this quarter.

The company’s hydraulic dry stacking project is only just getting started.

This project, which involves coarse gangue rejection before primary flotation for safer tailings storage facilities, is expected to see a construction start in the June quarter, followed by a campaign commencement and conclusion in the September quarter and December quarters, respectively.

On another of Anglo Platinum’s big technology breakthrough projects – coarse particle rejection for post primary milling rejection of coarse gangue before primary flotation – the company plans to start a campaign in the December quarter of this year and conclude said campaign by the end of the March quarter of 2022.

The company also has eyes on making progress underground at Mogalakwena, with a hard-rock cutting project to “increase stoping productivity and safety” set for Phase A early access works this year. This project is set to involve swarm robotics for autonomous, 24/7 self-learning underground mining, the company said.

Lastly, the company’s said the digital operational planning part of its VOXEL digital platform had gone live at Mogalakwena. VOXEL is expected to eventually connect assets, processes, and people in a new digital thread across the value chain to create a family of digital twins of the entire mining environment, the company says. Development is currently ongoing.

Looking back to 2020 performance at the Unki mine, in Zimbabwe, Anglo reflected on some more technology initiatives related to R26 million of expenditure for a digitalisation program. This included installing underground Wi-Fi infrastructure, as well as a fleet data management system to track analytics on primary production equipment. The company says these digital developments will enhance real-time data analysis, improve short-interval control and overall equipment effectiveness.

To step up mechanisation of its PGM operations at Amandelbult, Anglo American Platinum is also investing in innovation.

This includes in-stope safety technologies such as split panel layouts to allow buffer times between cycles, creating safer continuous operation and reduced employee exposure; improved roof support technology and new drilling technologies; a shift to emulsion blasting from throw blasting; and safety enhancements through fall of ground indicators, 2 t safety nets, LED lights, and winch proximity detection.

Meanwhile, at the company’s Mototolo/Der Brochen operations, it is working on developing the first lined tailings storage facility at Mareesburg in South Africa to ensure zero contamination of ground water. The three-phase approach adopted for construction of this facility will be completed this year.

CRC ORE simplifies complexity for value

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“There are a lot more variables to bulk ore sorting than just the technology,” Jon Rutter says.

The Principal Geologist of the Cooperative Research Centre for Optimising Resource Extraction (CRC ORE), Rutter knows his stuff. He has worked underground in both narrow-vein and mass-mining operations, as well as at large scale open-pit mines; in the base and precious metal arena.

During a presentation at International Mining Events’ IPCC Virtual event in early-February, he shared a slice of this knowledge while reviewing a recent installation project CRC ORE had been involved in at a platinum group element (PGE) operation.

“The intrinsic value of bulk ore sorting comes from the delivered heterogeneity,” Rutter said. “We have got to be able to sense and divert a higher-value pod of material versus an adjacent pod of lower-grade material on a conveyor.

“You essentially want to put more material into the mill that adds value – and not what destroys value.”

Looking at the wider bulk sorting opportunity in mining, Rutter explained the sensor diversion units (SDU) in bulk ore sorting were smaller than what the mine itself can typically offer in the form of a selective mining unit (SMU), which may be comprised of a dig block totalling around 15,000 t.

A truck offers a 100-300 t opportunity, while a shovel typically comes with a 50-100 t opportunity.

Even with a modest conveyor running at a 2,000 t/h rate, an on-board sensor (eg PGNAA or PFTNA) running at a 30 second integration time (the time to analyse one grade) would provide an SDU of 16.7 t. A sensor with lower integration time (eg XRF at 10 seconds) comes in at 5.6 t.

The ability to provide analysis down to this level has enticed several major companies into testing bulk ore sorting solutions.

Anglo American has trialled bulk ore sorting solutions at copper and platinum group metal mines, while BHP recently engaged CRC ORE to examine deployment of cutting-edge preconcentration techniques under its Grade Engineering® platform at the Olympic Dam mine, in South Australia.

The SDU with bulk sorting may be that much smaller than the SMU of a typical mine plan, but lab-level precision is not required for these solutions to work, according to Rutter.

“What I need is the ability to measure the metal content adequately,” he said. “When I say adequate, this incorporates the entire error bar of the system. That system includes the inherent geology, the mineralisation style and heterogeneity. We also need to consider the precision, accuracy and integration time – which is the technology constraint; but we also need to include the weightometers, the flop gates, the diversion gates, as well as that entire mining and materials handling process right from the start – from blasting, loading, hauling and dumping to the plant.

“But for bulk ore sorting what I end up requiring from this combined data is usually a binary decision: am I above or below a certain threshold?”

He expands on the bulk ore sorting (BOS) assessment process: “The other way of looking at this is simply considering it as planned ore loss and dilution. If we go back into that dig block, in that 15,000 t of material, I’ve already incorporated planned ore loss and dilution decisions or parameters into that SMU decision. So, if we look at bulk ore sorting, I am just talking about those different attributes – the error bars of a BOS system – as the inputs or parameters for BOS planned ore loss and dilution – it’s now just at a smaller and more precise opportunity.”

The company took a two-phase approach to the BOS opportunity at the PGE operation in question.

The first phase involved carrying out heterogeneity analysis of the orebody; correlation analysis of PGEs to base metals; selection of sensor technologies (XRF and PGNAA were selected in this case), design, layout and equipment selection for the bulk ore sorting plant; natural deportment analysis of the orebody; development of a preliminary business case; the ore type selection and sampling strategy; and project planning and management.

CRC ORE and the company in question settled on a solution where a Caterpillar 992 wheel loader dropped material off to a system using a combination of grizzly, feeder, sizer, conveyors, diverter, stackers and associated equipment from MMD, used in conjunction with an ore sensing system equipped with both PGNAA and XRF sensors to continuously measure the elemental composition. The PGNAA sensor provided a “penetrative” analysis calculation whereas XRF provided a “surface” sensing calculation, Rutter explained.

An incline conveyor ahead of the diverter gate and the accept/reject stream provided the 30 second integration time the PGNAA analyser required.

Phase two of the project involved online and offline (pre-install) work; sensor calibration; proving the technology; and proving the technology can drive physical separation.

Rutter said the completion of static calibration of the sensors saw the PGNAA sensor 20-30% calibrated, and the XRF sensor 70-80% calibrated.

This outcome harked back to Rutter’s assertion that “bulk ore sorting implementation is not a plug and play opportunity”.

A dynamic calibration in online mode completed under normal conditions was required to get the PGNAA sensor up to speed. This process, meanwhile, solidified the operation of the XRF sensor.

While the two sensors were calibrated in different ways, Rutter showed data that confirmed both were in unison when it came to reading the ore/waste that came through the conveyor (see right-hand graph below).

“The two sensors are independent of each other and fundamentally very different, but they can work well together, or separately,” he said.

CRC ORE was able to prove the technology by running the same sample through the circuit a number of times, as Rutter explained: “We fed 15-20 t of run of mine material into the hopper and repeated the process 15 times, putting the same 15-20 t sample through the system. We could then start to determine the precision and accuracy of the sensors and the system.”

For further verification, the sample was crushed, sub sampled and assayed.

“We wanted a binary response to ore and waste to build confidence,” Rutter added.

Phase three involved the ramp up to production scale, going from, say, 500 t/h to 1,000 t/h; carrying out validation by campaign; and finally integrating with the operation.

There were several lessons all mining companies – and bulk sorting vendors – should keep in mind from such a project, Rutter said.

Operations need to assess the impact of mixing across the entire materials and mining handling process as soon as possible, for one.

“The earlier we can put this data into the system, the better,” Rutter said. “Without a heterogeneity signature, we cannot implement bulk ore sorting.”

He also stressed the importance of timely feedback. Sensor calibration, a secondary crushing/sampling plant and assaying were all required to build confidence in the solution.

Rutter added: “The proper calibration of sensors does require a considerable and ongoing effort…but that is no different from any other process plant or equipment.”

Operators also need to be wary of where they set these solutions up in mines, recognising this heterogeneity dynamic.

“Bulk ore sorting is quite unlikely to be universally suited to the entire deposit,” Rutter said. “The analogue for this is a flotation plant; there are ore types in the mine where you achieve better performance in the flotation plant and others where you get worse performance.”

Hitachi XRF analysers to help Tanzanian Mining Commission with mineral verification process

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Twenty four of Hitachi High-Tech Analytical Science’s handheld X-ray Fluorescence (XRF) X-MET8000 Geo Expert analysers have been supplied to the Tanzanian Mining Commission, based in Dodoma, to help officials ensure correct analysis of minerals for value determination before they are exported

The delivery, through Hitachi High-Tech exclusive Africa distributor, United Scientific (Pty) Ltd, based in South Africa, will help the commission enfoce new measures for exporting minerals where mineral values need to be controlled and verified before they are exported out of the country.

Mining is one of the leading sectors in Tanzania and exports of minerals such as gold, silver, copper and nickel, are increasing each year as demand for these precious metals grows.

The 24 X-MET8000 Geo Experts bought by the Tanzanian Mining Commission will be used by the officials in the laboratory as well as in mineral and gem houses established throughout the country to verify local ore concentrations prior to export. They will also help to verify that correct value on clearing declaration documentation has been provided before minerals leave the country at various border posts.

Hitachi High-Tech’s instruments were chosen by the Tanzanian Mining Commission due to the robustness, reliability, cloud storage capabilities and flexible package options available for the X-MET8000 Expert Geo as well as the service form its local distributor, Hitachi says.

The package includes rare earth elements and precious metals methods to ensure full visibility. The X-MET8000 Expert Geo can analyse rare earth elements including Y, Sc, La, Ce, Pr and Nd in addition to other common elements explored from mines and soils, according to the company.

Jacques Le Roux, Managing Director of United Scientific South Africa, said: “We are delighted to be working with the Tanzanian Mining Commission and local inspectors. We look forward to continuing to build our strong partnership and work very closely together. Over the last three years, United Scientific and Hitachi have supplied record numbers of handheld instruments into the African market making us the leading handheld analyser provider in the region.”

Paul Bunting, VP Sales and Service EMEA, said: “The X-MET8000 Expert Geo offers excellent accuracy, speed and limits of detection in a rugged IP54 and MIL-STD-810G format that’s affordable. Our delivery of the 24 X-MET8000 handheld XRF analysers to the Tanzanian Mining Commission as a preferred vendor is yet another example of Hitachi helping businesses unlock the power of analysis and striving to increase social value.”

MineSense, Commerce Resources look at ore sorting options for Ashram REE project

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Commerce Resources has started a test project initiative with MineSense as part of its ongoing collaboration with CanmetMINING.

The project with Commerce will include assessing the spectral response on 127 course analytical rejects from drill core, comprising five rock types associated with the Ashram rare earth and fluorspar deposit, in Quebec, Canada.

Of these 127 rejects, a total of 72 are from drill core within the Ashram deposit’s primary mineralised zone: the A-Zone. Based on the information collected, MineSense will be able to assess the laboratory-scale efficacy of its technology to the Ashram deposit material. If successful, a value contribution assessment may be completed as a follow up activity for the Ashram project.

MineSense specialises in digital technology solutions for ore-waste classification in real time at the mining stage (run of mine), thereby providing better grade control compared with that of the deposit block model or mine plan. It uses data analytics, combined with its trademarked ShovelSense and BeltSense technologies, to monitor mineralogical or grade changes in an orebody daily, as it is mined. This information allows for optimal ore blending, grade trend characterisation, and overall improved mine planning with resultant cost efficiencies.

The MineSense technology is based on X-ray Fluorescence sensors fitted to specific pieces of mining equipment to monitor the spectral response of the material being actively mined. The technology provides for a higher level of control compared with the typical ore sorting process which occurs at the truck scale in the process plant, Commerce says.

One of the standout deployments of ShovelSense is at Teck Resources’ Highland Valley Copper (HVC) operations in British Columbia.

The funding for the test work at Ashram is provided by Natural Resources Canada through CanmetMINING’s six-year rare earth element (REE) and chromite program (announced in April 2015), focused on developing new extraction technologies, addressing Canadian environmental challenges, and improving the knowledge of Canadian deposits, Commerce says. The company’s contribution to the collaboration is a supply of REE mineralised material from Ashram, in which several tonnes remain readily available from a bulk sample completed in 2012.

The Ashram deposit outcrops at surface, allowing for cost-effective collection of material for test work. As such, the company is actively engaging with various research and academic institutions to support the advancement of the rare earth element industry in Canada, and in Quebec specifically, it said.

The resource base at Ashram consists of 1.59 Mt of material averaging 1.77% total rare earth oxides (TREO) in the measured category, 27.67 Mt at 1.9% TREO in the indicated category and 219.8 Mt at 1.88% TREO in the inferred category. The preliminary economic assessment outlined a 4,000 t/d open-pit operation with a 0.19:1 (waste:ore) strip ratio over a 25-year mine life. Annual production averaged circa-16,850 t of REO over the life of mine.

Steinert to bolster sorting system test capacity in Pulheim

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Steinert is to introduce additional sorting lines for mining and waste recycling at its new test and development centre in Pulheim, Germany, the company says.

The new lines are being installed in an effort to better achieve the company’s aspiration of “test before you buy”, allowing it to “respond with ever more accuracy to the sorting aims of extraction, purity and profitability for each sorting task”, Steinert said.

Steinert’s sorting solutions are used throughout the mining industry as a way of pre-concentrating material ahead of milling.

The metal sorting line of the new test and development centre will official go into operation on September 22. This milestone will be marked with a virtual event held on that day.

By opening the new building, the company is trebling its testing capacity, allowing it to be more flexible in responding to customer demands, it said.

“The processing sequence deployed in the sorting systems is the same as that used in a real industrial plant,” Peter Funke, CEO of the Steinert Group, said. “We are delighted that even more customers can try out our technology, from magnetic separators to sensor-based sorting systems, such as X-ray transmission, X-ray fluorescence and near-infrared (NIR),”

The research and development team is also moving to the same building in Pulheim, seven kilometres away from STEINERT’s headquarters in Cologne, allowing customers to derive even more benefits from the latest developments, the company said.

Olympus adds to handheld XRF range with Vanta Element-S

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Olympus has added to its line of handheld X-ray Fluorescence (XRF) analysers for fast light element detection with the Vanta Element-S XRF instrument.

The new unit delivers fast light element detection at an affordable price, joining a family of cost-effective, entry-level Vanta Element XRF instruments, the company says.

The S model is equipped with a silicon drift detector (SDD) to analyse light elements like magnesium (Mg), aluminum (Al), silicon (Si), sulphur (S) and phosphorus (P) in alloys.

Ideal for precious metals, the Vanta Element-S effectively measures ferrous metals, aluminum, copper, stainless steel, nickel and gold carats, it said. “The analyser offers clear on-screen grade ID and comparison for the light elements Mg, Al and Si in seconds.”

For greater uptime and reliability, the analysers are IP54 rated to resist dust and moisture and built to pass a 1.2 m drop test (MIL-STD-810G). Other protective features include a stainless-steel faceplate and a Prolene® window with Kapton® mesh support that sticks on and peels off for toolless window changes in the field, the company said. The analysers, the company says, continuously perform in temperatures from -10°C to +45°C.

“Vanta Element-S analysers come with the essential features the Vanta™ series is known for: speed, reliability, ruggedness, connectivity and smartphone-like ease of use,” the company said. Weighing 1.32 kg, the analyser is up to the challenge of all-day testing for alloy and metal analysis. “Powered by Olympus’ proven Axon Technology™, the S model brings the same high-count rate and stability as the rest of the Vanta series for fast results and return on investment.”

Optional wireless connectivity, meanwhile, helps future-proof the analyser for Industry 4.0, the company says.

“Connect to the Olympus Scientific Cloud™ for wireless data sharing and access to convenient fleet management tools, as well as the Olympus mobile app or your network,” Olympus said. “The analyser also has a one GB microSD™ card to store results and two USB ports to easily export data. For added flexibility, the analyser is compatible with accessories like the Vanta field stand, soil foot, probe shield and holster.”

Olympus will be hosting a webinar titled, ‘Innovative applications of portable X-ray diffraction (pXRD) and X-ray fluorescence (pXRF) for base metals and gold exploration’ later this week. To find out more click here.

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

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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.

CSIRO and Gekko’s OLGA receiving good reception at Queensland gold mine

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Field trials for the CSIRO-developed Online Gold Analyser (OLGA) are showing such positive results at a Queensland gold mine that the technology is expected to be ready for market this year, the research organisation reported recently.

OLGA is an X-ray fluorescence-based technology capable of detecting gold in slurry with around 1,000-times better accuracy than conventional methods – and in real time, according to CSIRO.#

The analyser, which will be available through technology and services company Gekko Systems, detects gold (and other elements) contained in a continuous process stream.

OLGA can detect gold in slurries at 10 parts per billion using a pair of X-ray lenses that greatly magnify the slurry’s fluorescent gold signal as it passes through a tank.

“Normally you take samples from a stream and send that sample to a laboratory,” CSIRO Research Group Leader, Yves Van Haarlem, said. “If you’re lucky the lab is onsite, but even then the turnaround time for analysis can be 10 to 12 hours. That’s probably too late to do something about it. With OLGA you can act on what you’re seeing almost immediately.”

Conventional X-ray Fluorescence is already a well-known tool in the base metals industry for the monitoring and control of concentration plants, but they tend to have less accurate detection limits – usually in the tens to hundreds of parts-per-million (ppm) range, precluding their use in precious metal concentrators, according to CSIRO.

Richard Goldberg, Gekko’s Head of Innovation and Collaboration, said that other means of detecting gold have been lacking in accuracy and/or the timely availability of results. “We’ve never had the ability to directly monitor gold flows through a plant in real time before,” Dr Goldberg said. “We know that gold grade can vary over relatively short periods and that it will do so between the samples taken as part of traditional process control regimes. As the results from those samples are also delayed, they are unlikely to accurately reflect the changes occurring in the process stream.”

Dr Goldberg said OLGA’s value stems from its ability to provide important information in near real time. In effect, the operators of a plant will no longer be blind to changes in its performance, according to CSIRO.

Andrew Dixon, Gekko’s Performance Consultant Manager, said the new system is proving its triple bottom line credentials. Economically OLGA allows the processing plant to be controlled to allow maximum efficiency of gold recovery, he said.

“This has environmental benefits as well. It will allow you to optimise reagent additions and to reduce any emissions from the plant that may have to be detoxified or treated to be made safe,” he said.

This means a plant will end up with less reagent chemicals in the tailings.

“It’s also more sustainable – the efficiency improvements will have an effect on the stability of the operation,” Dixon said. “A more stable gold processing operation is always going to be more efficient.”

Dr Goldberg said the reaction from gold mining companies that have seen OLGA work in laboratory conditions has been extremely positive and have seen considerable interest in the technology.

“We’re currently conducting field trials to ensure it’s a solid product before we fully release it to the market. To date, the trials have been extremely positive,” he said.

Dr Van Haarlem said Gekko has been the ideal partner for CSIRO on this technology. “Gekko engineered the whole structure around the analyser so that the slurry can be easily analysed, validation samples can easily be taken, and to provide the robustness required for plant installation,” he said.

OLGA is not just about detecting gold concentration. It’s about providing information, according to CSIRO.

“You could, for instance, put OLGA on the feed stream and one on the tailings,” Dr Van Haarlem said. “You could then look at what went in and what went out. If there’s too much gold in the tailings compared to the feed then the plant knows immediately that it’s losing gold. All this can then be acted upon.”

Dr Goldberg said there has been interest from potential buyers from as far away as Africa, Europe and South America. A fully supported product should be available for these regions later this year, CSIRO said.

Dr Van Haarlem said the X-ray optic system is now being tested on platinum and can be used for other metals. Its application could be much more widespread, such as for detecting toxic elements in food and water.

Yet, he believes OLGA’s future rests in its potential to revolutionise gold processing plant strategies and to refine logistics.

“It will provide a lot of data on real time gold and slurry density, which can then be correlated with other plant parameters,” he said. “It might turn out that if you don’t mill the ore sufficiently, gold recovery suffers. It’s going to show us correlations we didn’t even know were happening. This information can help us to optimise the entire production circuit.”