Lucara Announces Updated Feasibility Study for Karowe Underground Project

VANCOUVER, BC, March 13, 2024 /CNW/ - (LUC – TSX, LUC – BSE, LUC – Nasdaq Stockholm)

Lucara Diamond Corp. (“Lucara” or the “Company”) is pleased to announce the filing of a technical report (the “Report”) for the updated Feasibility Study (“FS” or “Study”), prepared in accordance with National Instrument 43-101 – Standards of Disclosure for Mineral Projects (“NI 43-101”) on its Underground Expansion Project
(“UGP” or “Project”) at the Karowe Diamond Mine (“Karowe”) located in Botswana. The Report is titled “Karowe Mine – Botswana 2023 Feasibility Study Technical Report”, with an effective date of June 30, 2023, and was prepared for Lucara by JDS Energy & Mining Inc. The Report is available under the Company’s profile on SEDAR+ at www.sedarplus.ca or from the Company’s website at www.lucaradiamond.com.

Karowe is located in north-central Botswana, one of the world’s most prolific diamond producing areas, and is a producer of large, high value type IIa diamonds and the only diamond mine to have produced four diamonds in excess of 1,000 carats in size. The underground expansion at Karowe is expected to double the mine life, and to generate significant revenue and cashflow out to 2040, extending benefits to the Company, its employees, shareholders, communities surrounding the mine, and Botswana. The Report provides an update to the 2019 underground feasibility study (“2019 FS”) and 2021 financed base case to reflect changes to project duration, capital expenditure, and technical updates to the Project. All amounts are in U.S. dollars unless otherwise noted.

Combined Open Pit/ Underground Highlights

• Extending mine life by 15 years;
• Total life of mine (“LOM”) diamond recoveries of 6.8 million carats;
• Operational highlights include ~42.4 million tonnes of ore mined and ~52.2 million tonnes of ore processed;
• Highest value EM/PK(S) unit of the South Lobe is the dominant rock type mined over the LOM of the underground; a significant source of many large high value diamonds, including the 1,109 carat Lesedi La Rona, the 549 carat Sethunya, and more recently the 1,080 carat Type IIa white stone recovered in August 2023;
• Pre-production capital costs for the UGP totalling $683 million, to be expended over an eight-year pre-production construction and commissioning period until H2/2027, of which three and a half years have already been successfully completed;
• The UGP is projected to generate $1.1 billion in cash flow;
• Fully financed project as announced on January 9, 2024 (link to Press Release), when the Company amended its debt package that was originally entered into in 2021; and
• The amended facilities consist of a project finance facility (“Project Loan”) of $190.0 million (previously $170.0 million) to fund underground development, and a $30.0 million (previously $50.0 million) senior secured working capital facility (the "WCF") which is used to support ongoing operations along with operating cash flow from the Karowe open pit.

William Lamb, President and CEO of Lucara Diamond Corp., commented: "Lucara is excited to share the updated Feasibility Study for the Karowe Underground Expansion Project, which reinforces our strategic decision to extend mine life and continue to generate benefits for our stakeholders. Karowe is a world-class mine, and we look forward to continuing to recover large, exceptional diamonds from the South Lobe at Karowe.”

This report is updated from the original 2019 UGP FS (link to Press Release) and 2021 financed base case (link to Press Release) and encompasses the following significant modifications:

• Project construction progress (surface infrastructure and underground development) to June 30, 2023;
• Revised economic modelling with updated diamond prices and exchange rates, exclusion of sunk costs and inclusion of financing costs;
• Re-baselining the UGP schedule and as a result, the open pit mine and processing facility production plans;
• Re-estimation of the current operations budgets and project capital and operating cost projections;
• Modifications to the mine design;
• Fine tailings storage and management;
• Advancement of detailed engineering designs;
• Re-modeling of the hydrogeological conditions;
• Underground dewatering and grouting methodology; and
• Groundwater management on surface.

Project description

• The UGP is focused on the South Lobe of the AK06 kimberlite;
• The UGP is designed to support operation of a 2.7 million tonnes per annum underground mine and processing plant;
• 8.5 metre finished internal diameter Production Shaft approximately 767 metres deep equipped to hoist a nominal 7,400 tonnes per day of ore and additional development waste;
• 6 metre finished internal diameter unequipped Ventilation Shaft with a planned final depth of 729 metres;
• Extraction of approximately 400 vertical metres of the South Lobe of the AK06 kimberlite from 310 metres above sea level (“masl”) (700 metres below surface) to the bottom of the depleted open pit (approximately 710 masl or 300 metres below surface).

Key Operational Parameters

Table 1: Key Operational Parameters  

Source: 2023 FS

Feasibility Study Approach

The FS has been prepared following Canadian Institute of Mining Guidelines for the development of an underground mine. Production from the underground is planned after open pit operations have been completed and the Company will rely on the processing of stockpiled material during the latter part of the underground development and ramp-up to full production in Q1, 2028.

The results of the FS represent forward-looking information that are subject to a number of risks, uncertainties and other factors that may cause results to differ materially from those presented here.  (See "Cautionary Note Regarding Forward Looking Statements" below.)

operating and Capital Cost Estimates

The mine operating cost estimate for the Karowe Project is based on a combination of experience, reference projects, first principle calculations, budgetary quotes, and factors as appropriate for a FS.

Table 2: Summary of Operating Cost Estimate

Notes:

(1) Average cost per year in which costs occur.

(2) Tonnes processed in relation to operating cost.

Source: 2023 FS

The capital cost estimate was prepared using a combination of first principles, applying project experience and using vendor/ contractor provided budgetary quotes while avoiding the use of general industry factors. The estimate is derived from engineers, contractors, and suppliers who have provided similar services to existing operations and have demonstrated success in executing the plans set forth in the study.

Table 3: Capital Cost Summary

Source: 2023 FS

Economics

The main assumptions with respect to the economic model are listed in Table 4. Table 5 shows the baseline diamond prices by zone.

Table 4: Economic Assumptions

Source: 2023 FS

Table 5: Baseline Diamond Prices

Source: 2023 FS

Sensitivities

A univariate sensitivity analysis was performed to examine which factors most affect the Project economics when acting independently of all other cost and revenue factors. Each variable evaluated was tested using the same percentage range of variation, from -20% to +20%, although some variables may actually experience significantly larger or smaller percentage fluctuations over the LOM. The Project is most sensitive to diamond prices and grade and the least sensitive to capital costs.

Table 6: Sensitivity Results (Post-Tax NPV @ 8%)

Source: 2023 FS

Mineral Resources

The 2023 mineral resource estimate for Karowe incorporates drilling and sampling data obtained prior to 2018, and additional drilling and sampling information obtained in 2018/ 2019 which targeted delineation of the deep extension of South Lobe (deeper than approximately 600m from surface). In 2019, the geological data were used to develop an updated internal geology model for the South Lobe and to update the external contacts for the South, Centre and North Lobes. The 2023 update also includes geological information and production data derived from open pit mining to the end of June 30, 2023.

The 2023 mineral resources for Karowe, as summarized in Table 7, have been classified as either Indicated or Inferred Mineral Resources, according to CIM Definition Standards for Mineral Resources and Mineral Reserves (CIM, 2014). Mineral Resources reported are inclusive of those portions of the Mineral Resource that have been converted to Mineral Reserves and have an effective date of June 30, 2023.

Table 7: Karowe 2023 Mineral Resource Statement (effective date of June 30, 2023)

Notes:

1. Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. All numbers have been rounded to reflect accuracy of the estimate;
2. Mineral Resources are in-situ Mineral Resources and are inclusive of in-situ Mineral Reserves;
3. The base of the South Lobe Indicated Mineral Resource is 250masl and 60masl for the inferred resource;
4. Mineral Resources are exclusive of all mine stockpile material;
5. Mineral Resources are quoted above a +1.25 mm bottom cut-off and have been factored to account for diamond losses within the smaller sieve classes expected within the current configuration of the Karowe process plant;
6. Inferred Mineral Resources are estimated on the basis of limited geological evidence and sampling, sufficient to imply but not verify geological grade and continuity. They have a lower level of confidence than that applied to an Indicated Mineral Resource and cannot be directly converted into a Mineral Reserve;
7. Average diamond value estimates are based on 2023 diamond sales data provided by Lucara Diamond Corp.; and
8. Mineral Resources have been estimated with no allowance for mining dilution and mining recovery.

Source: 2023 FS

Mineral Reserves

The effective date for the Mineral Reserve Estimate contained in the updated FS report is June 30, 2023 and was prepared by Qualified Person (QP) Brandon Chambers, P.Eng. All Mineral Reserves in Table 8 are classified as Probable Mineral Reserves. The Mineral Reserves, except stockpiles, are not in addition to the Mineral Resources, but are a subset thereof.

The QP has not identified any legal, political, or environmental risks that would materially affect potential Mineral Reserves development.

Table 8: Karowe Mineral Reserve Estimate (effective date of June 30, 2023)

Notes:

1. Prepared by Brandon Chambers, P.Eng. JDS Energy & Mining Inc.;
2. CIM definitions were followed for Mineral Reserves;
3. Process recovery of the diamonds was assumed to be 100% as the recoveries were included in the mineral resource block model assumptions and therefore have taken recoveries into account;
4. The bottom elevation of the Probable Reserve is 310 masl;
5. Mineral Reserves are quoted above a +1.25 mm bottom cut-off and have been factored to account for diamond loses within the smaller sieve classes expected within the current configuration of the Karowe Process Plant;
6. Diamond price estimates are provided by Lucara; prices are derived from historical sales and adjusted for current market conditions;
7. Tonnages are rounded to the nearest 100,000 t, diamond grades are rounded to one decimal place to properly reflect the Reserve estimate accuracy;
8. Tonnage and grade measurements are in metric units; contained diamonds are reported as thousands of carats;
9. Open pit Mineral Reserves are estimated at a cut-off value of $37/t based on an open pit mining cost of $13/t, a processing cost of $12/t and a G&A cost of $12/t;
10. Underground Mineral Reserves are estimated at a cut-off value of $35/t based on an underground mining cost of $11/t, a processing cost of $12/t and a G&A cost of $12/t;
11. Mine Call Factor is a modifying factor used by Lucara which tracks the reconciliation between the block model and actual recovered carats. Mine Call Factor is assumed to be 100%, historically this factor has reconciled either near or above 100%, however in the 12-month period prior to the Reserve Statement the Mine Call Factor has deviated away from historical average performance and is currently at 95%;
12. Underground dilution assumptions in the 2019 FS were revised in 2023. Underground dilution included in the Reserve was estimated from the following three sources:

•    1.0 m of zero-grade overbreak from stoping adjacent to the granite host rock;

•    2.7 Mt of zero-grade overbreak from stoping adjacent to sedimentary rocks (based on geomechanical modelling); and

•    Inclusion of inferred KIMB3 kimberlite within the overall pipe shape as zero-grade waste.

13. Stockpile Mineral Reserves are estimated at a cut-off value of $19/t based on a rehandle cost of $2/t, a processing cost of $12/t and a G&A cost of $5/t, when processed at the end of mine life;
14. Stockpile Reserves are not included in the Karowe Mineral Resource Estimate, which covered only in-situ mineralized material;
15. Stockpile Reserves are based on surveyed volumes and block model grades; and
16. Stockpile LOM diamond price is determined from the weighted average of the North, Centre, South - M/PK(s), and South - EM/PK(s) lobe ratios.

Source: 2023 FS

Geotechnical

A geotechnical investigation program was carried out to support underground mine design, building on the open pit and underground preliminary economic assessment (“PEA”) geotechnical modelling carried out in 2017. The geotechnical drilling, sampling and testing program was designed to comply with the data confidence requirements of a FS, in support of a feasibility-level mine design, and leading into optimization of the design implementation. The investigation focused on defining the geotechnical characteristics of the surrounding country rock as well as the South Lobe kimberlite and involved the drilling, geotechnical logging and sampling of 37 diamond drillholes, totaling more than 23,500m, with field and laboratory testing of the core samples. Almost 11,000 tests were conducted on samples across the various lithologies.

Hydrogeology

Water control and hydrogeological context of the deposit and host rocks are key elements in the mine plan. The AK6 deposit sits within layered, sedimentary, regional aquifers that have been documented since the 1980's.

Since the release of the 2019 feasibility study report, five key updates were made:

• The groundwater flow model was updated;
• A planned drainage gallery at the 680 Level (680 L) was not implemented;
• The groundwater flow model in the 2019 FS assumed that grouting in the granites will take place in all underground development and will be 75% successful. The predicted inflow rate in the updated model (2023) only assumed 66% successful grouting during shaft sinking and station development up to January 1, 2026; the model also assumes that no grouting activities are undertaken once underground pumping capacity is available unless particularly high inflows are encountered that hinder development;
• The underground drainage systems were updated; and
• The depressurization target for the open pit slope was updated.

Mineral Processing

The Karowe processing plant has been treating unweathered South Lobe ore since 2015 and mineral processing characteristics are very well understood.

A comminution test program was conducted to test the milling characteristics of the South Lobe material below the open pit to determine if the mill is suitable for deeper EM/PK(S) ore.

The second test involved testing of Tomra’s X-ray Transmission (XRT) machines and associated software to determine their ability to differentiate between diamonds, coal, carbonaceous shale and other waste rock. Due to the high carbon content of coal and carbonaceous shales, they were of greatest concern. The dilution of ore with carbonaceous shales (and the small, sporadic, coal seams contained therein) is anticipated to occur during the later stages of mine life. Testing was conducted by Tomra at their testing facilities in Germany.

Mining

The currently operating open pit at Karowe is a conventional load and haul operation. Open pit mine operations are expected to terminate mid-2025 at an elevation of 713 masl. The mine currently has over three years of surface stockpiled reserves, which will be consumed as required while the Underground mine operations ramp up to commercial production.

The 2019 FS investigated several underground mining methods based on data and information from an exhaustive field program conducted in 2018 and 2019 to define mineral resource, geotechnical, and hydrogeological characteristics necessary for making informed decisions at a FS-level study.

The inability for natural or preconditioned caving to occur has resulted in the development of the Long Hole Shrinkage (“LHS”) mine method, which is essentially a fully assisted cave. The method involves a combination of longhole drilling and blasting to create a large muck pile within the South Lobe, followed by the managed drawdown of the blast material through a panel cave extraction level.

The benefits of the LHS mining method include:

• Highest value ore to be extracted first due to the bottom-up mining approach;
• Minimal development in weak, water-bearing lithologies near surface;
• Dilution will be delayed (occurring after the payback period) as the weaker host rock is not exposed until later in the mine life;
• Development of the underground mine can occur simultaneously with the open pit operations;
• Low operating costs;
• Ease of operation after the drilling and blasting phase is complete and small underground work force requirements;
• Early exclusion of precipitation into the underground workings until the crown pillar is blasted;
• Significant ability to increase production after the drill and blast phase is complete; and
• Designed to manage natural caving should it occur.

Infrastructure

The UGP at Karowe will include the use of existing and new infrastructure at the Karowe Mine. Current and planned infrastructure is designed to support the operation of the mine and processing plant. Project construction over the past two years has led to the completion of most of the surface infrastructure components of the Project.

Permitting

Karowe, which has been operating since 2012, completed its latest Environmental Impact Assessment/ Environmental Management Plan in 2020 (to incorporate the UGP) and received approval from the Botswana Department of Environmental Affairs during the same year.

The mining license was renewed in 2021 for a period of 25 years and expires on January 3, 2046.

Conclusions

It is the conclusion of the Qualified Persons (“QPs”) that the FS summarized in this press release contains adequate data and information to support a FS. Standard industry practices, equipment and design methods were used in the FS. Since the 2019 FS, the UGP has advanced considerably in terms of financing, detailed engineering and construction while the open pit mine and processing facility have operated well and maintained targeted production.

To date, the QPs are not aware of any fatal flaws for the UGP.

Qualified Person (“QPs”)

The FS was prepared under the direction of JDS Energy & Mining Inc. and by leading independent industry consultants. Mr. Gord Doerksen P. Eng is the Project manager and responsible for the study completion and an Independent Qualified Person under National Instrument 43-101. Dr. J.P. Armstrong, Ph.D. P. Geo., the Company's VP Technical Services and a Qualified Person under National Instrument 43-101, and Mr. Doerksen have reviewed and approved the contents of this news release.

The results of the Karowe Underground FS will be summarized in a Technical Report prepared pursuant to Canadian Securities Administrators' National Instrument 43-101 that will be filed on SEDAR+ (https://www.sedarplus.ca) within 45 days of this press release and will also be available on the Company's website (https://lucaradiamond.com/).

On behalf of the Board,

William Lamb

President and Chief Executive Officer

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The information is information that Lucara is obliged to make public pursuant to the EU Market Abuse Regulation and the Swedish Securities Markets Act. This information was submitted for publication, through the agency of the contact person set out above, on March 13, 2024 at 5:00 p.m. Pacific Time.

CAUTIONARY NOTE REGARDING FORWARD LOOKING STATEMENTS

Certain of the statements made herein contain certain “forward-looking information” and “forward-looking statements” as defined in applicable securities laws. Generally, any statements that express or involve discussions with respect to predictions, expectations, beliefs, plans, projections, objectives, assumptions or future events or performance and often (but not always) using forward-looking terminology such as “expects”, “is expected”, “anticipates”, “believes”, “plans”, “projects”, “estimates”, “budgets”, “scheduled”, “forecasts”, “assumes”, “intends”, “strategy”, “goals”, “objectives”, “potential”, “possible” or variations thereof or stating that certain actions, events, conditions or results “may”, “could”, “would”, “should”, “might” or “will” be taken, occur or be achieved, or the negative of any of these terms and similar expressions) are not statements of historical fact and may be forward-looking statements.

Forward-looking information and statements are based on the opinions and estimates of management as of the date such statements are made, and they are subject to several known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of the Company to be materially different from any future results, performance or achievement expressed or implied by such forward-looking statements, including risks related to. The Company believes that expectations reflected in this forward-looking information are reasonable, but no assurance can be given that these expectations will prove to be accurate and such forward-looking information included herein should not be unduly relied upon. 

In particular, this release may contain forward looking information pertaining to the following: potential to and length by which the UGP will extend the life of mine; updated resource and reserves for the Karowe Mine, including the Underground and the total expected life of mine production; estimates of the Company's production, operating margins and sales volumes for the Karowe Mine, including the Underground and associated cash flow and revenues; estimates of the economic benefits of the Underground, including the timing for the UGP to pay back capital; anticipated total capital expenditures for the Underground and the schedule to develop and complete the UGP; continued availability of external financing; that expected cash flows from open pit operations, combined with external financing, will be sufficient to complete construction of the UGP; the ability to integrate the underground operations seamlessly into the existing infrastructure; the timing of key construction milestones including shaft sinking activities; the anticipated mine plan and mining methods; that the decisions taken to de-risk the UGP will be successful; that the people, equipment and materials required to build the UGP will be available when required to maintain the proposed UGP schedule; anticipated changes in diamond pricing, including trends in supplies and demands; changes to foreign currency exchange rate; the Company’s adoption of and compliance with internationally recognized standards including IFC Performance Standards and the Equator Principles; and other forward looking information.

There can be no assurance that such forward looking statements will prove to be accurate, as the Company's results and future events could differ materially from those anticipated in this forward-looking information as a result of those factors discussed in or referred to under the heading "Risks and Uncertainties"' in the Company’s most recently filed Annual MD&A and, in the Company's most recent Annual Information Form available at SEDAR+ at www.sedarplus.ca, as well as the Company’s ability to access the markets and generate revenues at anticipated diamond prices, the Company’s ability to continue to comply with the terms of its debt financing, changes in general business and economic conditions, changes in interest and foreign currency rates, the supply and demand for, deliveries of and the level and volatility of prices of rough diamonds, costs of power and diesel, acts of foreign governments and the outcome of legal proceedings, inaccurate geological and recoverability assumptions (including with respect to the size, grade and recoverability of mineral reserves and resources), and unanticipated operational difficulties (including failure of plant, equipment or processes to operate in accordance with specifications or expectations, cost escalations, unavailability of materials and equipment, government action or delays in the receipt of government approvals, industrial disturbances or other job actions, adverse weather conditions, and unanticipated events relating to health safety and environmental matters).

The foregoing is not exhaustive of the factors that may affect any of our forward-looking statements. Forward-looking statements are statements about the future and are inherently uncertain, and our actual achievements or other future events or conditions may differ materially from those reflected in the forward-looking statements due to a variety of risks, uncertainties, and other factors, including, without limitation, those referred to in this news release. Accordingly, readers and investors should not place undue reliance on forward-looking statements. Forward-looking information and statements are made as of the date of this disclosure and accordingly are subject to change after such date. Except as required by law, the Company disclaims any obligation to revise any forward-looking information and statements to reflect events or circumstances after the date of such information and statements. All forward-looking information and statements contained or incorporated by reference in this news release are qualified by the foregoing cautionary statements.

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For further information, please contact:

Vancouver
Hannah Reynish, Investor Relations & Communications
+1 604 674 0272| info@lucaradiamond.com

Sweden
Robert Eriksson, Investor Relations & Public Relations
+46 701 112615 | reriksson@rive6.ch 

UK Public Relations
Charles Vivian / Jos Simson, Tavistock
+44 778 855 4035 | lucara@tavistock.co.uk

ABOUT LUCARA

Lucara is a leading independent producer of large exceptional quality Type IIa diamonds from its 100% owned Karowe Diamond Mine in Botswana. The Karowe Mine has been in production since 2012 and is the focus of the Company’s operations and development activities. Clara Diamond Solutions Limited Partnership (“Clara”), a wholly-owned subsidiary of Lucara, has developed a secure, digital sales platform which ensures diamond provenance from mine to finger.  Lucara has an experienced board and management team with extensive diamond development and operations expertise.  Lucara and its subsidiaries operate transparently and in accordance with international best practices in the areas of sustainability, health and safety, environment, and community relations.  Lucara has adopted the IFC Performance Standards and the World Bank Group’s Environmental, Health and Safety Guidelines for Mining (2007).  Accordingly, the development of the Karowe Underground Project adheres to the Equator Principles. Lucara is committed to upholding high standards while striving to deliver long-term economic benefits to Botswana and the communities in which the Company operates.