March 27, 2022 18:00 ET | Source: Perseus Mining Limited Perseus Mining Limited
PERTH, Western Australia, March 27, 2022 (GLOBE NEWSWIRE) -- Perseus Mining Limited (ASX/TSX: PRU) has updated its Life of Mine Plan (“LOMP”) for its Sissingué Gold Mine (“SGM”) and satellite deposits, Fimbiasso and Bagoé, in Côte d’Ivoire (collectively “Sissingué”).
Perseus’s Managing Director and CEO Jeff Quartermaine said:
“The Sissingué Gold Mine has been an important part of Perseus’s geopolitically diversified asset portfolio since commencing commercial production in 2018 with an estimated 4.5-year mine life. Since then, the mine has consistently produced gold in excess of forecasts and importantly, generated significant amounts of free cashflow. This updated LOMP incorporates the processing of ore from satellite deposits at Fimbiasso and Bagoé as well as the Sissingué Gold Mine, and results in the life of the Sissingué operation being extended out till at least March 2026 which enables Perseus to continue generating material benefits for all of our stakeholders, including the residents of our host communities at Fimbiasso and Bagoé.”
Sissingué is located in northern Cote d’Ivoire in the West African Craton where gold is mined in Paleoproterozoic (Birimian) rocks of the southern extension of the Syama Greenstone Belt and the western margin of the Senoufo Greenstone Belt. Gold deposits at Sissingué are orogenic, greenstone hosted.
The SGM main pit mineralisation is structurally controlled and mainly hosted within a granitic stock associated with a network of quartz-carbonate veins and veinlets with associated pyrite and arsenopyrite dissemination. Gold-bearing veins have a dominant NNW to NS trend and are steeply dipping. Disseminated mineralisation is also located in the alternation envelops of the mineralised quartz veins.
SGM commenced commercial gold production at the end of March 2018 and by 30 June 2022 approximately 367,500 ounces of gold are forecast to have been produced at the mine. The sources of ore to be processed at Sissingué during the remaining 3.7 years of mine life, as currently defined, are SGM, Fimbiasso and Bagoé deposits. Each deposit consists of multiple pits and the ore feed will be supplemented with stockpiles at SGM as detailed in Table 3. To ensure the mill is run at full capacity in the last seven months of mine life, reducing processing and general administration (G&A) unit rate costs, stockpiled mineralised waste will be used to supplement ore feed. Ore from Fimbiasso and Bagoé will be stockpiled temporarily on site then transported to Sissingué for process plant feed as per milling schedule. Waste material will be taken to the waste dump located near the pits. Tailings from the process plant will be stored in a single, plastic high-density polyethylene (HDPE) lined, tailings storage facility located near the Sissingué process plant.
Many of Sissingué’s operational workforce live in the communities located near the existing mine and processing facility, and the satellite deposits. An on-site camp has been constructed at SGM to accommodate members of the workforce who are not local residents.
Figure 1 is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/5849bbd8-5a71-4ea5-b894-1b15d5df0dda
Figure 2 is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/a82240f2-5b70-4f8f-8d4a-a921536cfd51
Figure 3 is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/2a80cbe4-6337-46ba-a22f-40b927965153
Figure 4 is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/bc888168-89f7-4939-b629-b8008ff7f6c3
MINERAL RESOURCES AND ORE RESERVES SUMMARY
For a comprehensive description of SGM Mineral Resources and Ore Reserves estimates, refer to the JORC tables included in Appendix 1, and to the news release titled “Perseus Mining Updates Mineral Resources and Ore Reserves” dated 26 August 2020 for all reference to the Fimbiasso Deposits and to the news release titled “Perseus Mining Updates Mineral Resources and Ore Reserves” dated 24 August 2021 for the Bagoé Deposits. Table 1, 2 and 3 below summarise the currently estimated Mineral Resources and Ore Reserves at Sissingué.
Table 1: Sissingué Measured and Indicated Mineral Resources – 31 December 2021 1,2
Table 2: Sissingué Inferred Mineral Resources – 31 December 2021 2
1. Measured and Indicated Mineral Resources are inclusive of Ore Reserves. 2. Rounding of numbers to appropriate precisions may have resulted in apparent inconsistencies. 3. Based on February 2022 Mineral Resource model constrained to US$1,800/oz pit shell. 4. Depleted to 31 December 2021 mining surface. 5. 0.6g/t gold cut-off applied to in situ material. 6. Based on March 2020 Mineral Resource models constrained to US$1,800/oz pit shells. 7. 0.8g/t gold cut-off applied. 8. Based on May 2021 Mineral Resource models constrained to US$1,800/oz pit shells. 9. 0.8g/t gold cut-off applied to oxide, 1g/t applied to transition, 1.2g/t applied to fresh (Veronique deposit only).
Table 3: Proved and Probable Ore Reserves as at 31 December 2021 5, 7
Notes: 1 Depleted to 31 December 2021 mining surface. 2 Based on February 2022 Mineral Resource model constrained to US$1,800/oz pit shell and depleted to 31 December 2021 mining surface. 3 Based on February 2022 Ore Reserve estimation. 4 Variable gold grade cut-off for each material type, ranging from 0.40 g/t to 1.00 g/t at Sissingué deposits, from 0.80 g/t to 1.50 g/t at Fimbiasso deposits and from 1.00 g/t to 3.00 g/t at Bagoé deposits. 5 Inferred Mineral Resource is considered as waste. 6 Based on EOM December 2021 stockpile balance report. 7 Rounding of numbers may result in apparent mathematical inconsistencies.
Based on detailed mining and processing schedules recently prepared as part of the life of mine planning process, the key forecast operating parameters for Sissingué are summarised in Table 4. To illustrate the changes to the FY23 LOMP from the previous FY22 LOMP published in August 2021, equivalent data is tabulated below. It should be noted that the FY23 LOMP commences 1 July 2022 and accounts for actual depletion of Ore Reserves between July 2021 to December 2021 and forecast depletion between 1 January 2022 and 30 June 2022.
Mining cost estimates in the updated LOMP are based on projected costs using the current contract with mining contractors, SFTP, who have been conducting mining activities on site since mining operations started. SFTP is expected to perform the full mining, drilling and grade control service required at Sissingué. Explosive costs are based on the projection of current contract prices provided by contractor, Maxam, a leading explosives manufacturer and distributor.
Gold recovery rates and processing costs are based on actual results achieved in the last 12 months and combined with forward projections based on a comprehensive metallurgical test work program for areas with no experiential data. Processing costs include costs associated with all consumables including maintenance, electricity, fuel, labour, and other processing overheads.
G&A and other costs are based on actuals and budget projections. G&A operating costs include all labour costs, Abidjan regional office costs, HR administration costs as well as all costs associated with the management of the environment, OH&S, security, government and community relations, general administration including insurances and other contracts.
Sustaining capital costs include stage lifting of the tailings storage facility (TSF), closure costs, progressive clearing, contractor demobilisation, and plant modifications. The total estimate of sustaining capital is US$7.6M million which over the current life of mine equates to US$30/oz of gold produced. Sustaining capital does not include any capital costs estimated for the delineation of additional Mineral Reserves and Ore Reserves or the establishment of new open pit or underground mining operations. Any such developments will be regarded as development capital and disclosed accordingly.
1 Includes all ore and waste mined ex-pit but excludes rehandle movement.
2 Excludes pre-strip costs that have been capitalised.
3 Assumes a gold price of US$1,500/oz for Ore Reserve and Royalty calculations, and US$1,250/oz for the DFS.
Based on the estimated Ore Reserves summarised in Table 2: Sissingué Inferred Mineral Resources – 31 December 20212
10. Measured and Indicated Mineral Resources are inclusive of Ore Reserves. 11. Rounding of numbers to appropriate precisions may have resulted in apparent inconsistencies. 12. Based on February 2022 Mineral Resource model constrained to US$1,800/oz pit shell. 13. Depleted to 31 December 2021 mining surface. 14. 0.6g/t gold cut-off applied to in situ material. 15. Based on March 2020 Mineral Resource models constrained to US$1,800/oz pit shells. 16. 0.8g/t gold cut-off applied. 17. Based on May 2021 Mineral Resource models constrained to US$1,800/oz pit shells. 18. 0.8g/t gold cut-off applied to oxide, 1g/t applied to transition, 1.2g/t applied to fresh (Veronique deposit only).
, the mining production profile for Sissingué is forecast to be as shown in Error! Reference source not found. below. No Inferred Mineral Resources have been included as mill feed in the updated LOMP.
Ore and waste will be mined from all Sissingué pits. Ore from the Fimbiasso and Bagoé deposits will be stockpiled temporarily on their respective sites then transported to SGM for processing as per the mill feed schedule. Mill feed will be complimented with the remaining ore stockpiles at Sissingué, with additional feed supplement coming from mineralised waste material to ensure the mill runs full capacity in the final seven months of mine life, minimising the processing and G&A unit rate costs.
Mining is currently expected to be complete within four years of operation from 1 July 2022. Mining will start at SGM and Fimbiasso deposits in the first 18 months, the majority of ore feed will come from Fimbiasso. At this time mining at SGM will be mostly from satellite pits and waste stripping of the main pit, during which time mining will be accelerated at the Fimbiasso deposit. Current ore stockpiles will supplement mill feed as required. After mining at Fimbiasso is complete, Bagoé mining is scheduled to start following equipment relocation. Mining of the SGM deposit will continue while the Bagoé deposit is being mined. In this period, mining at SGM Main pit will be sufficiently advanced to mine high-grade ore and complement lower feed grade ore from Bagoé. This will result in higher gold production in FY25 compared to previous years.
Figure 5 is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/ff525f27-2fde-4fab-bde8-9293447fb844
Gold production in FY23 will mainly be derived from ore sourced from Fimbiasso deposit, oxide ore from SGM satellite deposits and existing stockpiles at SGM. Meanwhile, the pre-strip in the SGM main pit will be undertaken to access the ore zone. Pre-stripping at SGM main pit is expected to take 18 months before access into the main ore zone is achieved.
In FY24, mining in Fimbiasso will be completed in the first half of the year and will be replaced by Bagoé deposit as the main ore source. By second half of FY24, the main ore zone in the SGM main pit will be exposed. Stockpiled material will sustain mill feed at full capacity.
The highest production year in the LOMP is FY25. In this period, high grade ore will be mined from both the SGM main pit and the Bagoé deposit. Ore from Bagoé will provide the main source of high-grade mill feed ore. Mining at the SGM main pit will be completed by the third quarter of FY25, requiring ore from Bagoé deposit to be supplemented with remaining stockpiles available at SGM during the fourth quarter.
Based on the LOM schedule, mining and processing at SGM will be completed in FY26. Mining will be finished in February 2026 and processing will be completed the following month, March 2026. In this period the mill feed will be supplied from Bagoé deposit supplemented with stockpiled mineralised waste. The use of mineralised waste will enable the mill to operate at full capacity, resulting in lower unit processing costs and G&A. By the end of March 2026, approximately 650,000 tonnes of mineralised waste stockpiles will remain. This material may be processed at a later date subject to it being economically viable.
The processing rate is forecast to average 1.4 million tonnes per year over the 3.7 years of mine life. The processing rate in this LOM has been increased from the previous LOM from 220tpoh to 260tpoh and is based on experiential knowledge and current milling rates experienced at SGM.
The forecast average gold production for the remaining mine from 1 July 2022, is estimated at approximately 72,000 ounces at an average head grade of 1.7g/t and an average metallurgical recovery of 91.4%. A total of 252,000 ounces of gold are forecast to be recovered over the life of operation.
Figure 6 is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/b42f50db-eefc-426c-bc2c-b0a706db730e
This announcement was approved for release by Perseus Mining Limited’s Managing Director and CEO, Jeff Quartermaine.
All production targets referred to in this report are underpinned by estimated Ore Reserves which have been prepared by competent persons in accordance with the requirements of the JORC Code.
The information in this report that relates to Mineral Resources for Sissingué is based on information compiled by Ms Christine Shore, a Competent Person who is a Fellow of The Australian Institute of Mining and Metallurgy. Ms Shore is a full-time employee of Perseus Mining, and she has no economic, financial or pecuniary interest in the company. Ms Shore has sufficient experience that is relevant to the style of mineralisation and type of deposit under consideration and to the activities which she is undertaking to qualify as a Competent Person as defined in the 2012 Edition of the “Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves” and a Qualified Person as defined in NI43-101. Ms Shore consents to the inclusion in this report of the matters based on his information in the form and context in which it appears.
The information in this report that relates to Mineral Reserves for the Sissingué deposit is based on information compiled by Mr Craig Fawcett, FAusIMM CP, who is a full-time employee of Perseus Mining. Mr Fawcett has sufficient experience which is relevant to the style of mineralisation and type of deposit under consideration and to the activities which he is undertaking to qualify as a Competent Person as defined in the 2012 Edition of the “Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves” and a Qualified Person as defined in NI43-101. Mr Fawcett consents to the inclusion in this report of the matters based on his information in the form and context in which it appears.
The information in this report that relates to Mineral Resource and Ore Reserve estimates for the Fimbiasso deposits was first reported by the Company in a market announcement “Perseus Mining Updates Mineral Resources and Ore Reserves” released on 26 August 2020. The information in this report that relates to Mineral Resource and Ore Reserve estimates for the Bagoé deposits was first reported by the Company in a market announcement “Perseus Mining Updates Mineral Resources and Ore Reserves” released on 24 August 2021. The Company confirms that all material assumptions underpinning those estimates and the production targets, or the forecast financial information derived therefrom, in that market release continue to apply and have not materially changed. The Company further confirms that material assumptions underpinning the estimates of Ore Reserves described in “Technical Report — Sissingué Gold Project, Côte d’Ivoire” dated 18 December 2017 continue to apply.
Caution Regarding Forward Looking Information:
This report contains forward-looking information which is based on the assumptions, estimates, analysis and opinions of management made in light of its experience and its perception of trends, current conditions and expected developments, as well as other factors that management of the Company believes to be relevant and reasonable in the circumstances at the date that such statements are made, but which may prove to be incorrect. Assumptions have been made by the Company regarding, among other things: the price of gold, continuing commercial production at the Sissingué Gold Mine, the Edikan Gold Mine and the Yaouré Gold Mine without any major disruption due to the COVID-19 pandemic or otherwise, the receipt of required governmental approvals, the accuracy of capital and operating cost estimates, the ability of the Company to operate in a safe, efficient and effective manner and the ability of the Company to obtain financing as and when required and on reasonable terms. Readers are cautioned that the foregoing list is not exhaustive of all factors and assumptions which may have been used by the Company. Although management believes that the assumptions made by the Company and the expectations represented by such information are reasonable, there can be no assurance that the forward-looking information will prove to be accurate. Forward-looking information involves 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 anticipated future results, performance or achievements expressed or implied by such forward-looking information. Such factors include, among others, the actual market price of gold, the actual results of current exploration, the actual results of future exploration, changes in project parameters as plans continue to be evaluated, as well as those factors disclosed in the Company's publicly filed documents. The Company believes that the assumptions and expectations reflected in the forward-looking information are reasonable. Assumptions have been made regarding, among other things, the Company’s ability to carry on its exploration and development activities, the timely receipt of required approvals, the price of gold, the ability of the Company to operate in a safe, efficient and effective manner and the ability of the Company to obtain financing as and when required and on reasonable terms. Readers should not place undue reliance on forward-looking information. Perseus does not undertake to update any forward-looking information, except in accordance with applicable securities laws.
Sissingué Gold Mine Mineral Resources & Ore Reserves
Material information summary as required under ASX Listing Rule 5.8 and JORC 2012 reporting guidelines.
The Mineral Resource Statement for the Sissingué Gold Mine (SGM) is reported in accordance with the 2012 Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves (the JORC Code). The classification categories of Measured, Indicated and Inferred under the JORC Code are equivalent to the Canadian Institute of Mining, Metallurgy and Petroleum categories of the same names (CIM, 2014).
This Mineral Resource Estimate (MRE) update includes an additional 24,700 m drilling from 528 Reverse Circulation (RC) holes, drilled in 2021 and is reported excluding mining activity, surveyed up to 31 December 2021 and limited within a constraining pit shell generated at US$1,800 an ounce with updated Sissingué mining and processing costs.
The SGM MRE is comprised of the remaining in situ mineralisation at the SGM mine and material on stockpiles as of 31 December 2021. A total of 46,377 metres of drilling from 13,703 drill holes was available for this MRE. Mineralisation interpretations were informed by Reverse Circulation and Diamond Drilling.
This MRE comprises Inferred Mineral Resources which are unable to have economic considerations applied to them, nor is there certainty that they will be converted to Measured or Indicated Resources through further sampling. The in situ Mineral Resources are potentially exploitable by open pit mining methods.
The information provided in the JORC 2012 Table 1 – Section 3 Estimation and Reporting of Mineral Resources applies to this MRE.
The combined global Mineral Resource for the SGM is estimated as 2.6Mt grading 1.3 g/t gold, containing 108,000 ozs of gold. Additional stockpile inventory, provide a total global Mineral Resources of 7.3Mt @ 1.3g/t for 135,000ozs as shown below in Table 1.
Table 1: SGM Measured and Indicated Mineral Resources – 31 December 2021 1,2,3,4,5
Table 2: SGM Inferred Mineral Resources – 31 December 2021 2,3,4,5
1 Measured and Indicated Mineral Resources are inclusive of Ore Reserves. 2 Rounding of numbers may have resulted in apparent mathematical inconsistencies. 3 Based on February 2022 Mineral Resource model constrained to US$1,800/oz pit shell. 4 Depleted to 31 December 2021 mining surface. 5 0.6g/t gold cut-off applied to in situ material.
The SGM is located in the West African Craton and covers the Paleoproterozoic (Birimian) rocks of the southern extension of the Syama Greenstone Belt and the western margin of the Senoufo Greenstone Belt. Gold deposits at the SGM are orogenic, greenstone hosted in nature.
The SGM main pit mineralisation is structurally controlled and mainly hosted within a granitic stock associated with a network of quartz-carbonate veins and veinlets with pyrite and arsenopyrite dissemination. Gold-bearing veins have a dominant NNW to NS trend and are steeply dipping. Disseminated mineralisation is also located in the alteration envelops of the mineralised quartz veins.
Additional mineralisation is seen within interconnecting mineralised felsic dyke complexes that propagate from the main granite stock. These mineralised felsic dyke complexes, also trending NNW, host the mineralisation for the additional pits in the area, namely Binkadi, Bagoé, Western Arm and Boribana.
Interpretations of domain continuity were undertaken within Leapfrog3DTM software, with mineralisation intercepts correlating to individual lithological domains manually selected prior to creation of a vein and intrusion model (Figure 1). Interpretation was aided by geological pit mapping which ensured that modelling appropriately represented site-based observations and the current understanding of geology and mineralisation controls.
Mineralisation volume domains were delineated using a combination of:
The main granite intrusions where modelled using lithological logging and a lower nominal 0.3 g/t gold cut-off, which provided a low grade (LG) halo mineralised domain. Statistical analysis of the Granite data showed a high grade (HG) sample population. Visually, this was supported by a consistent tenor of mineralisation lying as an internal, higher-grade core within the Granite. This HG internal sub-domain was then modelled, utilising a nominal 1.0 g/t lower cut-off. Cross cutting Felsic dyke complexes where then modelled using structural and lithological logging, assisted by a lower grade cut-off of 0.3 g/t gold.
Figure 1 is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/115283c7-63d6-42dc-8b57-f0832cf4b60c
For all RC holes informing the resource estimate, samples were collected at 1 metre intervals and split at the drill sites using a multi-stage riffle splitter or cone splitter to produce sub-samples weighting 2-3 kilograms.
Diamond core was sawn in half with a diamond blade saw, with the right half sent for assaying and the left half stored in core trays for reference. Core was sampled in 1 metre intervals or to geological contacts.
RC and core samples were securely transported to either:
1) Perseus’s sample preparation facility at SGM where they were dried, crushed to 2mm and a 1kg riffle split portion pulverised to 90% passing 75 microns and assayed with Aqua Regia, or
2) Transported to a local laboratory and assayed using Fire Assay techniques.
Sample condition (dry, damp, wet) and a qualitative description of sample quality (high, moderate, low) were logged for RC holes. Holes were stopped if excessive water was intersected and the samples were considered at risk of smearing, or if sample recovery dropped to <90%.
For RC samples drilled for resource definition, the weight of each entire recovered 1 metre sample was recorded with sample recoveries averaging ~90%. There is no apparent relationship between sample recovery and gold grades in RC drill holes.
Recovered lengths of diamond core were measured for each drill run. Average core recoveries range from 85% in upper saprolite to 100% in fresh rock. There is no apparent relationship between core recovery and gold grades in diamond drill holes.
Sampling precision was monitored by inclusion of 1:20 duplicate field splits for RC samples. Additionally, duplicate pulps were created for 1:20 samples of all types.
Database checks were completed and included:
The drill hole samples are considered appropriate and representative.
The Mineral Resource at Sissingué are delineated from reverse circulation (RC) and diamond core drilling. Typical drill spacing is generally less than 25 metres x 25 metres with most holes drilled at-60 degrees toward either 090 (east) or 270 (west) degrees azimuth, perpendicular to the strike of mineralisation.
Grade Control drilling spacing is 8 metres x 6 metres, drilled either at 55 degrees or vertical, with samples collected every 1.5 metres.
The data type, spacing and distribution are considered sufficient to establish estimates of Mineral Resources.
All gold assaying was completed by external or onsite commercial laboratories with samples dried, crushed to 10mm, and then pulverised to 85% passing 75 µm and assayed using a 25g or 50g charge for fire assay analysis with AAS finish.
Grade control samples were assayed on site using Aqua Regia and through several external laboratories using Fire Assay between 25g and 50g aliquots.
Quality Assurance and Quality Control
Assay accuracy and reliability were monitored by insertion of blanks at 1:20 samples and reference standards (CRMs) at 1:20 samples.
The performances of blanks and standards were monitored as assay results were received.
Intervals of significant gold grades were compared to logging of quartz veining, alteration and mineralisation and chip tray photographs.
Assays were plotted on cross-sections to check that significant intercepts conform to the expected locations of mineralisation and make geometric sense.
Diamond core holes have been drilled at Sissingué to twin RC holes. Portions of 247 RC drill holes were identified to have smeared assays and have been excluded from all resource estimates, statistics, and interpolations. They have been appropriately flagged in the database.
The Quality Assurance and Quality Control (QAQC) data show acceptable precision and no significant bias. Overall assaying quality is considered adequate to support estimates of Mineral Resource.
Estimation methodology – Open pit mineral resources
The 2022 MRE for the SGM was estimated using a combination of Local Uniform Conditioning (LUC) with Ordinary Kriging (OK) using Surpac 2021 and Isatis.
Estimation was constrained within mineralisation envelopes (wireframes) based on geological logging and grade thresholds. The three main host lithologies are Granite, Felsic Dykes and Sediments. Where geological contacts were not clearly controlling the distribution of mineralisation, a grade cut-off of 0.3 g/t gold was used to construct Mineral Resource boundaries. Analysis of the global grade distribution shows that there is a natural change in grade population at around 0.3 g/t gold.
The LUC methodology was used to estimate the gold grades within the major Granite and Sediment units due to the skewed nature of the grade populations. At the completion of the estimations, grade, density and estimation quality items were exported from Isatis and imported into a Surpac format block model for validation and reporting.
The remaining Felsic Dyke domains were estimated using 2m downhole composite gold grade data into 16 mE x 16 mN x 5 mRL sized panels using Ordinary Kriging (OK).
Within the Grade Control (GC) volume, which is limited to the immediate vicinity of the GC drill holes, an OK estimate of gold grade was produced using the GC drill data.
Block model validation was undertaken globally by comparing:
The GC OK estimates are considered to represent a benchmark by which to measure the success or otherwise of the LUC estimates.
The SGM MRE has been classified into Measured, Indicated and Inferred categories, in accordance with the 2012 Australasian Code for Reporting of Mineral Resources and Ore Reserves (JORC Code) and the CIM Definition Standards (CIM, 2014). A range of criteria has been considered in determining this classification, including geological and grade continuity, data quality and drillhole spacing resulting in the MRE being classified as Measured, Indicated and Inferred.
The portions of the MRE classified as Measured have been flagged using an interpreted volume defined by high quality estimation parameters, which includes an average distance to nearest sample of 7 metres and an average distance to all informing samples of 12 metres. The Measured portion of the resource has been drilled on a nominal 6 metres x 8 metres GC spacing.
The portions of the MRE classified as Indicated have been flagged using a sectional interpreted volume defined by medium to high quality of estimation parameters, an average distance to nearest sample of less than 20 metres and an average distance to all informing samples of less than 40 metres. For the Sediment and Granite domains within the main Sissingué pit, due consideration was also given to the geological and mineralisation continuity available due to mining and positive historical reconciliation.
The portions of the MRE classified as Inferred represent the material extending down dip within and peripheral within the mineralised Domains. In these portions, geological continuity is present but not consistently confirmed by 20 metres x 20 metres drilling and incorporates volume extensions past the deepest drilling by up to 40 metres where the domain has not been closed off by drilling. The Inferred portions of the MRE are defined by lower confidence of estimation parameters, an average slope of regression (true to estimated block) of < 0.4 and an average distance to composites used of > 35 metres.
Mineralisation within the model which did not satisfy the criteria for Mineral Resource remained unclassified.
Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. MRE’s do not account for selectivity, mining loss and dilution. This MRE includes Inferred Mineral Resources which are unable to have economic considerations applied to them, nor is there certainty that they will be converted to Measured or Indicated Resources through further sampling.
The Mineral Resource estimate appropriately reflects the Competent Person’s view of the deposit. Optimisations have been run at a USD$1,800 gold price to define the base of mineralisation potentially mineable by open pit mining. The Competent Person endorses the results and classification.
The MRE cut-off grade for reporting of global open pit global gold resources at Sissingué is 0.6 g/t and has been applied to all materials respectively, based on estimates from mining, ore transport and processing costs, expected metallurgical performances of the various material types and a gold price of US$1,800/oz.
Tonnages were estimated on a dry basis.
REASONABLE PROSPECTS FOR EVENTUAL ECONOMIC EXRTRACTION
The SGM MRE, as reported, has been assessed to meet Reasonable Prospects for Eventual Economic Extraction (RPEEE) based on the following considerations.
Mineral resources are reported within optimal pit shells generated using estimates of mining, ore transport and processing costs, the expected metallurgical performances of the various material types and a gold price of US$1,800/oz.
Mineral Resources contained in stockpiles are based on volume estimates calculated from ground survey data, loose bulk densities derived over time by reconciliation of volumes mined (at in situ densities) to stockpile movements and volumes and estimates of stockpile grades based on predicted grades of mined material transferred onto stockpiles and material depleted by processing.
Closing SGM stockpiles as at 31 December 2021 were estimated as shown in Table 3.
Table 3: SGM Closing Stockpiles – 31 December 2021 1
1. Stockpile tonnage and grade estimates are considered sufficiently accurate to support their classification as Measured Mineral Resources.
Material information summary as required under ASX Listing Rule 5.9 and JORC 2012 reporting guidelines.
The updated Ore Reserve estimate for SGM is a depletion of the previous SGM Ore Reserve and update of Ore Reserve estimation based on the latest Mineral Resource estimate for the Sissingué deposit. Further information regarding updates to the Sissingué Ore Reserves are detailed in JORC Table 1 – Section 4 Estimation and Reporting of Ore Reserves.
The SGM Ore Reserve is summarised below in Table 4 and is estimated at 2.6 Mt of ore, grading 1.3 g/t gold and containing 108k ounces of gold. The classification categories of Proved and Probable under the JORC Code (2012) are equivalent to the CIM categories of the same name (CIM, 2014).
Table 4: SGM Proved and Probable Ore Reserves as at 31 December 2021 5,7
1. Based on depletion to 31 December 2021 mining surfaces. 2. Based on Mineral Resource Estimates which were current at February 2022. 3. Based on February 2022 Ore Reserve estimation. 4. Variable gold grade cut-off for each material type, ranging from 0.40 g/t to 1.00 g/t 5. Inferred Mineral Resource is considered as waste. 6. Based on EOM December 2021 stockpile balance report. 7. Rounding of numbers to appropriate precisions may have resulted in apparent inconsistencies.
The changes in the Ore Reserve from last quoted in June 2021 are associated with ore depletion from mining since 30 June 2021 up to 31 December 2021 along with revised Sissingué Ore Reserves driven by an updated resource model. The waterfall graph (Figure 2) below summarises the changes in the SGM Ore Reserves.
Figure 7 is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/d80a4458-8379-4fab-8724-d6b7c43882d6
Table 5: Assumed LOM average operating costs including Fimbiasso and Bagoé deposits
Table 6: Open Pit Cut-Off Grades
Table 7: Metallurgical Recoveries by Material Type and Pit
Ore mined from Sissingué deposits will be temporarily stockpiled based on rock type and grade. Ore from Fimbiasso and Bagoé will be blended with remaining ore from the Sissingué deposit to keep the processing plant at full capacity.
Criteria for ore reserve classification
Ore Reserves have been classified based on the underlying Mineral Resource classifications and the level of detail in the mine planning. The Mineral Resources were classified as Measured, Indicated and Inferred. The Ore Reserves, based only on the Measured and Indicated Resources, have been classified as Proved and Probable Ore Reserves, respectively.
The Ore Reserve is classified as Proved and Probable in accordance with the JORC Code (2012) and CIM (2014), corresponding to the Mineral Resource classifications of Measured and Indicated and considering other factors where relevant. The deposits’ geological models are well constrained. The Ore Reserve classification is considered appropriate given the nature of the deposits, the moderate grade variability, drilling density, structural complexity and mining history.
JORC 2012 Table 1 – Section 1 sampling techniques and data
(Criteria in this section apply to all succeeding sections.)
JORC 2012 Table 1 – Section 2 Reporting of Exploration Results
(Criteria listed in the preceding section also apply to this section.)
JORC 2012 Table 1 – Section 3 Estimation and Reporting of Mineral Resources
(Criteria listed in section 1, and where relevant in section 2, also apply to this section.)
JORC 2012 Table 1 – Section 4 Estimation and Reporting of Ore Reserves