Protecting water sources in arid North Chile

Collahuasi copper mine is located at high altitude, in an arid area of North Chile's Andean plateau. Water efficiency is a major focus for the operation because it is a scarce resource, essential for the area's biodiversity, and required in large quantities to pump water from deep wells.

Collahuasi reduces its impact on water sources by satisfying 75% of its water requirements with recycled water. Since 2008 it has used a tailings thickener that reduces water use by around 40 litres per tonne, while also bringing additional environmental benefits such as:

• Reducing tailings to a paste-like consistency allows sites to recover and reuse water, cutting their dependence on freshwater;
• Thickened tailings have a smaller volume and are more stable, so the tailings dam can have a smaller surface area and steeper sides; and
• Thicker tailings are less likely to contaminate ground water, since they are largely impermeable.

As a result of efficiency measures, Collahuasi has reduced its extraction of water from a local salt lake by 13% to 780 litres/second. As a result, the flow of a nearby spring has nearly doubled over the past two years.

Xstrata owns 44% of Collahuasi, which is a joint venture with Anglo American and Mitsui. We do not manage the operation directly but Xstrata is represented on its board and executive committee.