Tag Archives: XRT

Vast sees path forward at Manaila with help of TOMRA’s XRT ore sorting solution

Vast Resources says it is continuing to evaluate the recommencement of production at its Manaila polymetallic mine in Romania and, as part of this process, has been working with TOMRA to assess the suitability of X-ray Transmission (XRT) ore sorting technology to optimise the mine’s production profile.

The assessment has demonstrated, to date, that by installing an XRT machine at the plant to pre concentrate ore at the pit, the technology would be highly effective for three main reasons:

  • A reduction in transportation costs as improved mass reduction would significantly reduce the material being transported from the mine to the processing plant;
  • A reduction in processing costs due to reducing the throughput at the plant; and
  • Higher-grade product being delivered to the plant.

It is anticipated that processing and transportation costs could be reduced by up to 55%, according to Vast.

“This cost reduction could have a dramatic impact on the mine’s financial performance,” the company says.

Samples from both types of mineralisation at Manaila, massive sulphide and disseminated sulphide, were sent to the TOMRA Test Centre in Wedel, Germany, to ascertain improved mass reduction and grade upgrade potential. Both mineralisation types showed amenability to the XRT process with metal content recovery on the massive sulphides at 95.4% for copper, 93.6% for lead and 95.2% for zinc in 71% of the mass, the company explains. The disseminated sulphides returned a metal content recovery of 84.2% for copper, 67.2% for lead and 84.4% for zinc in 35% of the mass.

The combined results show that 93.1% of copper, 82.2% of lead and 92.4% of zinc metal could be recovered in 45% of the mass when mining the polymetallic ore on a ratio of three tonnes disseminated sulphide to one tonne of massive sulphide, being the typical historical ratio of mining at Manaila.

Andrew Prelea, Chief Executive Officer of the Vast Resources, says: “These results clearly underpin our view that Manaila is economically viable, and the management team are considering various mine plan scenarios of bringing Manaila back into production.”

The 138.6 ha Manaila-Carlibaba exploration licence contains a JORC 2012 compliant measured and indicated resource of 3.6 Mt at 0.93% Cu, 0.29% Pb, 0.63% Zn, 0.23 g/t Au and 24.9 g/t Ag with inferred resources of 1 Mt at 1.1% Cu, 0.4% Pb, 0.84% Zn, 0.24 g/t Au and 29.2 g/t Ag. Comprising the Manaila polymetallic mine (currently on care and maintenance) and the Carlibaba extension project, Vast intends to establish a larger mining and processing facility at Manaila-Carlibaba which would eliminate the need for costly road transport of mined ore to the existing processing facility located at Iacobeni, around 30 km away.

Preliminary studies by the company indicate the potential for a new open-pit mine to exploit mineral resources to a depth of some 125 m below surface, and to simultaneously develop a smaller higher-grade underground mine below the open-pit mineral resources.

TOMRA XRT ore sorting test work delivers the goods at Kutcho’s copper-zinc project

Higher head grades and recoveries, a reduction in run-of-mine material reporting to the milling and flotation circuit, a smaller tailings management facility, and lower power and water demand are just some of the benefits to have come out of ore sorting test work at Kutcho Copper’s copper-zinc project in British Columbia, Canada.

Recent bulk sample test work was conducted to determine the effectiveness of using ore sorting technology from TOMRA Sorting Mining to improve the processed grade and reduce the mill feed tonnage of mineral resources at the project.

ABH Engineering Inc and TOMRA were commissioned to undertake this work to establish the amenability of Kutcho’s Main and Esso deposits to ore sorting using an X-ray Transmission (XRT) sensor. Two phases of test work, including a representative 0.75 t bulk sample derived from drill core, were undertaken at TOMRA Sorting Mining in Germany under the supervision of ABH Engineering.

“The ore sorting process helps concentrate the metals of commercial interest from the Kutcho deposit, which are principally associated with high density sulphide minerals,” Kutcho explained. “Rocks are individually scanned, and low grade (low density) waste material is selectively diverted away from downstream processing using compressed air jets. Preliminary test work on the sensitivity of the ore to a XRF sensor was also undertaken.”

The bulk sample tests conducted on a production-scale XRT ore sorter indicate that approximately 17% of the ROM material will be <12.5 mm in size and would therefore bypass the ore sorter and report directly to the milling and flotation circuit. Of the >12.5 mm feed, some 15% of the material reporting to the ore sorter was detected by the XRT sensors as being low grade or waste and will be rejected by the ore sorter, thereby reducing run-of-mine material reporting to the milling and flotation circuit by 13%. The overall recovery of metal (copper, zinc, silver and gold) reporting to the ore sorter is in the order of 99% (ie less than 1% of the metals of interest will be rejected by the ore sorter), Kutcho said.

Pre-sorting of the run-of-mine material by the ore sorter has the potential to reduce milling and flotation operating costs corresponding with the 13% rejection of low-grade material, it says. The commensurate increase in the head grade of the ore reporting to the flotation circuit has the potential to also result in improved metallurgical recoveries in the flotation circuit.

Additionally, it is anticipated that potential savings in capital and operating costs related to the smaller milling and flotation circuit will offset the costs associated with the ore sorter, according to the company. Savings will also be achieved by a reduction in the size of the tailings management facility. The optimally sized ore sorter reject waste material could be used as cemented rock backfill in the underground mines at both the Main and Esso deposits, resulting in further potential cost savings, Kutcho said.

Environmental benefits accruing to the project because of the introduction of ore sorting technology include a lower power and water demand, and a smaller tailings management facility, the company concluded.

Earlier this month, Kutcho said in a feasibility study progress report that it was considering open-pit mining for the majority of the Main deposit at Kutcho, allowing the company to capitalise on the high-grade, near-surface mineralisation, resulting in lower operating costs than underground mining. The remainder of the Main deposit and all the Esso deposit will continue to be evaluated assuming underground extraction by longitudinal longhole open stoping, it said.

The ore sorting test work was also being incorporated into the feasibility study design.

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 completes the diamond recovery loop with new XRT solution

TOMRA Sorting Mining says it is breaking new ground with a “unique” X-ray Transmission (XRT) Final Recovery solution that guarantees 99% diamond recovery.

With the new introduction, TOMRA is the first company in the industry able to supply a full diamond recovery solution using XRT technology from 2-100 mm, coupled with all the benefits of cloud computing for monitoring and managing the entire process, it said.

The new TOMRA COM XRT 300/FR final recovery sorter delivers concentration factors of up to one million with limited stages and is the only solution on the market that guarantees more than 99% diamond recovery, according to the company.

“The new sorter stands out for the high sorting efficiencies, the high diamond-by-weight concentrate, and the benefits deriving from its focus on a single consistent detection principal, diamonds,” the company said. “With this new introduction, TOMRA offers a complete partnered diamond recovery ecosystem with a flowsheet covering the entire process – from concentration to final recovery and sort house – and includes custom development with the end-user all the way to installation, then continued management of the asset and support with specialised services and training.”

The TOMRA COM XRT 300/FR is the latest step in TOMRA’s long-term diamond sector strategy, Geoffrey Madderson, Diamond Segment Manager for TOMRA Sorting Mining.

“We always had this clear objective, but the technology just didn’t exist,” he said. “We knew that to achieve our goal, we would need extremely advanced sensor technology. We have been working in-house on the development the new ultra-high resolution sensor more than five years, and now we are able to close the loop: the COM XRT 300/FR is the last piece within our recovery process, covering the final recovery and sort house applications to produce an ultra-high diamond-by-weight concentrate.”

TOMRA says its holistic approach and unique offering has earned a strong market trust in its XRT technology. As a result, the first three TOMRA COM XRT 300/FR sorters produced have already been sold to customers, all of whom purchased the machines on the back of their experience of previous TOMRA sorters.

The makeup of the TOMRA COM XRT 300/FR sorters sees input material evenly fed via a vibration feeder onto a conveyor belt. An electric X-ray tube creates a broad-band radiation, which penetrates the material and provides spectral absorption information. This is measured with an X-ray camera using DUOLINE® sensor technology, which focuses on a single, constant property of the material, density, it explained.

The advanced ultra-high resolution sensor information is processed and analysed by our TOMRA’s new Image Processing Pipeline to provide a detailed “density image” of the material, allowing it to be separated into high- and low-density fractions. If diamonds are detected, it commands the control unit to open the appropriate valves of the ejection module at the end of the conveyor belt. The detected diamonds are separated from the material flow by jets of compressed air. The sorted material is divided into two fractions in the separation chamber.

The tight tolerances and accurate alignment of the new ultra-high resolution sensor results in a high-quality picture that ensures a clear discrimination between diamonds and low-density materials down to 2 mm, according to TOMRA. The sorter features high-speed valves with a fine nozzle pitch, which significantly reduces non-diamond material in the concentrate. The result is ultra-high diamond-by-weight concentrate with a guaranteed recovery of more than 99%, the company claims.

It is possible to replace multiple sorting stages with a single TOMRA COM XRT 300/FR sorter all the way down to hand sorting, according to the company. In the final recovery application, the sorter targets the highest tonnage through the sorter that can be achieved with the highest recovery efficiency, which ranges from five tonnes to one tonne. As a result, the operation benefits from a smaller footprint and achieves much better grade.

It is also possible to replace hand sorting with a TOMRA COM XRT 300/FR. In a sort house application, it targets the highest diamond-by-weight concentrate possible, with about half the tonnage than final recovery, bringing multiple benefits. It removes the traditional bottlenecks around hand sorting efficiencies and eliminates the human error factor, the company says. In addition, it provides a high level of security by protecting the product from human intervention.

TOMRA’s partnered diamond recovery ecosystem includes consultation services during the development of the system and throughout the lifecycle of the equipment, support running the sorters, and help with specialised services and training. The company has also leveraged digital technologies to provide effective support, through its Virtual Demonstration and Test Solution and features such as the TOMRA Visual Assist Augmented Reality tool for remote assistance.

“With TOMRA, the customer’s entire recovery system falls into one ecosystem,” explains Madderson. “This allows for better compatibility and interconnectivity between the different applications of the recovery process. It gives our customers the full benefit of using cloud computing through our TOMRA Insight platform, which turns our sorters into connected machines. This enables customers to monitor and manage their recovery process in one easy-to-access place for both on-site and off-site management teams.”

TOMRA has set up a showroom dedicated to demonstrations of the TOMRA COM XRT 300/FR sorter at its Test Center in Wedel, Germany. Later in the year, TOMRA will also offer virtual demonstrations for those unable to travel to the Test Center.

Vast Resources to leverage new equipment and XRT ore sorting at Baita Plai

Vast Resources has devised a new mechanised mine plan for its Baita Plai polymetallic mine in Romania that will see mining capacity increase by 65% and ore sorting employed to increase mill feed grades.

The new mine plan includes the acquisition of three LHDs (including at least one narrow-vein electric LHD), an Aramine face jumbo drill rig, two Resemin Muki 22 long hole drilling rigs and a TOMRA X-ray Transmission (XRT) ore sorter.

Execution risk is expected to be significantly reduced compared with the old labour-intensive plan through the employment of senior international staff; the use of increased mechanisation; and the fact that shortly, with the expediated development plan now possible through the new equipment, the mining areas will be in areas newly drilled by the company and not in less stable old mining areas, the company said.

The company, in co-operation with TOMRA Mining, has concluded an initial investigation on ore from Baita Plai as part of the development of the new mining and processing plan. The objective of the work was to determine the amenability of ore from Baita Plai to be pre-concentrated using TOMRA sensor-based sorting technologies to produce a high-grade pre-concentrate, pre-milling feed.

“The study showed a clear amenability for the ore to be separated using TOMRA’s advanced XRT technology to identify both massive mineralisations, as well as fine mineral inclusions, using its proprietary combination detection algorithms to produce a high-grade pre-concentrate and eliminate non-grade containing waste material,” the company said.

The XRT implementation and processing plant upgrades are set to be completed by December 2021, the company said, with mill feed grades expected to be concentrated by 1.25-1.75 times. This would see the sensor-based sorter shift 60% of tonnage into the accept stream for the mill and 40% into the reject stream, with a 92% yield in the accept tonnage.

The new mine plan presents a cost reduction of 21% in dollars per mined tonne with an operational efficiency of 63 tonnes per total employee costed (TEC) at steady state, versus the previous plan efficiency metric of 43 tonnes per TEC, Vast Resources said. It also sees mining capacity rise to 22,000 t/mth, from 13,300 t/mth.

Andrew Prelea, Chief Executive Officer of Vast Resources, said: “This is a robust and comprehensive mine plan which has been developed using rigorous technical parameters. On behalf of the board, I believe the plan set out to shareholders today represents a benchmark for us to deliver on over the coming years in tandem with our broader expansion plans at Baita Plai and across our wider portfolio.”

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.”

Lucara recovers second plus-300 ct diamond of 2021 at Karowe mine

Lucara Diamond Corp has announced another recovery of significance from its 100% owned Karowe Mine, in Botswana, with its TOMRA X-ray Transmission (XRT) sensor-based ore sorting units, again, helping the miner recover and keep the diamond intact.

A magnificent unbroken Type IIa 378 ct gem quality top white diamond was recently recovered from milling of ore sourced from the M/PK(S) unit of the South Lobe, Lucara reported. This recovery is the second plus-300 ct gem quality diamond to be recovered this year from direct milling of the M/PK(S) unit, a further testament to the strong resource and process circuit performance at Karowe, the company said.

Both the 378 ct and the 341 ct diamonds recovered this year came from the Coarse XRT circuit, Lucara said.

Eira Thomas, Lucara’s CEO, said: “The 378 ct joins a rare and special lineage of exceptional, high value diamonds recovered at Karowe and continues to highlight the wonderful diamond potential of Botswana. Continued and consistent recovery of large diamonds, such as the 378 ct and 341 ct stones, comes at a critical time and provides continued strength and additional foundation to the opportunity to finance and build the underground expansion at Karowe that will see mining continue for at least another 13 years after the open pit ceases operations in 2026.

“We look forward to a safe, productive and busy 2021.”

A 2019 feasibility study looking at a combined open pit and underground future at Karowe showed the company could double the mine life of the operation for $514 million in pre-production capital by developing an underground deposit.

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.”