Capstone Completes Minto Mine Phase VI Pre-Feasibility Study
Study extends mine life to 2022 with yearly average copper production of 40 million pounds at an average cash cost of $1.92/lb of payable copper
VANCOUVER, June 18, 2012 /PRNewswire/ - Capstone Mining Corp. ("Capstone") (TSX: CS) today announced the results of the Phase VI Pre-Feasibility Study ("Phase VI PFS") for its Minto copper-gold mine in Yukon.
This study was initiated to apply economic considerations to the Minto South Deposit ("MSD") mineral resource and more specifically extensions to that deposit called Copper Keel and Wildfire in order that it may be converted to a National Instrument 43-101 compliant ("NI 43-101") Mineral Reserve. The study builds on the previous Minto Phase V Pre-Feasibility Study ("Phase V PFS") by incorporating new mineral reserves and a new life-of-mine plan ("LOMP") that includes the additional underground mineral reserves from the Copper Keel and Wildfire zones; optimized pit designs; processing plant capacity improvements; updated costs and economic analysis.
(all amounts in Canadian dollars unless otherwise indicated)
- Mine life extended to 2022 with an average of 40 million pounds of copper production per year;
- Net present value ("NPV"), at a constant US$3.25/pound copper price and a 8.0% discount rate, of $278 million before tax and $192 million after tax;
- Proven and probable open pit and underground mineral reserves have increased to 14.4 million tonnes grading 1.53% copper, 0.58 grams/tonne gold, and 5.12 grams/tonne silver, for a contained 484 million pounds of copper, 270,000 ounces of gold, and 2.4 million ounces of silver;
- Life-of-mine ("LOM") capital cost of $103 million; and
- Life-of-mine cash costs(1) of US$1.92/pound of payable copper, after by-product credits (with gold at US$300/ounce and silver at US$3.90/ounce, as per an agreement with Silver Wheaton).
- Key Performance Indicators associated with the addition of underground mineral reserves at Copper Keel and Wildfire on an after tax basis is an NPV8% of $15 million with an IRR of 31% and capex at $25 million based on an NSR cut-off of C$64.40 per tonne.
(1) The items marked with a "1" are alternative performance measures; please see "Alternative Performance Measures" at the end of this release.
"The Minto Mine has been very successful as the Yukon's first operating hard rock mine since the 1990's, bringing stable long-term employment and royalty benefits to the Yukon. It started operations in 2007 at 1,600 tonnes per day with an eight year mine life, and now, five years later, as a result of successful exploration this latest study and development plan extends the mine life to 2022 at a proposed production rate of 3,750 tonnes per day," said Darren Pylot, President and CEO of Capstone. "In addition, exploration on the Minto property remains on-going to further define and potentially expand the mineral resources, as well as explore additional new zones of mineralization."
Phase VI PFS
The Phase VI PFS was compiled by Capstone with contributions from SRK Consulting (Canada) Inc. ("SRK") for block model validation as well as open-pit and underground geotechnical evaluations; Genivar Inc. ("Genivar") for site infrastructure revisions and ventilation modelling; and Eggert Consulting for information related to metallurgy and mineral processing.
For the purposes of the Phase VI PFS the Area 2, Area 118, Copper Keel, and Wildfire resource sub-domains are now considered continuous, and reported as one deposit, namely Minto South Deposit located immediately south of the Minto Main Pit. The Ridgetop deposit is separate from MSD and is located just over 300 metres south of the MSD sub-domain Area 2/118. The Minto North deposit is located approximately 700 metres north of the Minto Main deposit and the Minto East Deposit is located approximately 200 metres east of the south end of the Minto Main deposit. Two recent discoveries, named Fireweed A and Fireweed B are located approximately 200 metres and 400 metres respectively due east from Minto East. A working model suggests that the Fireweed zones may be structurally offset from Minto East and it remains a priority exploration target. These deposits and other mineral prospects collectively define a general north-northwest trend informally called the Priority Exploration Corridor.
In conjunction with the Phase VI PFS, an internal scoping level evaluation was completed to assess the viability of a larger scale mining and milling operation incorporating more of the lower grade mineral resources in the MSD. This evaluation concluded that there was a poor risk/reward ratio of the large scale operating scenario as compared to the Phase VI PFS and therefore recommended that further studies investigating a major increase in the production rate with a subsequent decrease in unit operating costs should not be pursued at this time.
A primary objective of the Phase VI PFS was to produce a revised mineral resource for the MSD by including new drill results in the MSD area not incorporated in, or obtained subsequent to the Phase V study. The new MSD model uses all of the previous drill data plus newly acquired diamond drill results updated to a cut-off date of July 16, 2011. Exploration drilling since the July 16, 2011 cut-off is not included in the Phase VI PFS and a future mineral resource update is in progress with an anticipated completion in late 2012. There were no modifications to the Minto North and Ridgetop mineral resource estimates.
The following table presents combined mineral resources at a 0.5% Cu cut-off for MSD, Ridgetop, Minto Main, Minto North and Minto East Deposits. The Minto Main Deposit mineral resource has been appropriately reduced to account for all material removed by mining up until December 31, 2011.
Combined Mineral Resource Statement at 0.5% Cu Cut-off for Minto South, Ridgetop, Minto Main, Minto North and Minto East Deposits, January 1, 2012
In the opinion of SRK, Kirkham Geosystems Ltd. and Capstone, the block model resource estimate and resource classification reported herein are a reasonable representation of the mineral resources at MSD, Ridgetop, Minto Main, Minto North and Minto East Deposits at the current level of sampling. The mineral resources presented herein have been estimated in conformity with generally accepted CIM "Estimation of Mineral Resource and Mineral Reserves Best Practices" guidelines and are reported in accordance with Canadian Securities Administrators' NI 43-101. Mineral resources are not mineral reserves and do not have demonstrated economic viability. Only Measured and Indicated mineral resources have been used in the preliminary feasibility study described in this news release and the Phase VI PFS report.
The database used to estimate the MSD was audited by Capstone/SRK and the mineralization boundaries were modelled by SRK based on lithological and structural interpretations. Kirkham Geosystems Ltd. audited the Minto North and Minto East database and modelled mineralization boundaries. The Minto North and Minto East Deposit mineral resource estimates were completed by Garth Kirkham, P.Geo., of Kirkham Geosystems Ltd., an independent qualified person as this term is defined in NI 43-101. These mineral resource estimates were completed as part of the Phase V PFS and have not changed. The mineral resource estimate of MSD was completed by Dr. Wayne Barnett, Ph.D., Pr.Sci.Nat., a NI 43-101 independent qualified person. The effective date of this mineral resource estimate is October 17, 2011. Marek Nowak, P.Eng, analyzed the data, reviewed and validated the mineral resource estimates.
SRK is of the opinion that the current drilling information is sufficiently reliable to interpret with confidence the boundaries of the mineralized domains and that the assaying data is sufficiently reliable to support estimating mineral resources.
The "reasonable prospects for economic extraction" requirement for a mineral resource generally implies that the quantity and grade estimates meet certain economic thresholds, and that the mineral resources are reported at an appropriate cut-off grade taking into account extraction scenarios and processing recoveries. Capstone considers that the Ridgetop and Minto North resource areas are amenable for open pit extraction. The Area 2/118 and Wildfire subdomains of the MSD resource is amendable to combined open pit and underground extraction while the Minto East Deposit and Copper Keel subdomain of the MSD resource will be extracted by underground mining.
Mine Production and Mineral Reserve Estimation
The MSD, Ridgetop, Minto East and Minto North Deposits are planned to be developed by open pit ("OP") and underground ("UG") methods. Open Pit mining in the Phase VI PFS study assumes contractor mining rather than the owner operated scenario proposed in the Phase V PFS. In addition, the initial underground mining (portal and decline development as well as the vertical ventilation raise development) is also by contractor rather than owner operated as indicated in the Phase V PFS. The Phase VI PFS also assumes underground mine production mining and the remaining capital development will be owner operated commencing in the fourth quarter of 2013.
The Phase VI PFS assumes a start date of January 1, 2012. Mining of the Main Pit was completed in April 2011 and can therefore be utilized as an in-pit tailings deposition storage location. Pre-stripping of the Area 2 Open Pit within the MSD commenced in 2011.
Based on a start date of January 1, 2012, the Phase VI open pit and underground mines will produce a total of 13.5 million tonnes ("Mt") of ore and 44.48 Mt of waste over approximately a seven year mine operating life ending in 2019. Approximately 4.36 Mt of ore is planned to be produced from UG mining at a rate of 2,000 tpd. The LOMP accelerates mining and processing of high-grade ore and defers stockpiled lower grade mill feed until the end of the mine life whenever possible. Once active mining is completed, mill operations will continue for an additional three years, processing the accumulated 4.08 Mt of stockpiled ore. Therefore, the total mill operating life is 10 years with final reclamation commencing mid-2022.
Mine design for the Phase VI underground expansion relies on the evaluation of a NSR model that includes estimates of metal prices, exchange rate, mining dilution, mill recovery, concentrate grade smelting and refining payables and costs, freight and marketing costs and royalties. The NSR model was based on a 10 metre x 10 metre x 3 metre block size (see below).
The Phase V pit designs, and subsequently the open pit mineral reserves, have been revised in the Phase VI PFS to reflect LOMP operating costs, metal prices and the exploration results contained with the Minto South Deep ore deposit model. The table below reviews the Whittle™ Parameters utilized to generate pit economic shells. These shells were used to develop optimized pit designs.
Summary of Whittle™ Parameters used for Phase VI Open Pit Design
|Metal Prices and Exchange Rate|
|Copper recovery to concentrate||Max||91%|
|Sulphide Gold recovery to concentrate||Max||70%|
|Sulphide Silver recovery to concentrate||Max||78%|
|Copper grade in concentrate||%||40|
|Gold grade in concentrate||g/t||variable with Cu|
|Silver grade in concentrate||g/t||variable with Cu|
|Concentrate moisture content||8%|
|Payable copper in concentrate||%||96.75|
|Payable gold in concentrate||%||per MRI contract|
|Silver deduction||g/t in conc||per MRI contract|
|Remaining payable silver in concentrate||%||per MRI contract|
|Pit slope angles||Overall||As per Phase V PFS|
|Annual Plant Throughput||Mtpa||1,370,000|
|Waste mining cost||C$/waste tonne||3.12|
|Ore mining cost||C$/ore tonne||3.12|
|Processing cost||C$/milled tonne||16.50|
|G&A cost||C$/milled tonne||11.90|
|Transport, marketing, ins, etc.||US$/dmt conc||169.54|
*Based on terms of royalty stream agreement with Silver Wheaton
The Phase V Underground mineral reserves in the areas of Minto East, Area 2 and 118 were checked with the revised NSR model and remain economically viable. Therefore, these mineral reserves were included in the Phase VI mineral reserves without revision.
The additional Phase VI underground mineral reserves are located in the Copper Keel and Wildfire regions of MSD and were estimated using the following NSR model.
Underground Net Smelter Return Parameters
|Metal Prices and Exchange Rate|
|Cu price||US$/lb Cu||2.50|
|Au price||US$/oz Au||300|
|Ag price||US$/oz Ag||3.90|
|Cu Concentrate Grade|
|Cu in Cu conc||%||96.75|
|Au in all cons||%||per MRI contract|
|Au deduction in all cons||g/t in conc||per MRI contract|
|Ag in all cons||%||per MRI contract|
|Ag deduction in all cons||g/t in conc||per MRI contract|
|Cu conc treatment||US$/dmt conc||per MRI contract|
|Cu refining charge||US$/lb pay Cu||per MRI contract|
|Au refining charge||US$/oz pay Au||per MRI contract|
|Ag refining charge||US$/oz pay Ag||per MRI contract|
|Transport, marketing, ins, etc.||US$/dmt conc||169.54|
|UG mining cost||C$/ore tonne||36.00|
|Processing cost||C$/milled tonne||16.50|
|G&A cost||C$/milled tonne||11.90|
|Total Site Costs||C$/milled tonne||64.40|
Small underground mineralized zones were not converted to a mineral reserve if they required excessive development. The total Minto Mine mineral reserve estimate is summarized below.
Minto - Mineral Reserves by Class for Phase VI
|Diluted Grade||Contained Metal|
|Cu (%)||Au (g/t)||Ag (g/t)||Cu (Mlbs)||Au (koz)||Ag (koz)|
|Open Pit Mineral Reserves|
|Open Pit Subtotal||Proven||5,974||1.58||0.67||5.31||208||128||1,020|
|Underground Mineral Reserves|
|Area 2 / 118||Proven||-||-||-||-||-||-||-|
Life-of-Mine Production and Processing Schedule
The Phase VI mining sequence is divided into various stages. The surface mining sequence commences with ore production from Area 2 - Stages 1 & 2 followed by mining of Area 118, then Minto North, Area 2 - Stage 3 and finally the two stages (North and South pits) associated with the Ridgetop Deposit. Underground mining operations will begin with production from the 118 zone of MSD after the ramp bypasses Area 2 and continues to the Minto East Deposit. Minto East, Area 118 and Area 2 underground mineral reserves will be developed to provide stable production while an additional decline is developed to the Copper Keel zone of MSD. In 2018, a new portal will be developed to extract ore from the Wildfire deposit. Once underground mining of Wildfire is completed, Minto will cease all mining operations if no additional mineral reserves are identified before then.
The LOM production schedule and processing schedule are summarized below:
Phase VI LOM Production Schedule
|Open Pit Stripping Ratio||Waste:Ore||4.75||4.8||4.9||5.8||4.3||4.0||3.7||-||-|
|Total Mined Cu||Mlbs Cu||460||59||82||111||69||58||41||28||14|
|Total Mined Au||koz Au||259||30||39||81||33||29||24||14||9|
|Total Mined Ag||koz Ag||2,256||288||380||576||332||228||229||149||73|
Phase VI LOM Process Production Schedule
|Y E A R|
|Mill Feed Rate||dmt/day||3,750||3,750||3,750||3,750||3,750||3,750||3,750||3,750||3,750||3,750||3,750||3,750|
|Mill Feed Total||Mt||14,393||1,373||1,369||1,369||1,369||1,369||1,369||1,369||1,369||1,369||1,369||654|
|Feed Grade||Cu %||1.53||1.50||1.88||2.29||2.19||1.74||1.70||1.70||1.17||0.74||0.74||0.74|
|Recovery to Conc.||Cu||92%||92%||92%||92%||92%||92%||92%||92%||92%||92%||92%||88%|
|Conc. Grade||% Cu||-||37.0||38.4||41.8||41.2||37.6||37.4||37.4||35.5||32.9||32.9||32.9|
|Conc. Metal||Mlb Cu||444||42||52||63||61||48||47||47||32||21||20||9|
Capital and Operating Costs
The following table reviews capital expenditures without closure costs. The major decrease in capital costs versus the Phase V PSF was due to the continued utilization of Contractor Open Pit mining rather than owner operated. Therefore, purchase of the open pit mobile equipment fleet ($32 million) is avoided. A closure cost allowance of $25 million continued to be reflected in the cash flow analysis, as per an estimation completed in 2010. A sustaining capital cost allowance of $5.6 million is also reflected in the cash flow analysis. Capital expenditures for the life of mine are summarized as follows:
Capital Costs by Major Area
Open Pit Mining
UG equipment (fixed and mobile)
|TOTAL CAPITAL COST||M$||102.7|
The table below presents a summary of the operating costs by major area.
Average Life of Mine Unit Operating Costs by Major Area
Open Pit Mining
|Underground Mining||$/t milled||35.95|
Total Mining (weighted average)
General, administration, camp, royalties
The following table summarizes the economic and production assumptions associated with the Phase VI Pre-feasibility Study:
Phase VI Economic Results
|Open Pit Stripping Ratio||Waste:Ore||4.75|
|Copper millhead grade||% Cu||1.53|
|Gold millhead grade||g/t Au||0.58|
|Silver millhead grade||g/t Ag||5.1|
|Copper in cons||Mlb||444|
|Gold in cons||Oz||188,826|
|Silver in cons||Oz||1,835,613|
|Concentrate Grade||% Cu||Variable by mill feed|
|Gold price (inc. hedging)||US$/oz||300|
|Silver price (inc. hedging)||US$/oz||3.90|
|Unit Total OPEX||C$/t milled||52.69|
|Unit On-site OPEX||C$/lb Cu payable||1.76|
|Unit Off-site OPEX||US$/lb Cu payable||0.29|
|Unit By-product Credit||US$/lb Cu payable||(0.14)|
|Unit OPEX net by-product credits||US$/lb Cu payable||1.92|
|Allowance for closure cost||$M||25|
*Mill Feed includes Ore Stockpile
The following table summarizes the economic key performance indicators associated with the revised pit designs and underground mining that includes the new Cu Keel and Wildfire mineral reserves:
|Before-Tax Cash Flow||After-Tax Cash Flow||Before-Tax NPV8.0%||After-Tax NPV8.0%||After-Tax IRR|
The incremental cash flow that demonstrates the economic benefit associated with underground mining of Cu Keel and Wildfire is:
|Item||Before-Tax Cash Flow||After-Tax Cash Flow||Before-Tax NPV8.0%||After-Tax NPV8.0%||After-Tax IRR|
|Cu Keel / Wildfire||71||35||32||15||31%|
In Yukon, mining projects require an environmental assessment prior to the issuance of significant operating permits for mining, including a Type A Water Use Licence and a Quartz Mining Licence. The Phase IV expansion (2010) has been assessed under the Yukon Environmental and Socioeconomic Assessment Board (YESAB) beginning in August 2010 and the Phase V project YESAB assessment application is partially completed and will be filed in the third quarter of 2012 after updating to include the additional mineral reserves included in the Phase VI PFS. The licensing process is partly complete with the QML issued and the Type A Water Use Licensing application associated with permitting in-pit disposal of the Area 2 tailing has been declared adequate and the public hearing is scheduled for the first week of July 2012. It is anticipated that the amended water use license will follow shortly thereafter.
Following completion of the YESAB evaluation process, subsequent applications to further amend the Quartz Mining License and the Water Use License will support the implementation of the Phase VI mine plan.
Risk and Opportunities
The major risk areas identified in this study are:
- Timing and approval of Phase V and Phase VI WUL permits;
- Exchange rates, metal prices and other external influences;
- The ability to develop the UG mine as per the Phase VI mining schedule and forecasted costs;
- Acquisition of experienced personnel for underground and open pit mining; and
- The ability to maintain minimum dilution through effective grade control practices.
The most important opportunities to improve the project are:
- Optimization of the mine plan;
- Reduce operating costs through continuous improvement initiatives;
- Continued strong demand for copper resulting in sustained high copper prices;
- Discovering new mineral resources and converting them into mineral reserves; and
- As underground mine development advances and costs are sunk there may be opportunities to extract mineral resources not currently considered mineral reserves.
The Phase VI Pre-feasibility study has demonstrated economic justification for Capstone to submit and pursue licence and permit applications to continue with the development of the additional mineral reserves and to continue exploring new targets in the vicinity of the known deposits.
The full Phase VI PFS, prepared as a NI 43-101 compliant Technical Report, will be filed under Capstone's profile on SEDAR at www.sedar.com within 45 days.
Quality Assurance and NI 43-101 Compliance
The technical information in this news release has been prepared in accordance with Canadian regulatory requirements set out in National Instrument 43-101 Standards of Disclosure for Mineral Projects of the Canadian Securities Administrators ("NI 43-101") and reviewed by John Sagman, P. Eng., a "Qualified Person" and Vice President, Technical Services, Capstone Mining Corp. The PFS was prepared with input from the following: Wayne Barnett, Pr.Sci.Nat., SRK Consulting (Canada), Inc., John Eggert, P.Eng, Eggert Engineering Ltd; Bruce Murphy, FSAIMM, SRK Consulting (Canada), Inc.; Bill Hodgson, P.Eng., Genivar Inc.; Garth Kirkham, P. Geo, Kirkham Geosystems Ltd; Michael Levy, PE, SRK Consulting (Canada), Inc.; Brad Mercer, P.Geol. Capstone Mining Corp.; Pooya Mohseni, P.Eng. Minto Exploration; Marek Nowak, P.Eng., SRK Consulting (Canada) Inc.; and Colleen Roche, P.Eng. Capstone Mining Corp. who are responsible for certain sections of the PFS as detailed in the PFS and this release.
In addition, Gregg Bush, Senior Vice President and Chief Operating Officer for Capstone Mining Corp. reviewed and approved this news release.
Cautionary Note Regarding Forward-Looking Information
This document may contain "forward-looking information" within the meaning of Canadian securities legislation and "forward-looking statements" within the meaning of the United States Private Securities Litigation Reform Act of 1995 (collectively, "forward-looking statements"). These forward-looking statements are made as of the date of this document and Capstone Mining Corp. (the "Company") does not intend, and does not assume any obligation, to update these forward-looking statements, except as required under applicable securities legislation.
Forward-looking statements relate to future events or future performance and reflect Company management's expectations or beliefs regarding future events and include, but are not limited to, statements with respect to the estimation of mineral reserves and mineral resources, the realization of mineral reserve estimates, the timing and amount of estimated future production, costs of production, capital expenditures, success of mining operations, environmental risks, unanticipated reclamation expenses, title disputes or claims and limitations on insurance coverage. In certain cases, forward-looking statements can be identified by the use of words such as "plans", "expects" or "does not expect", "is expected", "outlook", "budget", "scheduled", "estimates", "forecasts", "intends", "anticipates" or "does not anticipate", or "believes", or variations of such words and phrases or statements that certain actions, events or results "may", "could", "would", "might" or "will be taken", "occur" or "be achieved" or the negative of these terms or comparable terminology. In this document certain forward-looking statements are identified by words including "scheduled", "guidance", "plan", "planned", "estimated", "projections", "projected" and "expected". By their very nature forward-looking statements involve 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 achievements expressed or implied by the forward-looking statements. Such factors include, among others, risks related to actual results of current exploration activities; changes in project parameters as plans continue to be refined; future prices of mineral resources; possible variations in ore reserves, grade or recovery rates; accidents, dependence on key personnel, labour pool constraints, labour disputes; delays in obtaining governmental approvals or financing or in the completion of development or construction activities; and other risks of the mining industry as well as those factors detailed from time to time in the Company's interim and annual financial statements and management's discussion and analysis of those statements, all of which are filed and available for review on SEDAR at www.sedar.com. Although the Company has attempted to identify important factors that could cause actual actions, events or results to differ materially from those described in forward-looking statements, there may be other factors that cause actions, events or results not to be as anticipated, estimated or intended. There can be no assurance that forward-looking statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, readers should not place undue reliance on forward looking statements.
Alternative Performance Measures
The items marked with a "(1)" are Alternative performance measures and readers should refer to Alternative Performance Measures in the Company's Interim Management's Discussion and Analysis for the three months ended March 31, 2012 as filed on SEDAR and as available on the Company's website for further details.
SOURCE Capstone Mining Corp.