Tag Archives: x-ray transmission

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.”

TOMRA Mining’s ore sorting solution helps Renison tin mine do ‘more with less’

TOMRA Mining and its X-ray Transmission (XRT) technology has, the company says, provided an effective solution for the extreme conditions at the Bluestone Mines Tasmania JV (BMTJV) Renison tin mine in Tasmania, Australia, with sensor-based ore sorting solution unlocking significant value and delivering environmental benefits.

The Renison mine is 50% owned by Metals X through the BMTJV, and is the only major tin mine in production in Australia with a mining rate of close to 1 Mt/y, according to TOMRA. While slated capacity is 1 Mt/y, the concentrator is restricted to 750,000 t/y.

The mine’s extreme humidity and highly acidic processing water (pH around 4.5) create unique challenges for the sorting process, the equipment and waste management, according to TOMRA.

A complex flowsheet

The underground mine operates a primary crushing system before the material is transported to the surface through a shaft. Once there, it enters the pre-concentration plant, where it undergoes a three-stage crushing, screening and cleaning process. The particles are split into two fractions – 10-25 mm and 25-60 mm – which are fed into two TOMRA XRT sorters. The output consists of two streams: the product, which is transferred to the wet plant, and the waste, which is fed into a TOMRA EM sorter to separate acid-forming sulphides from this waste stream.

In the wet plant, the product goes through primary grinding followed by bulk sulphide flotation. The tailings are processed downstream to concentrate the cassiterite tin mineral through gravity concentration; gravity tails are further treated via desliming and tin flotation. The combined concentrates are fed to a leaching circuit to remove carbonate minerals. After a final wash stage, the concentrate is de-watered and dispatched.

BMTJV approached TOMRA to address two key requirements at the plant. The first was the need to upgrade the tin feed to the plant, as Ben Wraith, Principal Project Metallurgist at BMTJV (pictured below), explained: “The Renison tin operation wanted to achieve economies of scale, putting more tonnes through the front end of the plant without upgrading the back end downstream – we wanted to do more with less.”

The second requirement was to address the environmental issue of removing acid-forming sulphides from the waste.

Following site visits and extensive discussions with BMTJV’s teams, TOMRA proposed a solution that addressed the tin feed quality with two COM Tertiary XRT 1200 sorters and the waste issue with a COM Tertiary EM 1200 sorter. A team from BMTJV visited the TOMRA Test Center in Sydney, Australia, where they observed what the XRT sorter operating at capacity is capable of.

Gavin Rech, Technical Manager at TOMRA, said: “Our XRT stands out for the high spatial and density resolution and its ability to do contrast sorting, identifying fine high-density tin inclusions in the ore with an accuracy that has no equal on the market. On top of that, it can separate it from the acid-forming sulphides, so that we have the ability of pulling the tin into the first product and sending the rest to the EM sorter.”

Gavin Rech, Technical Manager at TOMRA

The two COM Tertiary XRT 1200 sorters went into operation in 2018. Initially, BMTJV’s strategy focused on low reject grades, devoting less focus to achieving the mass reject rate and overall process plant throughput. However, the specific conditions at the Renison mine affected the results achieved. The large variance in run of mine (ROM) particle size distribution resulted in insufficient stability in the feed to the circuit. In addition, the extremely wet conditions in west Tasmania and consequent high ambient moisture content, combined with the high moisture of the ore delivered from underground, further affected the sorting process.

In 2019, a new investigation was conducted into the ore sorting performance and led to a change of direction, where the operation shifted away from targeting low reject grades, towards sorting as aggressively as possible, according to Wraith, moving from a “tin recovery-based” operating strategy to a “mass reduction” one.

“We are getting 20-25% mass reduction, so 75-80% of the materials are going into the wet plant, and we are still achieving 97-98% tin recovery overall across the crushing circuit,” he said. “Pre-concentration didn’t materially impact overall recovery because the tin in the material that is rejected as waste is extremely fine grained and a proportion is associated with sulphides, so it wouldn’t have been fully recovered in the downstream wet plant and would have been lost to tailings.”

This approach, he said, is best for Bluestone’s application as it provides the ability to process 15-20% more tin units without having to upgrade the downstream concentrator.

Wraith added: “Operating the sorting circuit has slightly increased our overall processing cost, but this is more than offset by the large increase in ROM throughput by 15-20% and, thus, tin production, so the unit cost per tonne of tin produced is reduced by almost 10%. We’ve broken multiple production records in the last year in tin units, and this gives us confidence in what we can achieve because the machine performs over and over again if you treat it right and if you prepare your feed correctly.”

TOMRA XRT success leads to upgrade decision

In view of the results achieved with the two TOMRA XRT sorters, BMTJV decided to upgrade the ore sorting circuit with two new, recently launched XRT models with stainless steel internal parts and advanced features such as the TOMRA ACT user interface and the TOMRA Insight cloud-based platform, according to TOMRA.

“The decision to buy new machines was easy,” Wraith said. “The stainless steel will assist prolonging the TOMRA sorter’s life by protecting the unit from our high-moisture and corrosive environment. The more ergonomic design will help our maintenance teams, which is particularly important for machinery operating in these harsh conditions.”

Wraith said the use of TOMRA Insight, the ore sorting company’s subscription-based service that relays and analyses machine data, will “enhance everybody’s understanding and experience of the machines”.

He added: “It will be more of an analytical platform for our metallurgy and maintenance staff, providing ample opportunity to gain valuable information that can be analysed and optimised over time. The one feature I am personally interested in is the particle size monitoring through the machines, which will enhance our overall circuit performance because we have an integrated circuit with the crushing and screening plant. Feed preparation is key to maintain a consistent performance – knowing how well you’re preparing your feed in a live fashion can only end up with a better result.”

TOMRA will also be able to log into the machine and check the daily reports generated by TOMRA Insight, so its technical teams will be prepared ahead of site visits for maintenance or optimisation.

Wraith concluded: “TOMRA has been working with the site maintenance team to tailor solutions to our operating environment, which has been invaluable. TOMRA supported me through site visits, which included equipment inspections, site-based training of our personnel, and an openness to continually improving the technology and finetune it to our site-specific requirements. They assisted the site with troubleshooting, optimisation, discussing the nuts and bolts of the issues as they arose, and finding a solution that works.”

Bartram comes back to TOMRA Mining ready for sensor-based sorting demand uptick

Having left TOMRA Mining more than a decade ago only to return to the Germany-based company in November, Kai Bartram’s re-arrival at the sensor-based sorting firm represents a good time to take stock and reflect on how far the mining sector has come with its understanding and acceptance of this type of pre-concentration technology.

Bartram, now Global Sales Director of TOMRA Mining and a member of TOMRA’s Mining Management Team, was happy to answer some of IM’s questions after getting his feet back under the table in the company’s offices in Wedel, Germany.

IM: How has the mining industry’s appreciation of the benefits of sensor-based ore sorting changed since you left TOMRA in 2010? What trends have led to a wider take up of the technology?

KB: In 2010, sensor-based sorting (SBS) was still seen as a niche technology in the mining industry. Some smaller, more innovative mining companies had seen the potential and effectively implemented SBS, but the mining industry, as such, had not accepted the technology. While in the industrial minerals sector several optical sorters – and, in the diamond industry, mainly X-ray luminescence machines – were operating, the rest of the industry was cautious about integrating sorters into their flowsheets.

That changed slowly with the introduction of Dual Energy X-ray technology. The technology is so robust and perfectly suited to the harsh environment of the mining industry that the economic benefits of pre-concentration became obvious. Another point that has strongly supported the adoption of sorting technology is the fact that average ore grades keep decreasing while energy costs keep increasing.

IM: Diamond and industrial mineral operations were typically the first adopters in the mining sector; what commodity sectors do you expect to see dominate demand for sensor-based ore sorting systems into 2030? What changes to the technology or wider industry understanding have led to this belief?

KB: In the beginning, sorters were seen as small machines, which would never meet the capacity requirements of large hard-rock mineral processing circuits. Therefore, only small mines saw the opportunity to implement sorting as a pre-concentration step in their process. Today, we see that our 2.4-m-wide flagship sorter, TOMRA COM XRT 2.0, can process up to 500 t/h, so that large operations can also implement the technology. An example of such a trend is the Ma’aden Phosphate Umm Wu’al processing plant, where 2,000 t/h are processed with TOMRA XRT sorters.

I am sure we will see more of these bigger projects in many different commodities. Of course, the current market trend is towards ores that are required for the electric revolution, like lithium, copper, cobalt and rare earth elements. TOMRA has proven that we have the right solution to upgrade those ores efficiently and can contribute to more economical output. So, I expect to see more installations in the future.

The TOMRA COM XRT 2.0 units can process up to 500 t/h

IM: Are there any regions more willing to apply these solutions than others? Why is this the case?

KB: If you look at our global reference list, you can see that the larger installed base resides in Europe, Africa and the Americas. The Asian markets are a little behind, but this is easily explained by history. As a European company, we focused more on the better known and established markets. In general, the mining market is a very global industry with big players active in all continents.
I do not believe there are regions more willing to apply the technology than others. It is just a matter of supporting all regions in the same way. TOMRA is investing heavily to ensure we have a good global support network, to be there for and with our clients.

IM: Do you expect to see more collaboration with OEMs over the next decade when it comes to implementing ore sorting solutions with process flowsheets? How do you see the input of both TOMRA and OEMs benefitting the wider mining industry?

KB: Collaboration is essential in any industry. We need specialists who are experts in their field, and TOMRA is one of the global leaders in sensor-based sorting. In order to achieve the best results in one field, one must focus. Therefore, big projects can only be undertaken by a group of companies or experts who collaboratively work together. We, as a solution provider, are very dependent on well-engineered and integrated plant designs and believe we have to collaborate and have close relationships with plant builders to ensure the best possible solution for our clients.

Southern Innovation set for exploration scanning, ore sensing growth with Russell appointment

Southern Innovation, a developer and manufacturer of state-of-the-art real-time materials analysis equipment for the global mining industry, says it has taken a strategic step forward in sales and marketing with the appointment of Steve Russell as Head of Sales and Business Development.

Russell, currently Director of Mining at Scott Automation & Robotics, joins the Southern Innovation team in mid-January 2022 in a role that is expected to drive growth in the company’s key areas of rig-mounted exploration scanners and conveyor-mounted ore sensing/scanning, especially in bulk ores, and looking to near-term applications in base and precious metals.

An engineering professional with a strong background in mining as well as sales and marketing, Russell has previously driven several step-change innovation and automation strategies in the mining industry, according to Southern Innovation.

Southern Innovation, Managing Director David Scoullar, said this appointment will drive strategic growth that has been in the planning stage for a considerable time.

“Southern Innovation has a solid and conservative business base, built off a unique foundation of robust, patient and home-grown development of much-sought-after signal processing technology,” he said. “We have worked closely with some of the most respected and sizeable international mining companies in R&D, and we are now confidently transitioning to grow product sales.

“Our clear objective is to help our customers to improve productivity as well as reduce waste in minerals identification, extraction and processing as the industry drives to net zero emissions by 2050.”

Southern Innovation’s key proprietary products are known as DrillScan™ and GradeScan™.

DrillScan (pictured above, working in the Pilbara of Western Australia) was developed in close collaboration with BHP and is an X-ray Transmission scanner that bolts onto the drill chain of RC drill rigs, performing accurate and continuous analysis while drilling. Results from field use demonstrate more than 95% correlation between continuous, real-time analysis and post-drilling XRF lab-based grade analysis of contemporaneous samples, according to the company.

GradeScan™, meanwhile, is an online, real-time conveyor-mounted X-ray scanner capable of characterising sampled bulk ore in real time at 1 mm resolution across multiple dimensions, according to the company. It features full spectrum scanning, enabled by Southern Innovation’s patented digital signal processing technology, SITORO® Accelerated Analysis.

Steinert XRT ore sorter testing shows promise at Northern Minerals rare earth project

Northern Minerals Ltd has progressed its ore sorting project enhancement initiative with the commissioning and testing of the Steinert sorter system, and is now producing ore sorted material and converting this to a 30% total rare earth oxide (TREO) concentrate in its’ Browns Range beneficiation plant in Western Australia.

Northern Minerals’ CEO, Mark Tory, said: “The construction, commissioning and testing of the ore sorter circuit marks another milestone in the development of the Browns Range project.

“The positive bulk sample tests confirm the effectiveness of the ore sorting circuit on the Wolverine ore to significantly increase the head grade to the mill which is expected to result in higher production rates and lower operating costs for a full-scale operation at Browns Range.

“It’s also pleasing to see the initial ore sorting tests the Banshee ore showing promise which, if shown to be effective in future tests, has potential to significantly increase the Browns Range mineral resource estimate.”

He added: “Being able to test and operate the ore sorting circuit in conjunction with the pilot beneficiation plant is providing extremely valuable data that you just can’t get from small bench-scale tests and this will feed into our feasibility study for a potential commercial scale heavy rare earth operation at Browns Range.”

The ore sorter system was constructed during 2020 and 2021 and commissioned in June 2021. The sorter that was installed is a 2-m wide Steinert sorter that uses X-ray Transmission (XRT) and laser detectors to identify rare earth mineralisation.

The sorter has been run over two test campaigns, which included 41 test runs processing 5,300 t of ore from the run of mine stockpiles largely coming from Wolverine ore, and five test runs on Banshee ore that was bulk sampled from a surface costean that provided 285 t of Banshee ore.

The tests have confirmed that simultaneous sorting of two size fractions is possible on the sorter, allowing a single machine to sort both sortable size fractions (10 mm-25 mm and 25 mm-75 mm), Northern Minerals says. The sortable fraction (>10 mm material) of Wolverine ore can be successfully sorted (90% TREO recovery in 50% of the mass) and, when combined with non-sortable fines, achieves a 45% grade increase to the mill and over 95% TREO recovery when feeding a 0.9% TREO ore.

The sorter system is now being run to produce feed for the beneficiation plant and 4,479 t of Wolverine ore have been processed through the ore sorter circuit to the end of August. Processing of the Wolverine ore sorted material in the beneficiation plant has resulted in better recoveries in the magnetic separation plant and flotation plant compared with feeding unsorted ore, the company says. A bulk sample of 50 t of 30% TREO rare earth concentrate has being produced for test work by facilities identified with likely future capability and capacity to process the heavy rare earth xenotime concentrate produced at Browns Range.

Bulks sample tests have highlighted some key factors to consider for ore sorting that cannot be determined at bench scale using vendor equipment in laboratory settings. Understanding the impact of these factors is critical to including an ore sorting circuit in a full-scale processing facility.

Initial sorting tests of the Banshee ore have shown that the highly oxidised surface material contains a large fines fraction and that the grade of the sortable fraction (ie >10 mm) can be doubled recovering more than 60% of the TREO in 25% of the mass. An additional bulk sample is being extracted from deeper in the costean and three diamond drill holes are being drilled for further test work.

The bulk ore sorting test work is a key input for the full-scale beneficiation plant feasibility study currently underway, which will also leverage off the substantial technical, operational and economic data from the R&D test work at the Browns Range Pilot Plant since 2018, the company says.

Wescoal after RoM upgrade with Acrux, IMS Engineering XRT ore sorting solution

Acrux Sorting Technology has announced that its advanced sensor-based sorting technology is to be deployed at a Wescoal Holdings Ltd-owned coal mining operation in South Africa.

Acrux subsidiary, Acrux Sorting Coal (ASC), has signed a coal beneficiation agreement with two wholly owned subsidiaries of Wescoal, whereby ASC will deploy advanced sensor-based sorting technology to upgrade lower-grade coal from the mines.

Under the agreement, ASC will provide a fully funded turnkey crushing, screening and sensor-based sorting solution centred around advance dual-energy X-ray Transmission (XRT) unit to process run of mine (RoM) coal.

The plant is to be designed, constructed, commissioned, operated and maintained by IMS Engineering Limited, Acrux’s partner on such ore sorting projects. IMS Engineering is a subsidiary of Germany-based HAZEMAG & EPR GmbH.

ASC’s sorting solution offers significant economic benefits as coal resources can now be upgraded to be included as a saleable product, which will reposition the mines along the cost curve, it said.

Paul Bracher, Managing Director of IMS, said: “The XRT technology has proven its ability to upgrade RoM coal through rejecting material that has sulphur or ash content that exceeds programmed parameters.”

The solution will also have a positive environmental impact as no water is used during beneficiation, and the carbon footprint is reduced through the optimisation of transportation and materials handling.

Wescoal’s Executive Director, Thivha Tshithavhane, said: “This sorting technology solution will enable us to impact on ESG, while creating shareholder value from optimising our coal resources at no capital investment.”

Sean Browne, ASC’s Chairman and Group Founder, added: “Partnering with Wescoal underlines our commitment to driving sustainable innovations that reduce the environmental impact of mining.”

TOMRA boosts sensor-based ore sorting process with key updates

TOMRA Sorting Mining has introduced the TOMRA ACT user interface together with a new image processing pipeline and additional process data for TOMRA Insight, all of which will, the company says, enable improvements in the overall sorting process for greater productivity and profitability.

The new TOMRA ACT graphical user interface (UI) brings a fundamental change in the way customers interact with their machines, making it easy to control the work flow in their sorting process with simple, intuitive touch gestures and actions on the screen, according to the company.

The UI provides sorting information and real-time process data at a glance through easy-to-understand graphics. With this clear information, the operator can better monitor the sorting process and make fast adjustments at any time, the company claims. The quick feedback on machine performance and throughput enables them to optimise the process, maximising productivity and efficiency.

Ines Hartwig, TOMRA Product Manager

Ines Hartwig, TOMRA Product Manager, explained: “Throughout the development process of TOMRA ACT, we conducted many in-depth discussions with our customers to ensure we provided them with an interface that would improve the performance of their sorters, benefitting their business. We have been testing it with customers and the feedback has been very positive; in particular about the ease of use, even remotely, which facilitates controlling the process and adjusting settings.

“With the new interface, customers interact with their sorters in a much more intuitive way and they have better guidance on how to improve the overall handling of the sorters. As a result, they will be able to improve the productivity of their sorting plant and the profitability of their mining operation.”

TOMRA is introducing the new UI on all its current X-ray Transmission (XRT) sorters and is planning to extend it to other machines in its offering at a later stage. Upgrade packages to retrofit previous models of its XRT sorters will also become available.

The new Image Processing Pipeline, meanwhile, analyses the data sent by the sorter’s sensors and cameras. This solution provides TOMRA with even more flexibility to adjust and customise the image calculations according to the application and the customer’s specific requirements to achieve the best possible sorting results.

The enhanced image processing solution also collects detailed process data, such as information on particle size distribution of the feed, belt occupancy for insights on feed tonnages, or data relating to the health of the sorter. All these statistics are fed to TOMRA Insight, the cloud-based data platform, adding to the process information it has already received. TOMRA said: “This enables customers to improve the overall sorting process further, taking fast action when changes occur in upstream equipment or in the material’s composition. They are able to better monitor and control their processes, the feed material and the sorted fractions, improving their profitability.”

The new enhanced Image Processing Pipeline, and additional data fed to TOMRA Insight, have already been introduced on TOMRA XRT sorters and will in the future be extended to other products.

Peel Mining’s South Cobar preliminary flowsheet to factor in ore sorting

Peel Mining says positive results from ore sorting test work at the Southern Nights and Mallee Bull deposits, part of its 100%-owned South Cobar Project, in western New South Wales, Australia, provide encouragement for the inclusion of this pre-concentration technology into future process plant design.

So encouraged by this testing is Peel that it has engaged GR Engineering to integrate ore sorting technology into an updated processing plant technical report for the project.

At the same time as this, Peel announced that GR Engineering had recently completed a preliminary process plant technical report for South Cobar that considers crushing, grinding, gravity, flotation and cyanidation process stages for the recovery of gold, silver, copper, lead and zinc from the various mineralisation styles within Peel’s deposits.

Meanwhile, the recently received positive preliminary ore sorting test work results from work undertaken on diamond drilling samples shows there is potential for improvements in the flowsheet.

The ore sorting test work, completed in conjunction with ongoing metallurgical studies, was undertaken by Steinert and TOMRA.

Steinert ’s test work on Southern Nights mineralisation demonstrated strong recovery and upgrade potential with two size range samples returning, on average, circa-93% Zn, circa-91% Pb, circa-91% Ag, circa-87% Cu and circa-82% Au recoveries to an average of circa-54% of the feed mass (circa-46% of feed mass rejection) increasing the lead and zinc grades by 61% and 64%, respectively.

TOMRA’s test work on Mallee Bull mineralisation achieved significant waste mass reductions while maintaining very high copper recoveries (≥95% for the higher-grade breccia copper and massive sulphide copper samples), the company said. A lower grade breccia copper sample upgraded from 0.59% Cu to 1.05% Cu with 77% Cu recovery and 56% mass rejection, it noted.

“Positive results from ore sorting at Southern Nights and Mallee Bull deposits provide encouragement for the inclusion of this pre-concentration technology into future process plant design and, as a result, Peel has engaged GR Engineering to integrate ore sorting technology into an updated processing plant technical report,” the company said.

Peel’s Executive Director of Mining, Jim Simpson, said: “The completion of the processing plant technical report by mineral processing solutions experts GR Engineering is a critical first step in understanding the potential composition of the milling infrastructure required for the company’s development plans.

“The detail presented in the report by GR is impressive and the report will form the basis for ongoing preliminary studies for the refinement and improvement of the processing plant design as new information comes to hand.

“We are also very pleased with the potential of ore sorting as part of any future South Cobar project hub’s processing route with initial test work pointing to the amenability of both Southern Nights and Mallee Bull mineralisation to separation using 3D-XRT ore-sorting technology, allowing for the simultaneous rejection of barren or waste material whilst retaining the bulk of contained metal, and in the process, upgrading the value of the ore.”

Simpson added: “Apart from reducing the overall feed mass by the rejection of waste at early stage, other benefits of ore sorting include potentially upgrading lower-grade mineralisation and reducing the size of the processing plant offering potentially reduced capital, power, water and tailings storage needs.”

TOMRA XRT units help recover unbroken 998 ct diamond at Lucara’s Karowe mine

TOMRA’s COM XRT 2.0/1200 ore sorters have aided Lucara Diamond’s Karowe diamond operations, in Botswana, once again, recovering an unbroken 998 ct high white clivage diamond from the 100%-owned mine.

The diamond, measuring 67 x 49 x 45 mm, was recovered from direct milling of ore sourced from the EM/PK(S) unit of the South Lobe, and follows a series of significant diamond recoveries during this recent production run, including several top quality clivage and gem-quality stones of 273 ct, 105 ct, 83 ct, 73 ct, and 69 ct in weight.

“The EM/PK(S) forms an important economic driver for the proposed underground mine at Karowe and continues to produce large gem-quality diamonds in line with expectations, a further testament to the strong resource performance at Karowe,” the company said.

Last year, a feasibility study showed the company could double the mine life of Karowe by establishing an underground mine for $514 million in pre-production capital.

The 998 ct diamond (pictured) was recovered in the MDR (Mega Diamond Recovery) XRT circuit that allows for diamond recovery post primary crushing and prior to milling. The MDR circuit has, in the past, treated material in the size range between 50-120 mm. This latest recovery represents the second plus-500 ct diamond recovered from this circuit in 2020, Lucara noted.

Year to date, Karowe has produced 31 diamonds greater than 100 ct, including 10 diamonds greater than 200 ct comprising of the 549 ct Sethunya, and the 998 ct diamond.

Eira Thomas, Lucara CEO, said: “Lucara is extremely pleased with the continued recovery of large high-quality diamonds from the South Lobe of the Karowe mine. To recover two plus-500 ct diamonds in 10 months along with the many other high-quality diamonds across all the size ranges is a testament to the unique aspect of the resource at Karowe and the mine’s ability to recover these large and rare diamonds.

“Operations at Karowe have continued through 2020 and operational challenges, due to COVID-19 restrictions, have been met with professionalism by the team. We look forward to a safe finish to 2020 and continued success at Karowe as we remain focussed on strong operations to ensure maximum resource performance.”

Rafaella considers processing options after positive TOMRA XRT ore sorting tests

Sensor-based ore sorting test work from TOMRA Sorting Solutions has shown the potential for lowering the planned capital expenditure and operating costs associated with developing the Santa Comba tungsten-tin project in Galicia, Spain, project owner Rafaella Resources has reported.

The “exceptional” ore sorting results showed a 50% rejection of un-mineralised rock and an approximate doubling of feed grade, which would significantly lower the planned process capex and opex, and enhance process efficiency through a simpler process flowsheet, the company said. The 50% cut in process tonnage also reduces the project’s environmental impact, with a far lower volume of waste generated, lower energy consumption per unit of metal produced and reduced water consumption.

The “Grade Recovery Curve” showed the potential for over 90% tungsten recovery with an increased yield of up to 55% of feed mass, it added, while testing of the low-grade ores showed viable recovery from over 2 Mt of mineralisation not currently factored into the project’s economics.

The program tested two bulk samples selected from assayed drill core crushed to two size groups: +8 mm to -20mm and +20 mm to -40 mm. Sample No. 40 was circa-1,100 kg of average grade ore at 0.15% WO3, while Sample No. 41 was circa-250 kg of low-grade ore at 0.05% WO3.

TOMRA’s conclusion in its report was that “the results from this test work were positive for both sizes and samples. Significant upgrades of WO3, as well as high recoveries, were achieved in all test runs for sample ‘40’ using X-ray Transmission (XRT), while leaving rather low grades for WO3 in the waste fraction. A calculation has shown that a 90% recovery of tungsten can be possible at a waste removal of more than 50%.

“The low-grade sample ’41’ could be upgraded by a factor of 1.7 to 3. For further calculations, a waste grade between 0.025 and 0.030 is achievable.”

The success of the XRT sorting tests allows several mining and process options, Rafaella says, including:

  • Simplification of the process;
  • Bulk ore zone mining to reduce operational costs and maximise ore recovery;
  • In-pit sorting and conveying;
  • Bulk underground mining and sorting of wider ore zones using larger and longer stopes;
  • Separate sorting of sub-grade mineralisation; and
  • Sorting of satellite deposit ores prior to hauling to the process plant.

TOMRA estimates a throughput of 1 Mt/y of feed ore and circa-500,000 t/y of pre-concentrate would require two XRT units.

Rafaella’s Managing Director, Steven Turner, said the results from the ore sorting test work have exceeded the company’s expectations.

“The clear discrimination between ore-bearing rock and low grade or barren rock has delivered high recoveries and yields allowing for a simpler process plant,” he said. “The benefits of this simplification will be significant once the metallurgical studies are completed. These results are now being fed into the feasibility study that is in the final stages of completion.

“The company looks forward to providing the market with these exciting updates on the fast tracking of its flagship project over the coming weeks.”

Santa Comba is a brownfield project with a 5.1 Mt JORC 2012 compliant near-surface inferred resource at 0.203% WO3 and 0.014% Sn and an underground inferred resource of 234,000 t at 0.95% WO3 and 0.28% Sn.