TORONTO, ON–(Marketwired – November 22, 2016) – Aura Minerals Inc. (TSX: ORA) (“Aura”, the “Company”) is pleased to announce the results from the Feasibility Study (the “Study”) for the Ernesto/Pau-a-Pique Project (the “Project”) located in the southwest of Mato Grosso state, near Pontes e Lacerda in Brazil.
The Feasibility Study supports a systematic sequence to launch three gold mines starting with the Lavrinha open pit gold deposit, followed by the re-start of the Pau-a-Pique underground gold deposit and subsequently the development and production of the Ernesto underground gold deposit.
Jim Bannantine, the Company’s President and CEO noted, “We believe that the results of the Study show that the Ernesto/Pau-a-Pique Project will help to support Aura Minerals’ operational presence in Brazil for the years to come. The Project is shown to be mostly self-financeable with the selected mining sequence, which will minimize the risks for the Company. We believe the Project has tremendous upside potential as well and we are very encouraged by its prospects.”
BASE CASE OPERATING HIGHLIGHTS AND PROJECT PERFORMANCE:
- Gold price: Baseline economic evaluation: US$1,300/oz Au
- Proven and Probable Mineral Reserves: 2.3 Mt @ 3.16 g/t Au containing 233,600 oz Au
- Average Gold Production: 41,000 oz/year over approximately 5.5 years.
- Foreign Exchange Rate: 3.2:1 (BRA: USD)
- Initial CAPEX: US$17.3 M (Partially funded by the Yamana Debt Facility; including working capital and contingency)
- NPV @ 5% (after tax): US$39.5M
- IRR (after tax): 77%
The Project consists of the Lavrinha open pit, the Pau-a-Pique underground mine and the Ernesto deposit which have been reviewed in the Study; as well as three additional areas to be evaluated in 2017 and 2018 (e.g. Nosde, Japones and Pombihnas).
- The Lavrinha open pit and the Ernesto underground deposit are located approximately 60 kilometre (“km”) south of the Company’s Sao Francisco mine and 12 km south of the town of Pontes e Lacerda. These two deposits are within close proximity to the Project’s processing plant.
- The Pau-a-Pique underground mine has been on care and maintenance since 2014 and is located approximately 47 km south of the Ernesto and Lavrinha deposits and processing plant.
- The three additional areas (Nosde, Japones and Pombihnas) are within 5 km of the processing plant. The plan for the Project is to define and develop these additional areas, in which case mine life would be extended targeting lower operating costs due to higher capacity utilization of Project installed capacity.
The processing plant was commissioned in 2012 and treated ores from Pau-a-Pique and the Ernesto open pit until its closure in December 2014. It is centrally located to these deposits and additional areas and a capacity of 3,000 tonnes per day (“tpd”) through a conventional carbon-in-leach process. The process includes crushing, grinding, gold extraction/recovery and cyanide detoxification stages followed by final deposition in a tailings storage facility.
The Study presents attractive economics since most of the Project’s infrastructure such as fresh water access, power line bringing energy to the different areas in the project (including Pau-a-Pique underground mine) and access roads are already in place. The capital requirements are further reduced by the reutilization and transfer of Pau-a-Pique’s infrastructure and mine fleet to the newly developed Ernesto underground upon completion of the scheduled production at Pau a Pique.
The Study was developed by a group of leading consultants in the mining sector such as P&E Mining Consultants, MCB Brazil, Knight Piesold Canada, Patterson & Cooke, SGS Canada, SGS Belo Horizonte, Jacobs and Tierra Group International Ltd.
FINANCIAL RESULTS (AFTER-TAX)
The Project economics are comprised of two economical scenarios: 1) “Base Case” Scenario which uses current metal prices and foreign exchange rates (e.g. 1,300 USD/oz Au and 3.2:1 FOREX) and, 2) “Consensus” Scenario which considers the long-term metal prices and foreign exchange rates (e.g. 1,350 USD/oz Au and 3.5:1 FOREX). The below summary shows the After-Tax Project economics for the “Base Case” Scenario:
| Operating Statistics | Life-Of-Mine (LOM) | |
| Ore Tonnes | 2,298,000 | |
| Au (g/t) | 3.17 | |
| Plant Recovery (%) | 93.0% | |
| Gold production (payable) oz Au | 217,600 | |
| Cash cost US$/oz | 789 | |
| All-in Sustaining cost US$/oz | 1,086 | |
| Estimated Cash Flows (US$) | (000’s) | |
| Gold Revenue | 282,882 | |
| Government Royalties | (2,829) | |
| Refining and Transport | (3,279) | |
| Net Smelter Return (NSR) | 276,774 | |
| Mining costs | (104,766) | |
| Processing costs | (34,172) | |
| Total Project G&A | (22,449) | |
| Private Royalty | (7,072) | |
| Pre-tax Cash Earnings | 108,315 | |
| Income taxes | (10,554) | |
| PIS/COFINS Credits++ | 10,554 | |
| After-tax Cash Earnings | 108,315 | |
| Capital and Sustaining Capital | (38,946) | |
| Closure Costs | (7,020) | |
| Cash Flow to Entity | 62,349 | |
| Debt Yamana (Including Interest)++ | (9,823) | |
| Cash Flow to Equity | 52,526 | |
| NPV 5% NPV 8% NPV 10% IRR |
39,458 33,385 29,913 77% |
| + | PIS/COFINS are tax credits under Brazilian Tax Regulation for exporters and those can be used to offset against income tax liabilities or refunded in cash. |
| ++ | As previously disclosed, in order to facilitate the acquisition of the Project, the previous owner, Serra da Borda Mineração e Metalurgia S.A. (“SBMM”), a company affiliated with Yamana Gold Inc. (“Yamana”), made available to the Company’s operating entity a working capital facility of up to US$9M (the “Working Capital Facility”). The Working Capital Facility bears interest at 4% per annum on the outstanding balance. The funds advanced from the Working Capital Facility have been invested in the capital, care-and-maintenance and engineering requirements of the Project to restart the Project and to complete the NI 43-101 technical reporting. The Working Capital Facility is expected to be repaid with the initial free cash flow from the Project or will be payable in full by April 30, 2018. Should the Project not enter into production and the Company not have sufficient funds to repay the Working Capital Facility on the due date, such amount outstanding will, at the option of Yamana, be converted into common shares of the Company at a 10% discount over the 20 day VWAP of the Company’s common shares based on the period prior to the due date. At no point in time may Yamana own, beneficially or otherwise, greater than 19.9% of the issued and outstanding common shares of the Company. |
The “Consensus” scenario is considered as an upside case and its results will be presented in the final report, to be filed within 45 days of this news release.
Inflation has not been considered in the cash flow analysis, since the Project will be commenced over a relatively short period of time, and all costs are stated in nominal terms. Neither costs nor revenue has been escalated with any Consumer Price Index (“CPI”) or other base commodities inflation.
ECONOMIC SENSITIVITIES (After Tax)
| US$/oz Au | 1,100 | 1,200 | 1,300 | 1,400 | 1,500 | |||||
| NPV 5% (US$ M) | 3.9 | 21.7 | 39.5 | 57.3 | 75.1 | |||||
| Cashflow to Equity (US$ M) | 9.0 | 30.8 | 52.5 | 74.3 | 96.0 | |||||
| IRR (%) | 11% | 39% | 77% | 130% | 208% | |||||
| % Variance | -20% | -10% | NPV 5% | 10% | 20% | |||||
| CAPEX (US$ M) | 47.1 | 43.3 | 39.5 | 35.6 | 31.8 | |||||
| OPEX (US$ M) | 41.1 | 40.3 | 39.5 | 38.6 | 37.8 | |||||
| % Variance | -20% | -10% | IRR | 10% | 20% | |||||
| CAPEX | 101% | 88% | 77% | 67% | 58% | |||||
| OPEX | 95% | 85% | 77% | 71% | 65% | |||||
MINING
Pau-a-Pique Underground:
Mining at Pau-a-Pique will be conducted by a modified Avoca choke blasting stoping method with ore transported to the run-of-mine (“ROM”) pad on surface by 30 tonne haulage trucks operating through the main ramp. Ore will be subsequently hauled on a 47 km surface road to the Ernesto processing plant. Primary access to the underground mine is via a single portal located next to the main mining office.
Approximately 0.32 Mt of ore at an average grade of 3.24 g/t Au will be mined over a 17 month period at an average of 850 tpd when the Project achieves full production. Once the deposit has been depleted most of the equipment and operators will be transferred to the Ernesto operation.
The stoping method applied to the Area 7 and Area 8, NW, and P3 and P4 ore bodies will be via Hanging Wall (“HW”) access ore drives with levels spaced at 15 metre (“m”) and 21 m vertical intervals, for the upper and lower areas of the deposit, respectively. The upper and lower areas will be separated by a sill pillar. Unconsolidated waste rock will be used to backfill the stopes
The majority of underground mining activities will utilize Aura’s employees, with external contractors or suppliers to undertake the supply of explosives, piping and services, ground support consumables, truck haulage underground and on surface and other specialized tasks (i.e. site security, doré bar transportation, etc.). Aura has 100% ownership of all major fixed plant components utilized at the mine.
Ernesto Underground:
Due to its nature of gentle and variable shallow dip and variable thickness, the Ernesto gold deposit will be extracted by a Drift and Fill mining method, using a combination of drifting in ore and transverse primary and secondary small stopes in a 32%:36%:32% drift/primary/secondary tonnage ratio. The deposit is relatively close to surface at a maximum depth of approximately 170 m and will be accessed by one main ramp portal, with a second portal for definition drilling access.
The main backfill material will be waste rock for secondary stopes and ore drifts and cemented rock fill (“CRF”) for all primary stopes. Waste rock to fulfil the required backfill quantities will be obtained from two sources; the primary source will be from mine waste development and the second source will from the existing Ernesto open pit waste rock storage facility.
A six month pre-production period will be followed by approximately 3.5 years of production to mine an estimated 0.87 Mt of ore at an average grade of 5.03 g/t Au. Production will average 800 tpd.
The majority of underground mining activities at Ernesto will use Aura’s employees, with external contractors or suppliers to undertake the supply of explosives, piping and services, ground support consumables, cement supply for the CRF plant, and other specialised tasks. Aura will have 100% ownership of all major fixed plant components used at Ernesto. Activities such as diamond drilling and other specialized activities or Project work will be contracted.
Lavrinha – Open Pit:
Approximately 1.11 Mt of ore at an average grade of 1.69 g/t Au and 14.0 Mt of waste rock will be mined from the Lavrinha open pit over a two and half year period. The overall strip ratio for Lavrinha is 12.6:1 with mining conducted 365 days per year by a contractor. The contract is full service and includes providing all mining equipment, drilling, blasting, loading, hauling and maintenance. Total material movement rates of the LOM range from 15,000 to 25,000 tpd.
Conventional truck and hydraulic shovels will be utilized. Four excavators, supported by three front-end loaders, will load a fleet of ten 38-tonne trucks and five 25-tonne trucks. Ore will be transported to the primary crusher and ROM pad, and waste material will be hauled to a nearby waste rock storage facility.
METALLURGY
Multiple metallurgical samples of the three deposits (Ernesto, Lavrinha and Pau-a-Pique) were selected from available core and coarse rejects to represent scheduled half years according to the production forecast. The testwork was performed in two different laboratories; SGS Lakefield performed the grinding work, which consisted of SAG Power Index (“SPI”) and Bond Work Index (“BWI”) measurements, while SGS Geosol, in Belo Horizonte Brazil, performed the hydrometallurgical testwork.
The grinding testwork showed the ore to be relatively soft both in the coarse and fine fractions, with SPI averaging 27 minutes and the Bond Work Index (“BWI”) averaging 9.3 kWh/tonne. All samples tested had a calculated treatment rate well above the design rate of 130 t/h (e.g. 3,000 tpd). This indicates that the grinding circuit, as installed, will be able to achieve the planned production rate.
The hydrometallurgical test programme was designed to follow the existing plant flowsheet as closely as possible. Two different grind sizes were investigated, namely 125 microns and 106 microns. On average the gold recovery in the Knelson MD3 laboratory concentrator was higher for the finer grind and averaged 77.78% versus 76.4% for the coarse grind. The gravity concentrate was subsequently intensively leached for 8 and 12 hours, with the 12 hour recovery being substantially better.
The gravity tailings were leached, using a carbon-in-leach (“CIL”) method, to recover the remaining gold and the results indicated that the 24 hour retention time in the plant circuit will be adequate. Overall recoveries, taking into account gravity recovery, intensive leach recovery and CIL recovery, were calculated and averaged 94.7% for the Lavrinha samples and 93.2% for the Pau-a-Pique samples.
The hydrometallurgical testwork on the Ernesto samples is ongoing and thus are not being reported at this time, however, it is anticipated that the metallurgical performance of the Ernesto ore will be similar to the ore coming from Lavrinha and Pau-a-Pique deposits.
PROCESS
The existing gold processing plant is located next to the Ernesto underground deposit and is designed to treat up to 1 million tonnes per year (“Mtpy”) of ore feed. The flowsheet is based on a low-risk proven technology configuration for processing gold bearing ore feed.
A primary crusher is located at the front-end of the process plant. ROM ore feed will be blended and fed through the plant’s primary screen. The screen oversize is crushed and the combined crushed ore feed is ground in a single-stage, closed-circuit Semi-Autogenous Grinding (“SAG”) mill.
Approximately 25% of the mill cyclone underflow feeds a gravity-gold recovery circuit. The grinding circuit product is thickened and subsequently pumped to a leach tank that is followed by six CIL tanks in series. CIL tailings are treated in a cyanide reduction tank where cyanide is chemically decomposed before disposal as tailings. Final tailings are pumped to a nearby tailings storage facility.
Loaded carbon, recovered from the first CIL tank, reports to the desorption area where gold is stripped from the carbon into a solution and electroplated from solution onto stainless steel cathodes. Dried cathode sludge and flux are mixed and smelted to produce gold doré.
CAPITAL COSTS
The development of Pau-a-Pique mine, including the Ernesto process plant and site infrastructure, was effectively completed by the previous owner at the end of 2012. Therefore, the capital cost requirements of the Project are considerably low.
The Lavrinha open pit is a contracted mining operation and the selection of the mining contractor has, after a rigorous competitive bidding process in Brazil, been completed. Therefore, there will not be material capital costs associated with the operation of the Lavrinha open pit.
The Ernesto underground mine will benefit from the transferring of the existing Pau-a-Pique’s mobile fleet and infrastructure since these two deposits have been scheduled sequentially. The Ernesto mine design is compatible with the existing underground mining equipment at Pau-a-Pique.
The existing tailings storage facility will undergo an additional three metre raise to increase its capacity for another two years. The design of this raise was originally done by DAM Engenharia do Brazil and it is currently being re-evaluated and validated by Tierra Group.
Pau-a-Pique Underground Capex:
In late 2014 the Pau-a-Pique mine was placed on care and maintenance. The existing infrastructure and installations are functional and require minimal work before mining recommences.
Sustaining capital expenditure over the mine life includes completion of outstanding work such as:
- Surface maintenance shop upgrades
- Equipment refurbishing mechanical work and associated parts
- Office equipment and existing equipment repairs
- Roads resurfacing (crushed/screen aggregate)
- Small items (i.e. face pumps, fans, electrical distribution boxes).
Total initial and sustaining capital for the LOM is estimated at US$7.8M (Table 1).
| Table 1 Capital Expenditure for Mining LOM at Pau-a-Pique | ||
| Capital Expenditure | Total LOM US$ M | |
| Preproduction | 0.47 | |
| Equipment Rental | 1.11 | |
| Development | 6.19 | |
| TOTAL CAPEX | 7.77 | |
The closure cost for Pau a Pique underground mine has been included in the consolidated cash flow and is estimated at US$1.7M.
Ernesto Underground Capex:
It is anticipated that the development of the Ernesto underground gold mine will commence once the Pau-a-Pique mine’s lateral development has been completed. Within the current evaluation of the Ernesto underground project, additional mobile equipment has been included to achieve the mine production schedule and those units will be purchased/leased.
As per the current mine plan and schedule Ernesto reaches full production after approximately six months from commencement. During this period mining mainly consists of ore development and primary stope extraction. To expedite the planned production the Ernesto underground mine will be accessed via a twin ramp concept, with a Hanging Wall (“HW”) development drift which will be primarily for definition drilling and ventilation, and a main access ramp which will serve as a main haulage and fresh air intake. This arrangement will create a loop for traffic fluidity and will fulfill ventilation and secondary egress requirements.
The total capital cost for Ernesto has been estimated at approximately US$22.97M which includes capitalized development, sustaining capital, allocated labour, and mobile equipment capital for the duration of the mine life. The capitalized development portion has been estimated at approximately US$11.49M which will be required to fully develop the Ernesto underground mine including US$4.53M for pre-production and the remaining US$6.96M as sustaining capital costs required until the mine ceases operation.
The closure cost for the Ernesto underground mine has been included in the consolidated cash flow and was estimated at US$3.0M.
Sustaining capital expenditure for the remainder of the mine life includes:
- CRF surface plant
- Office equipment and existing equipment repairs
- Roads resurfacing (crushed/screen aggregates)
- Replacement of small item i.e. face pumps, fans, electrical distribution boxes
A summary of total capital costs including pre-production and sustaining for the LOM at Ernesto is US$23.0M as outlined in Table 2.
| Table 2 Capital Expenditure for Mining LOM at Ernesto | ||
| Capital Expenditure | Total LOM US$ M | |
| Capital Development Direct Cost | 6.68 | |
| Capital Development Labour | 16.28 | |
| TOTAL CAPEX | 22.97 | |
Lavrinha Open Pit Capex:
The Lavrinha operation is fully contracted and does not incur in any material capital costs. Aura Minerals, using its many years of operating experience in the region, selected a reputable and reliable mining contractor for this operation.
Plant and Tailings Capex:
The gold processing plant was commissioned in 2012 which includes a state-of-the-art distributed control system and all associated instrumentation with all components currently being fully functional.
Lavrinha includes an allowance of US$4.5M for sustaining capital over the 5.5 year LOM.
The existing tailings dam facility has storage capacity for one year of operation and the next dam raise was engineered by DAM Engenharia from Belo Horizonte. The estimated costs for the next raise are US$1.5M and the subsequent raise is estimated at US$2.1M for a total cost of US$3.6M over LOM.
OPERATIONAL COSTS
Pau-a-Pique Underground Opex:
Operating cost estimates have been developed from first principles, utilizing historical advance rates, updated contractual rates for haulage, new consumables quotes and an up-to-date study on Aura’s labour rates. A summary by cost area is presented in Table 3.
| Table 3 Summary of Pau a Pique LOM Operating Cost Estimates | ||||
| Operating Cost Area | US$M | US$ / t ore | ||
| Mining | 16.55 | 57.71 | ||
| Mining Overhead | 2.00 | 6.21 | ||
| TOTAL Operating Cost | 18.55 | 63.92 | ||
Costs of other inputs into the mining operations, including provision of power, water and services, are based on existing contract rates with external suppliers and estimated consumption rates.
Ernesto Underground Opex:
Operating cost first principle estimates have been built utilizing advance rate cycles for each heading that were applied against scheduled quantities. A summary of the Ernesto operating cost estimates is presented in Table 4.
| Table 4 Summary of Ernesto LOM Operating Cost Estimates | ||||
| Operating Cost Area | US$M | US$ / t ore | ||
| Mining | 43.12 | 49.89 | ||
| Mining Overhead | 11.38 | 13.12 | ||
| TOTAL Operating Cost | 54.50 | 63.01 | ||
Ernesto labour costs have been based on scheduled manpower requirements for the operations, in line with Aura’s organizational chart. Salaries and benefit structures are calculated in accordance with current prevailing salary structures in Brazil for the prescribed employment positions. The salary structures and labour rates are compliant with the provisions required under Brazilian tax law. All-in costs have been factored into the labour rates, including bonuses, overtime, sick leave, allowances for vehicle and accommodation (where relevant), annual leave, and health insurance and medical provisions.
Ernesto and Pau-a-Pique mining costs have been developed based on a schedule of first principle developed rates for underground production, development and diamond drilling. Costs of other inputs into the mining operations, including provision of power, water and services, are based on existing contract rates with external suppliers and estimated consumption rates.
Lavrinha Open Pit Opex:
The Lavrinha open pit is a contracted operation and the costs associated with ore production and waste movement have been set as presented in Table 5. Aura Minerals has been actively mining in this area of Brazil for over half a decade utilizing mining contractors.
| Table 5 Summary of LOM Contract Mining Costs for Lavrinha | ||||
| Operating Cost Area | Ore (US$/t) | Waste (US$/t) | ||
| Drilling | 0.38 | 0.22 | ||
| Blasting | 0.40 | 0.30 | ||
| Loading | 0.41 | 0.31 | ||
| Hauling | 0.77 | 0.70 | ||
| Aux. Equipment | 0.20 | 0.20 | ||
| Geology | 0.06 | 0.06 | ||
| Planning | 0.04 | 0.04 | ||
| G&A (Overhead) | 0.06 | 0.06 | ||
| TOTAL Mining Operating Cost | 2.31 | 1.88 | ||
Plant Opex:
The plant operating costs were estimated for different work regimes (i.e. shifts) and using updated quotes for key consumables and historical data.
Process consumables and reagents for the process plant have been calculated on budgeted consumption rates and pricing provided by suppliers for initial first fill supply. Maintenance costs have been estimated on planned maintenance requirements for ongoing operation of the process plant. Gold doré bar freight and refining costs have been based on historical costs and are subject to market adjustment.
Labour costs were defined after a “Pesquisa de Remuneracao e Beneficios” (i.e. Salary survey) was launched by Parametro RH, a Human Resources Company based in Sao Paulo, Brazil in early 2016. This survey provided average, maximum and minimum salaries and benefits for more than 150 employment positions based on eleven active mining companies operating in Brazil.
| Table 6 Summary of Monthly Plant Operating Costs | ||||||
| Only 1 8-hr shift | 2 8-hr Shifts | 3-8hr Shifts | ||||
| Fixed Costs (US$) | ||||||
| Labour Cost | 124,237 | 138,554 | 157,298 | |||
| Contract Cost | 26,483 | 39,747 | 53,142 | |||
| Variable Costs (US$) | ||||||
| Maintenance Cost | 30,439 | 45,658 | 52,446 | |||
| Consumables Cost | 148,413 | 288,388 | 428,457 | |||
| Power Cost | 141,855 | 170,226 | 226,968 | |||
| Other Costs | 23,571 | 34,129 | 45,916 | |||
| Total Cost (US$/t) | 494,998 | 716,702 | 964,226 | |||
| Tonnes Processed | 30,000 | 60,000 | 90,000 | |||
| Unit Plant Cost (US$/t) | 16.50 | 11.95 | 10.71 | |||
The total payable for gold is 99.99% and the refining costs are estimated to be US$5.63/oz of payable gold. The gold transportation costs are estimated at US$9.44/oz of recovered gold (e.g. saleable gold).
Total Project G&A:
In addition to each mine’s G&A, there is a total Project G&A for all general administrative costs that are shared by the three mines. This G&A was estimated as a fixed cost of US$344k per month as long as two mines operate in parallel and US$305k per month when only one mine operates, as shown in Table 7.
| Table 7 Global G&A Costs – EPP Complex | ||||
| Global G&A Costs (US$) | 1 Mine Stand Alone | 2 Mines Operating | ||
| Labour Cost | 117,196 | 134,514 | ||
| Consumables Cost | 8,594 | 10,219 | ||
| Contract Cost | 151,358 | 168,417 | ||
| Others Cost | 27,715 | 31,315 | ||
| Total Cost (US$ per month) | 304,863 | 344,465 | ||
MINERAL RESOURCES
On August 3, 2016 Aura filed an NI 43-101 Mineral Resource Estimate technical report on SEDAR, entitled “Technical Report and Updated Resource Estimate on the EPP Project, Mato Grosso, Brazil”, dated effective May 25, 2016. The report contained the following Mineral Resource statement:
| Table 8 Lavrinha Deposit: Lavrinha Mineral Resource Estimate (1-8) | ||||||
| Resource Category | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Measured | 74,000 | 2.31 | 5,500 | |||
| Indicated | 1,226,000 | 2.25 | 88,700 | |||
| Measured + Indicated | 1,300,000 | 2.25 | 94,200 | |||
| Inferred | 283,000 | 2.51 | 22,800 | |||
- CIM Definitions were followed for Mineral Resources.
- Mineral Resource estimates for the Lavrinha deposit were prepared under the supervision of Marcelo Batelochi, Ausimm (CP 205477).
- Mineral Resources, which are not mineral reserves, do not have demonstrated economic viability. The estimate of Mineral Resources may be materially affected by environmental, permitting, legal, title, taxation, socio-political, marketing, or other relevant issues.
- The quantities and grades of reported Inferred Resources in this estimation is uncertain in nature and there has been insufficient exploration to define these Inferred Resources as Indicated or Measured Mineral Resource and it is uncertain if further exploration will result in upgrading them to the Indicated or Measured Mineral Resource category.
- The mineral resource estimate is based on an optimized pit shell using US$1,300/oz gold and at a cut-off grade of 0.50 g/t gold. Mining costs were considered at US$2.44/t and US$1.89/t for mineralized material and waste haulage, plant processing costs of US$10.24/t and G&A of US$3.8M per year as well as a process recovery of 93%.
- A bulk density model based on rock type was used for volume to tonnes conversion with resources averaging 2.77 tonnes/m3.
- Surface topography as of December 31, 2015.
- Contained metal may not sum due to rounding.
| Table 9 Ernesto Deposit: Ernesto Mineral Resource Estimate (1-10) | ||||||
| Resource Category | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Indicated | 734,000 | 6.70 | 158,200 | |||
| Inferred | 308,000 | 6.30 | 62,400 | |||
- CIM Definitions were followed for Mineral Resources.
- The Qualified Person for this Mineral Resource Estimate is: Richard Routledge M.Sc. (Applied), P.Geo.
- Mineral Resources are estimated from surface and underground diamond drilling and core sampling by conventional 3D block modelling based on wireframing at a 1.5 g/t Au cut-off grade and ordinary kriging grade interpolation.
- For the purpose of resource estimation, assays were capped at 40 g/t Au.
- The mineral resource estimate is based on a cut-off grade of 1.5 g/t Au derived from a Au price: US$1,275 /oz, costs of US$33/t for mining, US$11/t for processing and US$10/t for G&A, as well as a 93% process recovery.
- A bulk density model based on rock type was used for volume to tonnes conversion with resources averaging 2.62 tonnes/m3.
- Mineral Resources are estimated from the 380 m EL to the 96 m EL, or from approximately 50 m depth to 150 m depth from surface.
- Mineral Resources are classified as Indicated and Inferred based on drill hole spacing, interpreted geologic continuity and quality of data.
- Mineral Resources, which are not mineral reserves, do not have demonstrated economic viability. The estimate of Mineral Resources may be materially affected by environmental, permitting, legal, title, taxation, socio-political, marketing, or other relevant issues.
- The quantities and grades of reported Inferred Resources in this estimation is uncertain in nature and there has been insufficient exploration to define these Inferred Resources as Indicated or Measured Mineral Resource and it is uncertain if further exploration will result in upgrading them to the Indicated or Measured Mineral Resource category.
| Table 10 Pau-a-Pique Deposit: Pau-a-Pique Mineral Resource Estimate (1-10) | ||||||
| Resource Category | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Indicated | 519,000 | 4.05 | 67,600 | |||
| Inferred | 117,000 | 4.45 | 16,700 | |||
- CIM Definitions were followed for Mineral Resources.
- The Qualified Person for this Mineral Resource Estimate is: Richard Routledge M.Sc. (Applied), P.Geo.
- Mineral Resources are estimated from surface and underground diamond drilling and core sampling and underground chip sampling by conventional 3D block modelling based on wireframing at a 1.5 g/t Au cut-off grade and ordinary kriging grade interpolation.
- For the purpose of resource estimation, assays were capped at 50 g/t Au and composites >25 g/t Au were restricted to 12.5 m area of influence.
- The mineral resource estimate is based on a cut-off grade of 1.5 g/t Au derived from a Au price: US$1,275 /oz, costs of US$29/t for mining, US$11/t for processing, US$10/t for G&A and US$7/t for mill feed surface transportation, as well as a 93% process recovery.
- A bulk density model based on rock type was used for volume to tonnes conversion with resources averaging 2.77 tonnes/m3.
- Mineral Resources are estimated from the 410 m EL to the 65 m EL, or from approximately 30 m depth to 500 m depth from surface.
- Mineral Resources are classified as Indicated and Inferred based on drill hole spacing, interpreted geologic continuity and quality of data.
- Mineral Resources, which are not mineral reserves, do not have demonstrated economic viability. The estimate of Mineral Resources may be materially affected by environmental, permitting, legal, title, taxation, socio-political, marketing, or other relevant issues.
- The quantities and grades of reported Inferred Resources in this estimation is uncertain in nature and there has been insufficient exploration to define these Inferred Resources as indicated or Measured Mineral Resource and it is uncertain if further exploration will result in upgrading them to the Indicated or Measured Mineral Resource category.
| Table 11 Total Mineral Resource Estimate for the Project | ||||||
| Measured & Indicated Resource | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Lavrinha | 1,300,000 | 2.25 | 94,200 | |||
| Ernesto | 734,000 | 6.70 | 158,200 | |||
| Pau-a-Pique | 519,000 | 4.05 | 67,600 | |||
| Total Measured & Indicated | 2,553,000 | 3.89 | 320,000 | |||
| Inferred Resource | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Lavrinha | 283,000 | 2.51 | 22,800 | |||
| Ernesto | 308,000 | 6.30 | 62,400 | |||
| Pau-a-Pique | 117,000 | 4.45 | 16,700 | |||
| Total Inferred | 708,000 | 4.48 | 101,900 |
| Contained metal may not sum in the above tables due to rounding |
MINERAL RESERVES
Mineral reserves for the Project as of an effective date of July 31, 2016, are as follows:
| Table 12 Lavrinha Deposit: Mineral Reserve Estimate (1-7) | ||||||
| Reserve Category | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Proven | 67,000 | 1.85 | 4,000 | |||
| Probable | 1,043,000 | 1.68 | 56,300 | |||
| Total Proven & Probable | 1,110,000 | 1.69 | 60,300 | |||
- CIM definitions were followed for Mineral Reserves.
- The Mineral Reserves are estimated as of July 31, 2016.
- Mineral Reserve estimates for the Lavrinha deposit were prepared under the supervision of Marcelo Batelochi, Ausimm (CP 205477).
- Mineral Reserves were estimated at cut-off grade of 0.48 g/t Au.
- Lavrinha Mineral Reserves were estimated using an average short-term gold price of US$1,100/oz.
- Bulk density average was 2.78 t/m3.
- Numbers may not sum due to rounding.
| Table 13 Ernesto Deposit: Mineral Reserve Estimate (1-5) | ||||||
| Probable Mineral Reserve Estimate for the “Lower Trap” Portion of the Ernesto Deposit | ||||||
| Reserve Category | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Probable | 868,000 | 5.03 | 140,000 | |||
- The Mineral Reserves are estimated as of July 31, 2016.
- The Mineral Reserve estimate was developed from the resource model prepared by P&E. The Probable Reserves were derived from Indicated Resources.
- The cut-off grade (2.35 g/t Au) was based on a US$1,165/oz gold price, 93% metallurgical Au recovery, 99.99% payable, royalties totalling 3.5%, gold dore bar transport and refining costs totalling US$0.45 / g Au, mine direct and mine indirect costs totalling US$62.41/ t, US$10.30/t processing cost, and US$6.12/t processed for the projected share of the overall multi-mine project G&A cost that would be incurred by the proposed Ernesto underground mine project. The geological continuity of the mineralization was assessed for the cut-off grade.
- The Mineral Reserve tonnage and mined metal have been rounded to reflect the accuracy of the estimate.
- The NI 43-101 Mineral Reserve estimate for the Lower Trap portion of the Ernesto deposit set out in the table above have been reviewed and approved by David Orava, M.Eng., P. Eng., of P&E Mining Consultants Inc., who is a Qualified Person (“QP”) for the purposes of this press release, and who is independent of the issuer.
| Table 14 Pau-a-Pique Deposit: Mineral Reserve Estimate (1-5) | ||||||
| Reserve Category | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Probable | 320,000 | 3.24 | 33,300 | |||
- The Mineral Reserves are estimated as of July 31, 2016.
- The Mineral Reserve estimate was developed from the resource model prepared by P&E. The Probable Reserves were derived from Indicated Resources.
- The cut-off grade (2.40 g/t Au) was based on a US$1,165/oz gold price, 93% metallurgical Au recovery, 99.99% payable, royalties totalling 3.5%, gold dore bar transport and refining costs totalling US$1.56/t, mine direct and mine indirect costs totalling US$58.08/t, US$12.50/t processing cost, and US$6.44/t processed for the projected share of the overall multi-mine project G&A cost that would be incurred by the proposed Pau-a-Pique underground mine project.
- The Mineral Reserve tonnage and mined metal have been rounded to reflect the accuracy of the estimate.
- The NI 43-101 Mineral Reserve estimate for the Pau-a-Pique deposit set out in the table above has been reviewed and approved by Alexandru Veresezan, P. Eng., of P&E Mining Consultants Inc., who is a Qualified Person (“QP”) for the purposes of this press release, and who is independent of the issuer.
| Table 15 Total Mineral Reserve Estimate for the Project | ||||||
| Proven Reserve | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Lavrinha | 67,000 | 1.85 | 4,000 | |||
| Total Proven | 67,000 | 1.85 | 4,000 | |||
| Probable Reserve | Tonnes (t) | Au (g/t) | Contained Au oz | |||
| Lavrinha | 1,043,000 | 1.68 | 56,300 | |||
| Ernesto | 868,000 | 5.03 | 140,000 | |||
| Pau-a-Pique | 320,000 | 3.24 | 33,300 | |||
| Total Probable | 2,231,000 | 3.20 | 229,600 | |||
| Total Proven + Probable | 2,298,000 | 3.16 | 233,600 | |||
| Contained metal may not sum in the above tables due to rounding |
INFRASTRUCTURE
All infrastructure, which includes access roads, power and fresh water were fully built by the previous Project owner and has been preserved.
The Project area is suitable for year-round mining, and has adequate access infrastructure that was developed during the previous 2013-14 operating period. Minor road maintenance work has been identified and will be carried out in late 2016.
Aura is updating the landowner agreements for resumption of ore haulage along an approximate 47 km stretch of the existing access road between Pau-a-Pique and state road BR-174. This process is well underway and no impediments are anticipated.
The Project’s electrical substation is connected to the National grid through a 138kV power line. The Project substation provides 34 kV power (primary voltage) and 13.8 kV (secondary voltage) to the entire project, including the Pau-a-Pique underground mine. The total contracted capacity is 8.0 MW, which is considered sufficient to support the future operation of the Project.
The Company engaged Tierra Group International, an internationally recognized tailings engineering firm, to review the current Tailings Storage Facility’s (“TSF”) design and construction history; and based on the review, design future TSF expansions. The historical review is complete wherein Tierra Group found the existing TSF to have been designed and constructed using satisfactory industry standards of care to support initial operations. Tierra Group is currently advancing a detailed engineering investigation and design to expand the TSF in support of the Study.
ENVIRONMENT & PERMITTING
Aura has existing surface rights over most of the Project area either via direct ownership or agreements with landowners. Negotiations are in process for a remaining parcel in Lavrinha and a small portion of the Pau-a-Pique project area. There are no communities or permanent dwellings within the Project footprint. Just under 234 ha of the Ernesto site’s surface property held by the Company is a designated Legal Reserve, in compliance with the Brazil Forest Code’s provisions pertaining to conservation for native vegetation in rural properties. Maintenance, monitoring and security of the Reserve are the responsibility of the Company.
Additional project disturbance is primarily for Lavrinha mining and waste rock storage is estimated to be in the order of 55 ha. Much of the Lavrinha pit area has been previously affected by smaller scale mining by others.
It is expected that noise, dust and vibration emissions from Project operations will be similar in scale to emissions during the 2013 to 2014 operating period.
Underground mining will utilize both cemented rock fill and non-cemented waste fill in order to optimize ore recovery, and is not expected to generate waste rock for disposal at surface. The backfill process lessens the Project footprint and is also expected to minimize the potential for surface subsidence.
Acid rock characterization studies were conducted by the previous operator using samples consisting of a drillhole interval of mineralization along with the immediately adjacent 1m of non-mineralized material. Three of the 25 Ernesto sample results and three of the 10 Pau-a-Pique sample results indicated potential for acid rock drainage. The Project cost model provides for additional test work in 2017 for tailings and waste rock.
A review of monitoring data indicates that the Company is complying with the monitoring, inspection and surveillance programs stipulated in operating licenses for Ernesto and Pau-a-Pique. Water quality monitoring results indicate that the existing facilities meet or exceed applicable federal effluent and receiving water standards.
Estimated fresh water consumption during the Project’s normal operation is 70.6 m3/h, below the permitted license limit of 100 m3/h from the existing water intake. Approximately 130 m3/h is expected to be recycled from the tailings impoundment to the process plant. Discharges from the Ernesto site include controlled releases of excess tailings impoundment water, in order to maintain sufficient freeboard at all times. These planned releases are expected to occur on an as-required basis throughout the Project life. The Company reports that the most recent impoundment water release occurred from July 8 to August 18, 2016 and totalled 243,242 m3. Water discharges at Pau-a-Pique includes excess water from underground dewatering, and a minor quantity of effluent from its permitted sewage treatment plant.
Project closure costs are estimated at US$6.0M, with an additional US$1.0M allocated for supporting studies. The cost model assumes some closure-related expenditures during the operating period for studies and closure plan updates, as well as for decommissioning of completed mine areas such as the Pau a Pique underground workings. The Ernesto site has a native plant nursery with facilities for seed collection, processing and storage, composting, and propagation of up to 60,000 plants per year.
The Project has the required permits and authorizations to resume and continue mining operations at the Lavrinha open pit and the Pau-a-Pique underground mine, as well as to process ore at the Ernesto plant. Pau-a-Pique had its Mining Concession (Portaria de Lavra) granted on December 27, 2013. The Mining Concession for Lavrinha was requested on August 21, 2016 and is under review by the Nacional de Producao Mineral (“DNPM”), which is expected to be granted soon. While the analysis of the application for the Mining Concession is not concluded, the Project obtained, on September 9, 2016, a special authorization (Guia de Utilização) to mine up to 50,000 t of ore.
This authorization can be renewed for additional 50,000 t of ore before the granting of the definitive Mining Concession. The Project has valid environmental licenses for both Lavrinha and Pau-a-Pique. The permits (Certificados de Registro – CR’s) for use of explosives and chemicals at Ernesto, and for use of explosives at Pau-a-Pique were issued on September 29, 2016.
Once the definitive Mining Concession has been issued, other pending authorizations for continued mining in Lavrinha including its definitive operating license and permit to construct a separate waste rock storage facility adjacent to the open pit, are anticipated to be issued from the State environmental authority.
FINANCING
The Company believes that the selected mining sequence will provide sufficient cashflow to support a majority of the internal financing for the Project. The Company is also considering options with respect to advancing with Project debt to partially fund and accelerate Ernesto through development to production.
OPPORTUNITIES AND NEXT STEPS
The Project has two new areas, Nosde and Japones, for development in 2017 and 2018 which may eventually become replacement open pits once Lavrinha is depleted. There is also a third area (e.g. Pombihnas) and other additional concessions in the area that are currently under exploration.
QUALIFIED PERSONS
The technical information included in this press release has been prepared, reviewed and approved by Fernando A. Cornejo M. Eng., P.Eng. (the Company’s Vice-President, Projects), Eugene Puritch P.Eng. (President, P&E Mining Consultants), Richard Routledge M.Sc., P.Geo., (Sr. Associate Geologist, P&E Mining Consultants Inc.), David Orava M.Eng, P.Eng, (Sr. Associate Mining Engineer, P&E Mining Consultants Inc.), Alexandru Veresezan P.Eng, (Sr. Associate Mining Engineer, P&E Mining Consultants Inc.), Matt Fuller P.Eng. (Tierra Group International Ltd.), Graham Holmes P.Eng. (Snr. Metallurgical Engineer, Jacobs), Diane Lister M.A.Sc., P.Eng. (Altura Environmental Consulting), and Marcelo Batelochi Ausimm, (CP) (Geologist, MCB Consultants).
Cautionary Note
This news release contains certain “forward-looking information” and “forward-looking statements”, as defined in applicable securities laws (collectively, “forward-looking statements”). All statements other than statements of historical fact are forward-looking statements. Forward-looking statements relate to future events or future performance and reflect the Company’s current estimates, predictions, expectations or beliefs regarding future events and include, without limitation, statements with respect to: the Project and the Report (including but not limited to, the mineral resources and mineral reserves). Often, but not always, forward-looking statements may be identified by the use of words such as “expects”, “anticipates”, “plans”, “projects”, “estimates”, “assumes”, “intends”, “strategy”, “goals”, “objectives” or variations thereof or stating that certain actions, events or results “may”, “could”, “would”, “might” or “will” be taken, occur or be achieved, or the negative of any of these terms and similar expressions.
Forward-looking statements are necessarily based upon a number of estimates and assumptions that, while considered reasonable by the Company, are inherently subject to significant business, economic and competitive uncertainties and contingencies. Forward-looking statements in this news release are based upon, without limitation, the following estimates and assumptions: the presence of and continuity of metals at the Project at modeled grades; obtaining and maintaining the various permits required, the capacities of various machinery and equipment; the availability of personnel, machinery and equipment at estimated prices; exchange rates; metals and minerals sales prices; appropriate discount rates; tax rates and royalty rates applicable to the mining operations; cash costs; anticipated mining losses and dilution; metals recovery rates, reasonable contingency requirements; and receipt of regulatory approvals on acceptable terms.
Known and unknown risks, uncertainties and other factors, many of which are beyond the Company’s ability to predict or control could cause actual results to differ materially from those contained in the forward-looking statements. Specific reference is made to the Company’s most recent Annual Information Form and the MD&A for a discussion of some of the factors underlying forward-looking statements, which include, without limitation, gold and certain other commodity price volatility, changes in debt and equity markets, the uncertainties involved in interpreting geological data, increases in costs, environmental compliance and changes in environmental legislation and regulation, interest rate and exchange rate fluctuations, general economic conditions and other risks involved in the mineral exploration and development industry. Readers are cautioned that the foregoing list of factors is not exhaustive of the factors that may affect the forward-looking statements.
All forward-looking statements herein are qualified by this cautionary statement. Accordingly, readers should not place undue reliance on forward-looking statements. The Company undertakes no obligation to update publicly or otherwise revise any forward-looking statements whether as a result of new information or future events or otherwise, except as may be required by law. If the Company does update one or more forward-looking statements, no inference should be drawn that it will make additional updates with respect to those or other forward-looking statements.
For further information, please visit Aura Minerals’ web site at www.auraminerals.com or contact:
Aura Minerals Inc.
Tel: (416) 649-1033
Email: info@auraminerals.com