Overview
Stage | Permitting |
Mine Type | Open Pit & Underground |
Commodities |
|
Mining Method |
- Longhole open stoping
- Truck & Shovel / Loader
- Cemented rockfill
- Unconsolidated rockfill
|
Mine Life | 11 years (as of Jan 1, 2021) |
Technical Report for a Prefeasibility Study to include an underground mining operation of the Piaba gold deposit at the existing Piaba open pit plus additional open pits at Piaba East, Boa Esperança, Tatajuba and Genipapo. |
Source:
p. 22
Company | Interest | Ownership |
Mineração Aurizona S.A
(operator)
|
100 %
|
Direct
|
Equinox Gold Corp.
|
100 %
|
Indirect
|
Equinox, through its indirect wholly-owned subsidiary Mineração Aurizona S.A. (MASA), owns all surface rights required for the operation of the Aurizona Mine.
Contractors
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Deposit Type
- Breccia pipe / Stockwork
- Vein / narrow vein
- Orogenic
Summary:
The main deposit type in the Aurizona project area is greenstone-hosted orogenic gold, a subtype of the larger orogenic class of gold deposits.
The primary mineralization style on the Property consists of orogenic-style gold deposits, typically associated with the quartz diorite and feldspar quartz diorite units in brittle-ductile structures like the ASZ. Significant gold occurrences in the project area include the Piaba, Boa Esperança, Tatajuba and Genipapo deposits, as well as the Mestre Chico and Micote targets.
Piaba is a structurally-controlled, tabular, orogenic gold deposit with a strike length of ~3.3 km, width of 10 – 50 m, and down-dip extent of at least 700 m, beyond which the deposit is sparsely explored. The deposit is hosted in the brittle-ductile ASZ that is ENE-WSW striking and steeply north dipping to the NNW.
Within the Piaba deposit, the ASZ system is divided into ten shear zones and/or brittle faults, partially segmenting the deposit with limited offsets. The maximum offset observed is 100 m, whereas most offsets are in the order of 10 m. The Pirocaua fault zone at the east-northeast end of the deposit is a significant structure. This brittle fault zone is up to 350 m wide and locally disrupts the Piaba gold zone with a maximum offset of 75 m. At the western end of Piaba on section 1900W there is a northwest striking fault, which truncates the gold zone at depth. Near surface mineralization continues west of the fault in P ........
Mining Methods
- Longhole open stoping
- Truck & Shovel / Loader
- Cemented rockfill
- Unconsolidated rockfill
Summary:
The Aurizona Mine is currently an operating open pit mine with ore processing by gravity concentration and cyanide leach (CIL) circuit which restarted operations in 2018 after three years on care and maintenance. This PFS considers the addition of an underground mine beneath the existing Piaba pit that will assist in extending the mine life to 2032. The additional open pit areas of Tatajuba and Genipapo have been incorporated in the mine plan.
Boa Esperança
Criteria used for the Piaba and Piaba East pits in laterite and saprolite are considered to be relevant and are applied in the Boa Esperança pit design. The Boa Esperança pit is only 52 m deep at its maximum depth which is less than the depth of Piaba and Piaba East, both which have shown stability with the design parameters.
Tatajuba, Genipapo North and South
Geotechnical guidance for the outlying areas of Tatajuba, Genipapo North and South have relied upon the earlier work for Piaba as guidance for the PFS. The majority of Tatajuba is in lateritic and saprolitic material (61%) which is expected to behave in a manner similar to the Piaba pits. The thickness of the laterite and saprolite material totals a maximum of 46 m. The transition and fresh rock account only for 22% and 17% respectively and are predominantly at the east and west extents of the pit with a maximum combined thickness of 65 m. The geotechnical design parameters used at Tatajuba are the same as at Piaba.
Undergro ........
Flow Sheet:
Primary Crushing
ROM is trucked from the open pits and dumped directly into the crusher feed bin or stockpiled on the ROM storage pad and then reclaimed by a front-end loader to the 120 m3 ROM bin. The ore is reclaimed by an apron feeder.
The ROM is fed onto the vibrating grizzly feeder where the screen oversize is directed to the jaw crusher (Metso C120 type with a 160kW motor). The jaw crusher crushes the ore to a P80 of approximately <120 mm. The crushed ore, along with the vibrating screen undersize material, is conveyed to the SAG mill feed surge bin.
Mill Feed System
The SAG mill feed surge bin has a live capacity of 9 minutes (45 m3). The crushed material is reclaimed from the surge bin by an apron feeder onto a belt conveyor to feed the SAG mill. During crusher operation, the surge bin feed rate exceeds the discharge rate, and the feed is diverted from the bin. The diverted ore is conveyed to an emergency stockpile for reclaim by FEL during crusher or ROM feed outages. The crushed ore dead stockpile has 30 hours of storage capacity.
Grinding
The grinding circuit consists of a SAG mill (8.5 m diameter x 4.0 m EGL with a 5,300 kW variable
frequency drive) in open circuit with a small pebble recycle stream and a ball mill (5.5 m diameter x 7.4 m EGL with a 3,800 kW fixed speed drive) in closed circuit with cyclones.
The SAG mill discharge is screened by a short trommel screen that is integrated with the SAG mill. The trommel screen has an opening of 10mm (slot width). Steel balls are manually added into the SAG mill and ball mill on a batch basis as grinding media.
One magnet and one metal detector are provided to remove and detect any metal.
The SAG mill trommel undersize and the product from the ball mill discharges by gravity into the cyclone feed pump box where the slurry is pumped to the cyclones for classification. The cyclone underflow returns to the ball mill, creating a circulating load to the ball mill of approximately 250%. The cyclone overflow with a P80 of 75 µm flows by gravity to the pre-leach thickener prior to subsequent cyanidation treatment. The pulp density of the cyclone overflow is approximately 32% w/w solids.
Dilution water is added to the grinding circuit as required. Lime is added to the SAG mill to maintain a slurry pH of 10.5 or higher.
The grinding mills have 9.1 MW of total installed grinding power providing sufficient power for the duty feed rate at the predicted feed blends in the LOM plan. During times when the feed contains less than 50% of the harder fresh rock material the comminution circuit can handle a higher throughput, up to 10,000 t/d or higher, without sacrificing grind size. A pebble crusher, which was deferred from the original mill upgrade in 2019, is expected to be installed in 2022 to handle an increasing portion of fresh rock.
Flow Sheet:
Summary:
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Projected Production:
Commodity | Units | LOM |
Gold
|
oz
| 1,502,932 |
All production numbers are expressed as metal in doré.
Operational Metrics:
Metrics | |
Daily processing rate
| ...... |
Annual processing rate
| ...... |
Stripping / waste ratio
| ...... |
Waste tonnes, LOM
| ...... |
Ore tonnes mined, LOM
| ...... |
Total tonnes mined, LOM
| ...... |
Tonnes processed, LOM
| ...... |
* According to 2021 study.
Reserves at June 30, 2021:
Mineral Resources are reported using a cut-off grade of 0.30 g/t gold for open pit resources and 1.00 g/t gold for underground resources.
Category | Tonnage | Commodity | Grade | Contained Metal |
Proven
|
16,581 kt
|
Gold
|
1.39 g/t
|
740 koz
|
Probable
|
15,749 kt
|
Gold
|
1.82 g/t
|
920 koz
|
Proven & Probable
|
32,330 kt
|
Gold
|
1.6 g/t
|
1,660 koz
|
Measured & Indicated
|
18,117 kt
|
Gold
|
1.49 g/t
|
868 koz
|
Inferred
|
12,689 kt
|
Gold
|
2.19 g/t
|
895 koz
|
Corporate Filings & Presentations:
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