Tag Archives: Lucara Diamond corp

UMS to start pre-sinking work at Lucara’s Karowe Underground Expansion project

Lucara Diamond Corp’s Karowe Underground Expansion project (UGP) in Botswana is moving ahead with mobilisation of shaft sinking teams commencing late in June, and pre-sinking activities scheduled in the September quarter.

The Karowe UGP, which is expected to extend the operation’s mine life to 2040, is in a fully-financed position, with the latest schedule expected to see underground production hit full production by the end of 2026.

The 2019 feasibility study for the project envisaged life of mine production of 7.8 Mct, a payback period of 2.8 years and an after-tax NPV (5% discount) of $718 million; all from $514 million in pre-production capital.

COVID-19 delays have pushed the project off the original schedule – both in terms of timeline and cost – but the company says it is now making headway towards a 2026 start to underground production.

Lucara said no “material variances” between the 2019 feasibility study and the current execution plan have resulted, despite the delays.

“Rather, during this period in 2020 and 2021, all critical path items were addressed and a concerted effort was placed on detailed design, engineering and procurement which have helped to significantly de-risk the project,” it said.

Out of the total capital budget, the company has spent $51.4 million on project execution activities through 2020 until the end of June 2021, including shaft and geotechnical engineering, procurement of long lead time and essential shaft sinking items, surface infrastructure and construction activities, bulk power supply power line engineering and procurement.

Mobilisation of the shaft pre-sink team has commenced with shaft pre-sinking on track to commence in the middle of the current quarter.

Detailed engineering and design of the underground infrastructure and layouts will commence this quarter and are expected to be competed in the September quarter of 2022, with no major changes from the 2019 study plan anticipated.

Underground mine development is scheduled to commence in the second half of 2024 with underground production ramp up starting in 2026. Full production is scheduled for the end of 2026.

At the same time, open-pit mining operations have been adjusted to limit the risk of production shortfalls during the ramp up of the underground mine operations commencing in the first half of 2026. The open-pit mine is expected to terminate in mid-2026, Lucara said.

Access to the underground mine will be via two vertical shafts, the production and ventilation shafts. The shafts will be concrete lined with the production shaft acting as the main air intake and the ventilation shaft as the exhaust.

The number of shaft stations and nominal elevations remain the same as the feasibility study, with the planned depth of the production shaft still at around 767 m. The final planned depth of the ventilation shaft has, however, increased marginally to 733 m, from 716 m.

A 7,200 t/d shaft operation using long hole shrinkage (LHS) mining will provide an additional 13 years of mine life to the Karowe operation after a five-year construction period. The 767-m-deep production shaft will be equipped with two 21 t skips for production hoisting and a service cage for man and material movement through the mine. This shaft will also serve as the main fresh air intake to the mine.

The pre-sink construction contract and shaft sinking equipment procurement were awarded to UMS Botswana and UMS South Africa, respectively. METS International Ltd, a subsidiary of UMS, was awarded the shaft engineering contract.

The company explained: “Detailed design and engineering work on the production and ventilation shafts is now 90% complete, and has resulted in the following changes to the 2019 feasibility study: i) production shaft diameter has increased from 8 m to 8.5 m, ii) ventilation shaft permanent headframe, hoists and internal conveyances have been removed, iii) parallel pre-sinking of both shafts, iv) ventilation fans and coolers to be located on surface, v) in-shaft grouting of water strikes changed from grout curtain installation from surface, vi) planned development of an additional sublevel to assist in drilling of drawbells, and vii) removal of 670L de-watering galleries.”

Increased schedule time related to shaft sinking has been a result of the increased production shaft diameter, time allowances for in-shaft grouting during sinking operations planned at known water strike horizons, holing through all shaft stations between shafts and additional ground support for underground stations/level breakouts, the company said.

UMS is in the process of mobilising crews to Karowe to initiate pre-sink works. Pre-sinking of the two shafts will run in parallel and start with mobile cranes and then transition to Scott Derrick cranes with the final depth of pre-sink at around 40 m below surface.

With the exception of an additional sublevel (340L) to assist with drill and blast of drawbells, the design, layout and infrastructure of the underground mine all remain aligned with the 2019 feasibility study, the company noted.

Temporary power for shaft sinking is required until such time as the upgrade bulk power supply infrastructure is commissioned in the December quarter of 2022. A three-phased ramp up of the generator capacity is planned to support the increasing power requirements related to the shaft sinking activities.

A power supply and services contract for the temporary generators has been signed with Aggreko International Projects Ltd. Mobilisation has been initiated with the generator pad established. Commissioning of Phase 1 is scheduled during the September quarter to support the start of pre-sink activities.

The Karowe UGP is targeting the substantial resources remaining below the economic extents of the open pit in the South Lobe.

The LHS method is planned to systematically drill and blast the entire lobe on a vertical retreat basis. In LHS, a significant proportion of the blasted muck is left in the stope during blasting and stoping to stabilise the host rock with only the swell extracted during the drill and blast phase. Mucking will take place from draw points from the 310L extraction level. Once the column is fully blasted, the stope will be drawn empty by mucking the draw points.

The bottom-up approach of the LHS mining method takes advantage of the higher value EM/PK(S) kimberlite unit at depth in the South Lobe at Karowe, and balances high initial capital costs with low operating costs while de-risking the project with respect to the geotechnical and hydrogeological aspects of the host rocks, according to Lucara.

A revised project cost and schedule has been developed that captures the detailed engineering and design work through 2020 until May 2021, incorporating all changes, improvements, and COVID-19 related delays. Overall capital expenditures, including contingency, have increased marginally by some 4%, to $534 million, driven by the increase to the production shaft diameter and additional mine development.

The schedule to 75% of full production has increased by 1.3 years, driven mainly by COVID-19-related delays to commence the shaft pre-sinking and additional planned time for shaft station break-outs and ground support, Lucara added.

During 2020, Lucara negotiated and signed a self-build agreement with the Botswana Power Corp (BPC) for the construction of two substations and a 29-km-long 132 kV transmission line from BPC’s newly established Letlhakane substation to the Karowe mine. The planned route follows an existing regional 400 kV line and then runs parallel to the existing 11 kV transmission line currently supplying bulk power to the Karowe mine.

The new power infrastructure will provide the required power for the current open pit, processing plant and the underground mine expansion. Commissioning of and handover to BPC is scheduled for the December quarter of 2022. Construction of substations is scheduled to commence this quarter and power line construction in the March quarter of 2022, the company said.

JDS Energy & Mining Inc is the engineering procurement and construction manager for the execution of the Karowe UGP and is currently building up the on-site project team in conjunction with Lucara’s owners team and working in close cooperation with the Karowe Diamond Mine operations team.

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.”

TOMRA takes XRT ore sorting testing virtual in face of COVID-19 restrictions

TOMRA Sorting Mining is bringing ore sorting testing capabilities to its stay-at-home mining customers though the development of virtual testing facilities that enable them to take informed purchasing decisions for their processing plants, regardless of location.

This is the latest action in the company’s plan to provide its customers the support they need to take their business forward in the face of current COVID-19-related restrictions.

“Ensuring business continuity at this time is of paramount importance for mining operations,” TOMRA Mining said. “This includes taking forward ongoing investment projects in sorting equipment to improve their efficiency and the quality of their product.”

TOMRA Mining is leveraging digital technology to help customers identify the best sorting solution for their mine by offering them remote access to its Test Center in Wedel, Germany, a facility that has capabilities for all applications, according to the company.

“TOMRA’s temporary Virtual Demonstration and Test Solution will enable mining companies to test the sorting solutions on their samples without leaving their office,” the company said. “They will just need to book a session with their TOMRA sales representative and ship a sample of their minerals to the Test Center, which will conduct the test.”

Once testing is complete, mining customers will receive a video of their material being sorted and be able to discuss the results with a TOMRA sales person and the Test Center’s experts via video call, the company said. “With their support, they will be able to make a decision on the following steps and take the project forward without delay,” it added.

Albert du Preez (pictured), Senior Vice President and Head of TOMRA Sorting Mining, said: “At TOMRA, we work closely with our customers to devise the solution that is perfect for their operation. The visit to one of our test centres can be an important step in this process, as it enables them to work out with our teams the best combination of technologies and develop the flowsheet for their ore sorting plant.

“With this virtual solution, we are able to provide this support, taking our Test Center to our customers’ office so they can make an informed decision on an important investment. This means that they are able to take their business forward in the current situation.”

TOMRA’s test centres play a key role in the company’s collaborative approach to supporting customers with their ore sorting requirements, according to the company. Based on the tests conducted on TOMRA equipment with material from the customer’s mine, the centre can provide an initial feasibility study and detailed reports on the machine’s performance with the sample. With this information and the advice of the centre’s experts, the customer can proceed with their investment with confidence, the company says.

The opportunity for the customer to see first-hand the equipment at work on their sample and discuss the options with TOMRA’s team provides important added value, according to the company.

This was the experience of John Armstrong, VP Mineral Resources at Lucara Diamonds, who visited the Test Center in Wedel when researching a solution for the diamond mine in Karowe, Botswana.

“We gained a lot of confidence in the people at TOMRA, in the technology that they were presenting to us, and the possible solution that it provided to the Karowe mine…We could also see that they had already gone down the road of the next step in X-ray Transmission (XRT) technology, so they were not just focused on one particular module to present to us, but they were working on different modules.

“That helped alleviate some of our concerns about the robustness of the platform and the technology itself, which ultimately led us to use TOMRA as the solution.”

Lucara has since gone on to recover some of the largest diamonds in history with the TOMRA XRT system that was installed following this visit to the Test Center.

In addition to developing this Virtual and Demonstration and Test Solution in reaction to the COVID-19 outbreak, TOMRA has increased stocks of critical components to ensure its ability to fulfil current and future orders, and to ensure the supply of spare parts without disruption.

And the company is leveraging digital technology not only to take the expertise of its test centres to customers, but also by using its remote service and training tools to support their equipment while respecting social distancing safety measures, it said.

Lucara and TOMRA continue to recover rare diamonds at Karowe

Lucara Diamond Corp, which owns the Karowe diamond mine, has TOMRA and its XRT ore sorting technology to thank for a lot of its recent success recovering high value diamonds at the Botswana operation.

In production since 2012, the mine is recognised as one of the foremost producers of very large, high-quality Type IIA diamonds in excess of 10.8 ct.

Historic recoveries include the 1,109 ct Lesedi La Rona – the second-largest gem quality diamond ever found – and the 813 ct Constellation diamond. This success at Karowe has recently continued, with rare gem quality blue and pink diamonds recovered in September.

Initial work on the mine was carried out by previous owners in the 1970s with the technology available at the time, which had its limitations.

Eira Thomas, CEO of Lucara, said: “What we realised in looking at the diamonds that resulted from that work is that many of them were actually broken.

“When production started, it became apparent that the diamond population was quite coarse, and that necessitated a re-think on how we could adjust or optimise flow sheet focused on diamond value preservation. That was our real focus and goal in starting the conversation with TOMRA, about how can we do this better, how can we actually get diamonds out of our mineralised ore in a more efficient way and in a way that actually maximises the value of those diamonds and minimises the damage of those goods.”

The AK6 Kimberlite, found in Karowe, presents a difficult challenge, as John Armstrong, Vice President, Technical Services for Lucara, explained: “It has a very high DMS yield, in that up to 10% to 15% of the material that would go into the plant would report as a heavy-metal concentrate, making it a very difficult orebody to process in a traditional diamond processing scenario.

“We undertook a series of testing campaigns and investigations to explore alternative technologies. We elected to go with TOMRA as our partner in moving forward in getting this technology to the mine into part of the circuit that hadn’t been envisioned previously.”

TOMRA’s solution delivered very quickly, exceeding all expectations: “When we put in the large diamond recovery circuit in 2015, it was within two weeks of making this investment, which was somewhere around $30-35 million, that we recovered those two exceptionally large diamonds, so in this case it was under two weeks we’d already had two times our return on that investment,” Thomas said.

Thomas said while Lucara felt TOMRA’s technology was the best on offer, its collaborative approach and willingness to work with Lucara stood out.

“We weren’t entirely certain what the solution was going to be, we just felt that by working with a team of experts that understood the problem and had technology that could help us, we could together come up with a solution that made sense. And, I think, that was the big opportunity for us as we sought in working with TOMRA.”

Thomas added: “I think the Lesedi and The Constellation recoveries really did open up a lot of eyes, and I think it opened a lot of minds to the idea that technology can and will make a big difference to not only existing diamond mining operations, but future mining opportunities, and it’s a great testament to the efforts that we’ve made in collaboration with TOMRA to really get out and tell the story.”

Lucara looks to go underground at Karowe following feasibility study

Lucara Diamond Corp looks like having a combined open pit and underground future at its Karowe diamond mine, in Botswana, after a feasibility study showed the company could double the mine life of the operation for $514 million in pre-production capital.

Already one of the world’s most prolific producers of large, high value type IIA diamonds and the only diamond mine in recorded history to have produced two +1,000 ct diamonds, Karowe’s existing open pit and underground expansion showed off life of mine production of 7.8 Mct to 2040, a payback period of 2.8 years and an after-tax NPV (5% discount) of $718 million.

Eira Thomas, President and CEO, said: “Lucara is highly encouraged by the results of the Karowe Underground feasibility study which has outlined a much larger economic opportunity than first envisaged in the 2017 PEA and represents an exciting, world class growth project for our Company.

“Diamond deposits are rare and getting rarer. In this context, we are extending a mine that is in a class of its own, having produced 15 diamonds in excess of 300 carats, including 2 greater than 1,000 carats in just seven years of production.  Further, we have sold 10 diamonds for in excess of $10 million each, including the record-setting 813 ct Constellation which sold for $63.1 million.”

A significant portion of the cost to expand the mine underground can be funded from cash flow, according to Thomas, and the investment is expected to be paid back in under three years, as the underground expansion allows Lucara to exploit the highest value part of the orebody first and generate more than $5.25 billion in gross revenue, she added.

The Karowe mine has produced 2.5 Mct since 2012 and generated $1.5 billion in revenue. The FS looks to double the mine life from the original mine design of 2010 and add net cash flow of $1.22 billion and gross revenue of $5.25 billion.

The long hole shrinkage (LHS) underground bulk mining method has been selected for the underground deposit, which should provide early access to higher value ore, allows for a short pay back period of 2.8 years and low operating costs of $28.43 per tonne processed, according to the company.

On the basis of a construction start in mid-2020, ore from underground mining is expected to seamlessly integrate into current operations providing mill feed starting in 2023 with a ramp up to 2.7 Mt/y to the processing plant by 2026, and the opportunity to increase throughput.

Current production rates will be maintained through the underground ramp up period.

The Underground is designed to access the South lobe kimberlite resource below the current planned bottom of the open pit (which is expected to be at approximately 700 m above sea level (masl), to a depth of 310 masl.  Access to the South Lobe underground will be via two vertical shafts (production and ventilation) of approximately 765 m and 715 m deep, respectively.

The study identified key focus areas of hydrogeology, geotechnical constraints of the kimberlite and host rocks, which have been addressed through an intensive set of work programs and data collection that commenced during the PEA completed in November 2017 and were substantially updated and augmented by the FS study, the company said.

TOMRA XRT technology recovers massive diamond at Lucara’s Karowe mine

Lucara Diamond Corp claims to have found and recovered one of the largest diamonds in recorded history at its Karowe operation in Botswana.

The 1,758 ct diamond was recovered through Lucara’s X-ray Transmission (XRT) circuit, commissioned in April 2015 by TOMRA Sorting Mining.

Lucara said it is the largest diamond recovered in Botswana, and the largest diamond to be mined at Karowe to date. It comes on top of the 1,111 ct diamond the company recovered in 2015.

“Weighing close to 352 g and measuring 83 mm x 62 mm x 46 mm, the diamond has been characterised as near gem of variable quality, including domains of high-quality white gem,” Lucara said.

Since commissioning of the XRT circuit in 2015, a total of 12 diamonds in excess of 300 ct have been recovered at Karowe, including two greater than 1,000 ct, from a total production of around 1.4 Mct. Of the 12 plus-300 ct diamonds recovered, 50% were categorised as gem quality with 11 sold to date generating revenue in excess of $158 million, Lucara said.

Geoffrey Madderson, Diamond Segment Manager for TOMRA Sorting Mining, said: “As the largest diamond ever recovered by a mechanical process, it reinforces the unparalleled value XRT offers kimberlite and diamond mining companies. Lucara’s innovative strategy, in combination with TOMRA’s world-class sensor technology, has once again proved an enormous success.”

Eira Thomas, Lucara’s CEO, said: “Lucara’s technologically-advanced, XRT diamond recovery circuit has once again delivered historic results. Karowe has now produced two diamonds greater than 1,000 ct in just four years, affirming the coarse nature of the resource and the likelihood of recovering additional, large, high quality diamonds in the future, particularly as we mine deeper in the orebody and gain access to the geologically favourable EM/PK(S) unit, the source of both of our record breaking, plus-1,000 ct diamonds.”

TOMRA’s COM XRT 2.0 mineral ore sorter tackles even higher throughputs

X-ray ore sorting is already making great waves across the mineral processing industry by reducing plant throughputs, increasing head grades and cutting operating costs. One of the leaders in this growing field, TOMRA, believes its new COM XRT 2.0 sorter takes these attributes to another level.

This upgraded model features higher belt speed and throughput, translating directly into increased productivity in mineral processing. It also offers increased wear resistance and longer component lifetime, with quick and safe maintenance through providing easier access to replaceable components.

Ines Hartwig, Product Manager at TOMRA Sorting Mining, said the valuable experience gained over the past 15 years, through monitoring and maintaining the TOMRA COM XRT units operating in the field, has been incorporated into the design of the TOMRA COM XRT 2.0.

“Our sorters have been operating under harsh conditions in both hot and cold climates, sorting wet and dry feed across a wide range of commodities,” Hartwig said.

The speed of the belt in the new design has been increased from 2.7 m/s to 3.5 m/s, while the more powerful X-ray system accommodates the sorting of larger-sized material due to better X ray penetration.

“Higher levels of belt occupancy are facilitated by our improved data processing capacity, and this allows the particle size of the feed to be increased,” she said. “The maximum size of the particles that the TOMRA COM XRT 2.0 can handle is between 100 mm and 125 mm, depending on the material, which also contributes significantly to throughput capacity.”

She notes these higher levels of capacity are particularly valuable for larger mines, as they reduce the number of machines required, and therefore also decrease capital and operating expenditure.

The unit boasts a highly selective ejection system, using data processing in combination with precise control of the pneumatic valves which eject the selected material from the stream. Driving this system is TOMRA’s proprietary data processing pipeline that links sensors, image processing and the valve control boards.

The performance of this ore sorting technology has been proven at Ma’aden Phosphates’ new $560 million processing plant at the Umm Wu’Al project in Saudi Arabia, one of the largest integrated phosphate fertiliser facilities in the world, according to TOMRA. TOMRA Sorting Solutions has installed nine of its TOMRA COM XRT sorting units, each with an operational width of 2.4 m, to process a 1,850 t/h sorter feed at this facility (pictured, top).

The objective of the sorters is to reduce the milling and flotation of silica in the plant process, using a dry technology at a low cost per tonne. The TOMRA units achieve this by removing more than 90% of the chert in the +9 mm fraction, which makes up half of the plant feed, before the phosphate is fed to the milling and flotation circuit. This leads to the removal of over 1.2 Mt/y of SiO2, which does not have to be crushed, ground and floated.

This installation considerably improved the mill performance by reducing the consumption of energy, water and chemicals per tonne of final product, TOMRA said. All of this was achieved with a smaller sorting plant footprint. The saving in flotation reagents, alone, amounts to almost $8 million/y, according to the company.

In Botswana, TOMRA Sorting Solutions has installed two TOMRA COM XRT 2.0/1200 sorters in the mega-diamond recovery (MDR) circuit of Lucara Diamonds’ Karowe mine. Located directly after the primary crusher and ahead of the process plant, the MDR circuit treats material in the size range between 50 mm and 120 mm. It maximises the upfront recovery of exceptional diamonds before the ore reaches the comminution processes, where diamond damage may occur.

“The machine has proven itself through its high availability throughout its first year of operation there,” Hartwig said.

TOMRA Sorting Solutions also has several smaller units in portable and containerised configurations in many different countries, where they must operate in a variety of climatic conditions from arctic to tropical. These machines sort minerals ranging from copper, iron ore and coal to industrial minerals, chrome and diamonds.

Trollope to take over mining at Lucara’s Karowe diamond operation

Aveng Moolmans and Lucara Diamond Corp have agreed to cut short a six-year mining contract at the Karowe mine, in Botswana, following equipment availability issues and difficulties with waste mining, the diamond miner said.

Moolman Mining Botswana, an Aveng subisidiary, was awarded the contract to deliver the full suite of mining services at the Karowe mine, including all drill, blast, load and haul functions for both ore and waste, in January 2017.

In Lucara’s June quarter results, it said the two companies had continued to work to “find a solution” to the problems experienced during the March quarter of 2018 and, following extensive discussions in May and June, both parties had agreed to terminate the contract at the end of 2018.

In the March quarter, ore mined volumes and carats recovered were as expected, but waste mining was lower than forecast at just under 4 Mt.

Lucara said performance stepped up “considerably” during the June quarter – with 4.4 Mt of waste mined – and continued through the month of July, the first full month of transition between Moolmans and new contractor Trollope Mining Services.

As a result of this, waste mining was still expected to be within guidance (13-16 Mt) for the year, while diamonds recovered were expected to total 270,000-290,000 ct.

Lucara said of the contractor transition: “The addendum provides for a transition period of up to six months to allow for a new mining contractor, Trollope, to gradually assume responsibility for both ore and waste mining from Moolmans, with full responsibility for all mining activities to be the responsibility of Trollope as of January 1, 2019.”

Trollope, based in Johannesburg, South Africa, has previously worked with companies such as Exxaro, Anglo American, Harmony Gold and BHP.

Aveng Moolmans took over from former contractor Eqstra Botswana in 2017, which also had its contract cut short.