Almaden Minerals reported positive results from the maiden National Instrument (NI) 43-101 compliant Preliminary Economic Assessment (PEA) on its 100% owned Ixtaca Gold-Silver deposit, Mexico.
This deposit is a blind discovery made by the Company in 2010 on claims staked by the Company. The PEA was prepared by Moose Mountain Technical Services ("MMTS") and Knight Piésold Ltd. ("KP").
The conclusions and recommendations of the PEA are that the Ixtaca deposit may be economically viable and the Company should proceed to a Pre-Feasibility study ("PFS"). Highlights of the PEA are summarised below (all values shown are in $US).
It should be noted that this PEA is preliminary in nature as it includes inferred mineral resources which are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves.
There is no certainty that the PEA forecast will be realized or that any of the resources will ever be upgraded to reserves. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability.
Base case (US$1320/oz gold and US$21/oz silver):
Pre-tax Net Present Value ("NPV") of $728M at a 5% discount rate and internal rate of return of 29%;
After-tax (including new Mexican Mining Duties) NPV(5%) of $437M and internal rate of return of 22% ;
Total mill feed of 129M tonnes and 258M tonnes of rock (strip ratio of 2:1)
Mine life of 12.1 years with an average processing rate of 30,000 tonnes per day (10,650,000 tonnes per annum);
Average annual production of 130,000 ounces of gold and 7,798,000 ounces of silver;
Estimated pre-production capital of US$496M. Sustaining capital of US$106M; After-Tax Payback of 4.0 years
The PEA is based on the January 22, 2014 NI 43-101 Compliant Updated Resource Estimate;
The mineral resources incorporated into the mine plan are comprised of 29% Measured, 55% Indicated and 16% Inferred;
In excess of 135,000 meters of core drilling has been completed on the project since the discovery hole was announced by the Company in August, 2010;
Preliminary PEA level metallurgical test work demonstrates high recoveries of both gold and silver from a combination of gravity and bulk flotation concentration, averaging 95%. The PEA considers leaching the flotation combined gravity/flotation concentrates to produce a gold and silver doré on site. Total metal recovery to doré averages 90%
The contribution to the project economics by metal is about 54% from gold and 46% from silver, making Ixtaca a true dual precious metal deposit.
J. D. Poliquin, Chairman of Almaden reported, "We are very pleased with the results of this PEA illustrating the potential economic viability of a mining operation at Ixtaca. The positive base case economics demonstrate how valuable good infrastructure, grade continuity, high recoveries and low-cost mining are to a project. The release of a PEA is a significant milestone for our Company in less than four years from the initial discovery. The PEA highlights the significance of the Ixtaca deposit on a world scale; the projected average annual silver production could make Ixtaca one of the top 20 silver projects in the world. We now look forward to continued exploration progress which may grow Ixtaca as we embark upon a PFS to further de-risk the project and initiate the permitting process."
Economic Results and Sensitivities
A summary of financial outcomes comparing the base case results to two alternative metal price scenarios (both applied to the base case mine plan and processing parameters) are presented below along with a table illustrating sensitivities to various inputs. The base case utilized prices based on a combination of spot prices in 2014 and current common peer usage. The Alternate Case represents the lowest sustained prices of the metals over the last three years. The 3 year trailing average price is shown to represent the upside potential should metal prices regain their previous strength. It is important to note that cohesive and continuous higher grade cores to the Ixtaca deposit could potentially be selectively mined at lower metal prices. Such a scenario is not contemplated in this study but the potential will be presented as an opportunity in the forthcoming PEA report.
Production and Processing
The Ixtaca gold-silver project is planned as an open pit mining operation using contractor mining. Contactor mining operating costs are assumed to be 25% higher than expected owner-operated mining costs. Major mining equipment is comprised of 177-tonne capacity haul trucks with 27m3 shovels.
The estimated mining inventory is comprised of 258M tonnes of rock and 129 million tonnes of mineralized material with an average mill feed grade of 0.422 grams per tonne gold and 25.27 grams per tonne silver. A total of 1.6 million ounces of gold and 94.4 million ounces of silver would be produced over the life of mine.
The PEA includes a 30,000 tonne per day process plant to produce gold and silver doré on site. The process plant includes conventional crushing, grinding, gravity, flotation, vat-leach and Merrill-Crowe extraction process. Average process recoveries for gold and silver are expected to be 90% based on test work carried out at the Blue Coast Research Ltd laboratory in British Columbia, Canada under the supervision of MMTS.
Rock Management, Environment and Community
Almaden recognises the paramount importance of protecting the environment and, to facilitate the development of a sustainable project. Knight Piésold Ltd. ("KP") have been retained to help the Company with long lead item studies concerning environmental monitoring, assessment and permitting matters. Almaden established the following environmental objectives for the Project:
Protect surface and ground water quality;
Incorporate environmental enhancement opportunities into the mine and final reclamation plans;
Minimize the project footprint.
In order to achieve these objectives Almaden and KP have instituted the following management strategies towards the submission of a Mexican Environmental Impact Statement.
Water Management – Almaden with KP has developed a comprehensive 2014 water management strategy including the commencement of a hydrometric and climate monitoring program, and the drilling of water measurement wells. Studies into regional weather patterns suggest that the Ixtaca mine plan will not require water from local aquifers, with the latest modelling indicating that management of rainfall and runoff from within the project area will provide sufficient water for continuous operations.
Currently local communities use existing water supplies that come from natural springs located at higher elevations and upstream of the Ixtaca deposit. Stream flow upstream of the project will be either diverted around or collected, potentially creating a new fresh water supply source for local use, or used for mining and milling processes and before any would be discharged it would be treated to meet environmental guidelines.
Management of Rock – The limestone host rock, which will constitute much of the waste rock of the project, has a high buffering capacity. Static geochemical testing is currently underway to characterize this further.
Environmental Monitoring – Groundwater monitoring to ensure compliance with all applicable best management practice (BMP) technologies is a fundamental component of the Project. Flora and fauna studies are also underway.
Community – The Ixtaca deposit and any potential mining operation will be located in an area previously logged or cleared. Existing land use in the project area is minimal. The Company has employed up to 70 local people in its drilling program who live local to the Ixtaca deposit. Local employees make up virtually all the drilling staff, who have been trained on the job to operate the Company’s wholly owned drills.
The Company has implemented a comprehensive science based and objective community relations and education program for employees and all local stakeholders to transparently explain the exploration program underway as well as the potential impacts and benefits of any possible future mining operation at Ixtaca. The Company regards the local communities to be major stakeholders in the Ixtaca deposit’s future along with the Company’s shareholders.
Every effort is being made to create an open and clear dialogue with our stakeholders to ensure that any possible development scenarios that could evolve from the anticipated future studies are properly understood and communicated throughout the course of the Company’s exploration and development program. The Company invites all interested parties to visit www.almadenminerals.com to find out more about our community development, education and outreach programs.
Economic Impacts – The economic analysis set out in the PEA also provides some possible indications of the potential economic impact of the Ixtaca Project on the local, Puebla State and Mexico economies, should the future work and permitting support development of a mining operation. Highlights include:
Direct employment of more than 400 people during the construction phase and 430 people during the subsequent approximately 12 year operating phase;
Gross investment of approximately over US$163 million in capital equipment and equipment manufacturing during the construction phase, with an additional US$14 million or more during operations; and,
Approximately $434 million in direct taxes to all levels of government, including payments to the local Municipality ($54 million),
Puebla State ($98 million) and Federal ($282 million) governments over the approximately 12 year operating life of the project, but excluding payroll taxes, sales taxes and income taxes paid by employees.
Geology and Mineral Resources
The Ixtaca deposit is an epithermal gold-silver deposit, mostly hosted by veins in carbonate units (calacareous clastic rocks) and crosscutting pre-mineral altered dykes ("basement rocks") with a minor component of disseminated mineralisation hosted in overlying volcanic rocks. Wireframes constraining mineralised domains were constructed based on geologic boundaries defined by mineralisation intensity and host rock type. Higher grade zones occur where there is a greater density of epithermal veining. These higher grade domains have good continuity and are cohesive in nature.
On January 31, 2013 the Company announced a maiden resource on the Ixtaca Zone. Since that time drilling has been focused on expanding and infilling the known resource base for this PEA which utilised the NI 43-101 Compliant Updated Mineral Resource Estimate released January 22, 2014, performed by Gary Giroux, P.Eng., qualified person under the meaning of NI 43-101, and summarised in Table 3 below. The data available for the resource estimation consisted of 423 drill holes assayed for gold and silver. The estimate was constrained by three dimensional solids representing different lithologic and mineralized domains. Of the total drill holes 400 intersected the mineralized solids and were used to make the resource estimate. Capping was completed to reduce the effect of outliers within each domain. Uniform down hole 3 meter (m) composites were produced for each domain and used to produce semi-variograms for each variable. Grades were interpolated into blocks 10 x 10 x 5 m in dimension by Ordinary kriging. Specific gravities were determined for each domain from drill core. Estimated blocks were classified as either Measured, Indicated or Inferred based on drill hole density and grade continuity.
Metallurgical Gold and Silver Test Work
Almaden has previously reported preliminary metallurgical test results (for details consult Almaden’s news release of January 31, 2013 and the 2013 Tuligtic Project NI 43-101 Technical Report filed on SEDAR). These first test results showed that standard gravity and flotation techniques could result in non-optimised gold and silver recoveries that are roughly equivalent for each geological domain. This preliminary test work indicates that leaching the combined gravity/flotation concentrate can produce a gold and silver doré on site. All geologic domains were tested using whole core composites selected to represent a range of grades.
Subsequent to the publication of the preliminary results, in 2013, additional metallurgical work, on the original and new whole core composites, focused on optimizing gravity and rougher flotation results over a broader range of head grades. At present the preliminary test work performed to date indicates overall Au and Ag recoveries from a combination of flotation and gravity concentration and intensive leaching of this combined concentrate to average 90% for Au and Ag across all geologic domains. Further PFS-level metallurgical test work focussing on process optimization is currently underway on existing and fresh domain samples collected from whole drill core. This program will focus on the optimisation of the gravity/bulk flotation/concentrate intensive leaching process with lock cycle cleaner flotation tests and intensive leaching test work on the resulting concentrates. Offsite refining of the concentrates will also be evaluated.