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| The Pueblo Viejo mine is one of the largest gold mines in the Dominican Republic |
The Pueblo Viejo mine is one of the largest gold mines in the Dominican Republic. In 2014 Pueblo Viejo mine completed its ramp up and Pueblo Viejo now the only mine in the world with annual production of more than one million ounces of gold (100% basis) at all-in sustaining costs below $700 per ounce for the next three years (2015-2017).
The Pueblo Viejo mine is located in the south of the country in Azua Province, in the Dominican Republic, approximately 100 kilometres northwest of the capital city of Santo Domingo.
In 2009, Pueblo Viejo Dominicana Corporation (PVDC) was formed by Barrick Gold and Goldcorp to develop the Pueblo Viejo mine, Goldcorp holds a 40% interest and Barrick Gold Corporation 60% owning the remaining interest as the mine operator. And the Pueblo Viejo mine began commercial production in January, 2013
Pueblo Viejo mine is one of the largest gold assets in the world, The mine comprises two major oxide deposits known as Monte Negro and Moore and three other small deposits. Moore is the largest deposit and is separated from Monte Negro by 500m of barren mud-stones. With proven and probable gold reserves of 15.53 million ounces.
MINERAL DEPOSIT IN PUEBLO VIEJO MINE
The Pueblo Viejo deposit is epithermal in nature, with the gold deposits being developed from weathering of an underlying funnel shaped, acid sulphate type sulphidic, gold-quartz-pyrophyllite deposit that formed during sedimentation in a small basin of conglomerates, agglomerates, sandstones and carbonaceous sediments representing a maar diatreme complex.
The sulphide ore deposits are present on the upper part of the volcanic and volcaniclastic rocks. The volcanic conglomerates and agglomerates grade upwards to form sand stones and fine grained carbonaceous mud stones.
The deposit contains no mineable vein orebodies, but contains numerous narrow vein like structures that are closely spaced and irregular. These rocks are 120m thick and contain most of the precious metal.
Pyrite and sphalerite are the main sulphide minerals present at the mine. Pyrite constitutes about 10% to 20% of the sulphide mineral. About 70% of pyrite is present locally in veins as well as wall rocks.Traces of sphalerite account for up to 3% with presence limited only to veins.
Pueblo Viejo is developed in the upper part of the Lower Cretaceous Los Ranchos Formation, a series of spilitic and keratophyric volcanics and volcaniclastics on the eastern side of the Cordillera Central on the island of Hispaniola.
A maar diatreme complex in the upper part of the formation was formed in the latter stages of volcanism in this sequence and includes fragmented spilite, re-deposited pyroclastics, quartz eye lapilli tuff and carbonaceous lacustrine sediments.
Primary magmatic minerals have been entirely altered to albite, quartz, calcite, chlorite, illite, smectite, epidote, actinolite and prehnite. The district contains several acid sulphate gold orebodies of which Moore and Monte Negro are the largest.
Two stages of advanced argillic alteration and associated precious metal mineralisation have been identified. Stage one comprises deep alunite, quartz, pyrite and shallower kaolinite, quartz, pyrite, with gold being associated with disseminated pyrite in the wall rock.
Stage two overprinted stage one and produced deep pyrophyllit, diaspore and a shallower, rescrystallised siica cap. Veins of pyrite, sphalerite, energite which formed in response to hydrofracturing of the silica cap have gold grades of up to 100 g/t. Approximately 60% of the gold is in stage one
MINING METHOD IN PUEBLO VIEJO MINE
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| Processing plant at Pueblo Viejo Gold Mine |
Mining method at the Pueblo Viejo mine is a conventional open-pit, The project mine using open-pit mining in stages. Mining is initially being carried out at the Monte Negro deposit. Stripping will not be required as the ore is present near the surface.
Pueblo Viejo mine ore processing involves crushing, grinding, pressure oxidation, counter-current decantation (CCD) washing, carbon-in-leach (CIL), and sulfide precipitation for the recovery of gold, silver, and copper concentrate, and a tailings disposal facility.
Pressure oxidation is done through four autoclaves, each measuring 40m long and 6m wide. Gold is recovered by oxidising the ore for about 60 to 75 minutes at 230°C and 3,450 kilo pascals.
The processing facilities produce per annum up to 1 million ounces of gold; 3.1 million ounces of silver; and 6,100 tonnes of copper. The project also has a limestone / lime facility to support the needs of the process and water treatment plants.
The infrastructure facilities that support operations include a power plant; oxygen plant; truck shop / warehouse facility; administration building; metallurgical assay; environmental laboratories; and camp facilities.
Ore from several different areas of the mine will be mined concurrently and stockpiled according to both gold content and sulphur grade. Ore with a higher gold grade will be mined and processed in the earlier years to benefit project economics.
Pueblo Viejo mine ore processing involves crushing, grinding, pressure oxidation, counter-current decantation (CCD) washing, carbon-in-leach (CIL), and sulfide precipitation for the recovery of gold, silver, and copper concentrate, and a tailings disposal facility.
Pressure oxidation is done through four autoclaves, each measuring 40m long and 6m wide. Gold is recovered by oxidising the ore for about 60 to 75 minutes at 230°C and 3,450 kilo pascals.
The processing facilities produce per annum up to 1 million ounces of gold; 3.1 million ounces of silver; and 6,100 tonnes of copper. The project also has a limestone / lime facility to support the needs of the process and water treatment plants.
The infrastructure facilities that support operations include a power plant; oxygen plant; truck shop / warehouse facility; administration building; metallurgical assay; environmental laboratories; and camp facilities.
Ore from several different areas of the mine will be mined concurrently and stockpiled according to both gold content and sulphur grade. Ore with a higher gold grade will be mined and processed in the earlier years to benefit project economics.
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