The Escondida copper mine is located in the Atacama Desert in northern Chile, one of the driest deserts on the planet. Escondida is the largest copper mine (by production) in the world. It produces over a million tonnes of copper per year, employs more than 3,500 workers and is one of the biggest private single taxpayers in the Chilean economy.
It is not simple to change water sources and to rely solely on one; careful planning and preparation is required. Escondida has been planning a transition away from groundwater resources to desalinated sea water for some time.
The first large-scale desalination plant for industrial use in Chile was commissioned at Escondida in 2006. The plant, designed to produce 525 litres per second, was located in the southern Port of Coloso and included a pipeline of more than 180 kilometres to reach the mining operations located 3,000 meters above sea level in the Altiplano (High Andes).
Escondida commissioned its second desalination plant, Escondida Water Supply (EWS) in 2018. The new facility is one of the largest desalination plants in the world. EWS has a capacity of 2,500 litres per second and includes a twin 40-inch diameter, 180-kilometre pipeline, four high-pressure pumping stations and a reservoir to move water from the Port of Coloso across the Atacama Desert and to the mine site. Additionally, in recognition of the need to reduce the carbon footprint from desalination, the Kelar power generation plant that provides energy to the desalination facility, originally to be coal fired, was redesigned and built as a Liquefied Natural Gas combined cycle plant. The total investment for the new desalination plant was US$3.4 billion.
In 2017, Escondida announced it would cease extraction from one of the main aquifers, Salar de Punta Negra. In 2018, Escondida announced it would also reduce water extraction from the aquifer underlying the Monturaqui wellfield by 54 per cent from FY2020, and that it aspires to cease all groundwater extractions for operational supply by 2030.
Escondida is also working on ways to decrease its overall water consumption. It has promoted initiatives that increase the use of water recovered from its production processes, primarily from the tailings dam, and is investigating technology to reduce overall demand.
The transition to full reliance on desalinated sea water is well underway. This water supply strategy is a milestone in the history of mining in Chile, given the ambition and scale of the desalination projects and the level of investment. The strategy conveys a recognition that groundwater resources are limited and important to communities and the environment, and industry cannot rely on such unique resources in the long term.
While the strategy will have a significant impact on Escondida’s production costs in the near term, we are convinced that today’s challenge is tomorrow’s opportunity. This is key to creating a sustainable future for Escondida.