The mine design includes a plant water treatment that can treat acidic runoff from the rain that falls inside the mine, which contributes to reducing the demand for fresh water, while preventing those waters, with a high acidity and red go directly to the rivers in the area.
Through this process Barrick Pueblo Viejo uses only about 0.33% of the total volume of water entering the dam. This is a result of water reuse in processes and the use of acidic runoff water collected.
we can say that the rivers near the mine are recovering its color today. The Margajita, showing a dark side at the time of start of construction of the mine water has higher quality thanks since they began operations.
Water reuse
Harvest
For its geological features, soil in Pueblo Viejo mine has minerals that when in contact with air and rain, react to produce what is known as acid drainage or runoff. Therefore, as part of a plant design collection points (ARD1 and ARD3) to where, by gravity, all falling rain runoff into the reservoir to be reused it is directed contemplated.
It is important to note that these collection points are waterproof, thanks to which one has been installed on clay soil, which does not allow water infiltration, and the other has a plastic membrane on the bottom for any leakage.
In addition to this the water recovered from the tailings dam is also reused.
This dam fulfills a storage function. The resulting of the extraction process, sludge settles in this dam.
Water use
With water harvesting and reuse process, the demand for fresh water in the mine, from the Hatillo Dam is low. To date, Barrick Pueblo Viejo uses less than 1% (about 0.33%) of the annual average volume of water entering the dam.
Treatment
The mine has a Water Treatment Plant, with which ensures that the water is returned to the environment meets national standards.
The water treatment process can be summarized in four steps:
Water is pumped from dams collection acidic waters to the treatment plant where it enters a reactor tank and add limestone, this reduces acidity
The water passes to another reactor where it is stirred continuously, to accelerate the reaction.
The water passes two tanks where quicklime which helps neutralize the pH and in this process the separation of solid starts is added.
4. The last treatment process is water entering the clarifier where a flocculating reagent which causes solids become lumps and precipitate faster added.
The clarifier is designed with a double wall, which allows the separation of the treated water and the precipitated solids are then sent to the tailings dam.
Discharge
As a result of the treatment process, the water is returned environment in compliance with national standards. The process and water quality are continuously monitored. In such verification it is further included the quarterly participation of communities that are trained in the use of measuring instruments water quality.
The most tangible result of the quality of water discharged from the mine in Pueblo Viejo is the improvement presented by the Margajita (our only point of discharge of industrial effluents) river. Due to the treatment system that exists in the operation of Barrick Pueblo Viejo now the story is very different, water is clearer and has an adequate level of acidity, aquatic life returning to normal.
