The $63.5m contract also entitles Acciona as the operator of the plant for 20 years.
The initial capacity of the plant will be 17 million liters a day, which could be increased to a maximum of 52 million liters/day.
The construction of the desalination plant is expected to be complete in early 2013.
The plant will be built near the Port of Punto Totoralillo in the Tierra Amarilla area with an objective to meet the water requirements for the mining operations in that area.
Copiapo Valley desalination plant will employ reverse osmosis technology and will be subject to environmental and quality standards.
