The Aurizona gold mine is an open-pit improvement in Maranhao, northeastern Brazil.
The mine is absolutely owned by Equinox Gold and has been in manufacturing since 2019. The venture’s feasibility research for the open pit mine was accomplished in July 2017.
Equinox Gold is planning to broaden the mine to incorporate underground mining. A pre-feasibility research for the enlargement of the mine was accomplished in September 2021.
The enlargement is estimated to increase the mine’s life to 11 years, with a mean annual manufacturing of 137,000oz of gold.
Aurizona gold mine location
The Aurizona mine is situated in northeastern Brazil between the cities of Sao Luis and Belemnear. It lies close to Godofredo Viana, Maranhao, and inside 3km of an Atlantic Ocean inlet.
Geology and mineralisation of Aurizona venture
The area surrounding the Aurizona venture is predominantly underpinned by the Paleoproterozoic Sao Luis Craton (SLC) and the Gurupi Belt, that are domestically overlain by Neoproterozoic-Cambrian sedimentary rocks and intersected by early Cambrian dykes.
The mineralisation on the property is characterised by orogenic gold deposits, generally related to quartz diorite and feldspar quartz diorite models inside brittle-ductile buildings.
The gold occurrences throughout the venture space embody the Piaba, Boa Esperança, Tatajuba, and Genipapo deposits, along with the Mestre Chico and Micote prospects.
Reserves at Aurizona mine
The venture is estimated to comprise confirmed and possible reserves of 32.33 million tonnes (mt) grading 1.6g/t gold and 1.66 million ounces (moz) in contained steel, as of September 2021.
Open pit mining technique at Aurizona gold mine
A traditional open-pit mining technique, involving truck and excavator/front-end loaders, is utilized on the Aurizona gold mine.
The mining space consists of 5 open pits: Piaba, Piaba East, Boa Esperança, Tatajuba, and Genipapo. As soon as mining is full, the Boa Esperança pit is slated to be repurposed as a freshwater storage facility.
The design of the ramp accommodates vehicles with an working width of 6.7m, leading to a single-lane entry width of 18.9m and a double-lane width of 25.6m. The general strip ratio is 3.75:1.
The Piaba and Piaba East pits are presently operational, supplying ore to the carbon-in-leach (CIL) processing plant. Piaba East, a single-phase pit, is anticipated to be exhausted by the top of 2024.
Mining operations on the Piaba pit are set to proceed till 2032, overlaying the remaining 4 phases of the design, in addition to the crown pillar on the base, following the completion of underground mining.
Underground enlargement at Aurizona venture
The proposed underground mining might be carried out utilizing longitudinal open-stoping that retreats to central entry.
The mine might be developed alongside a complete strike size of two.3km and can lengthen beneath the Piaba open pit.
Within the location the place stope widths are lower than 8m, longhole open-stoping with everlasting rib pillars might be employed. Conversely, for stopes exceeding 8m in width, longhole open-stoping with cemented rockfill might be utilised.
Entry to the underground mining space beneath the Piaba open pit might be through a portal located in contemporary rock on the pit’s western extremity. The principle ramp is deliberate to be a single decline for the preliminary 735m, the place it is going to intersect with the principle return air flow elevate and the utilidor/emergency exit.
The sub-level spacing might be set at 23m, apart from the 2 ranges located immediately beneath the Piaba open pit, which may have a sub-level spacing of 29.5m. It’s deliberate for underground and open pit mining operations to proceed concurrently.
The underground mining will advance by means of a succession of mining zones, using an overhand sequence. It’s proposed to put in sill pillars between the higher and decrease sections of mining zones 5 and 6, allowing the mining of the higher a part of every zone to start first.
The underground mining fleet will comprise freeway vehicles, drill jumbos, longhole drills, slot elevate borers, and load-haul-dump (LHD) machines.
Ore processing
Run-of-mine (ROM) ore undergoes main crushing in a jaw crusher, after which the crushed ore, together with the undersized materials from the vibrating display, might be transported to the semi-autogenous grinding (SAG) feed surge bin.
The grinding circuit includes a SAG mill and a ball mill, with the previous in open circuit with pebble recycling. The ball mill operates in a closed circuit with cyclones. A gravity focus circuit recovers coarse gold particles from a portion of the cyclone underflow.
The SAG mill discharge is screened and directed to the cyclone feed pump field and additional channelled to pre-leach thickening. The thickener underflow is fed to the CIL circuit.
An automatic Acacia reactor facilitates the leaching of gravity concentrates utilizing a cyanide and sodium hydroxide resolution. Subsequently, the pregnant resolution undergoes remedy within the electrowinning cells.
The carbon loaded with gold is additional processed within the carbon stripping circuit, whereas the leach residue from the ultimate tank is distributed to a carbon security display to reclaim high-quality carbon. The loaded carbon undergoes acid washing and elution, with gold restoration occurring by means of electrowinning.
The ensuing gold sludge is filtered, amalgamated with fluxes, and smelted to provide the ultimate doré bars.
Web site infrastructure
Yr-round street entry is out there from Belem and Sao Luís, the state capital cities of Para and Maranhao, situated 300km due west and 215km south-east of the venture space, respectively. The property is accessed through a repeatedly maintained laterite street, 16km from the city of Godofredo Viana, which is linked by state highways MA-101 and MA-206 to BR-316.
The regional utility, Companhia Energetica do Maranhao (CEMAR), offers a 15MW energy provide through a 69kV overhead energy line to an outside substation situated adjoining to the method plant.
Uncooked water is sourced as reclaimed water from the tailings storage facility (TSF) together with different native freshwater sources.
Contractors concerned
U&M Mineraçao e Construçao was awarded the mining contract for the Aurizona gold mine in March 2018.
Engineering marketing consultant Lycopodium Minerals (Canada) performed the pre-feasibility and feasibility research for the mine.
Mining consultancy corporations SRK Consulting (Canada), BVP Engenharia/Walm Engenharia e Tecnologia Ambiental (BVP/Walm), and AGP Mining Consultants offered enter to Lycopodium for the pre-feasibility research.
The engineering, procurement and development administration (EPCM) contract for the mine was awarded to Ausenco Engineering (Canada).
AGP Mining Marketing consultant, with the assistance of Fairness Exploration Consultants and Knight Piesold, ready the enlargement pre-feasibility research.