Desalination and recirculation preserve Chile’s scarcest resource

Mining, Water and Climate Change

October 25, 2024

Image courtesy of RyQ Ingeniería

Desalination has gained traction as a viable solution to counteract the water crisis caused by the country’s 14-year drought. Chile currently has 28 desalination plants either operational or under construction. These facilities have the capacity to produce 8,200 liters per second of fresh water, and projections indicate that this capacity will likely reach 25,000 liters per second by 2028, potentially tripling the current figures if all projects proceed as planned. The growth of desalination projects aligns with Chile's strategic move to diversify its water sources, as freshwater use is projected to decrease to 53% while seawater use will rise to 47% by 2031 in the mining sector.

In March 2024, Antofagasta Minerals inaugurated a US$2 billion desalination plant at Los Pelambres. “The project was substantial, involving approximately 7,000 rotations of direct craft personnel. Our scope included the construction of a desalination plant, a pipeline network extending to the facility, and the establishment of a new concentrator featuring SAG and Ball mills,” said Ailie MacAdam, president of mining and metals at Bechtel, the EPC firm contracted for the project.

Iván Arriagada, CEO of AMSA, provided further insight: “Expansion of the desalination plant to 800 litres per second will substantially reduce the need to extract water from continental sources, which have been impacted by the ongoing drought in the region. Importantly, this will help us advance toward our goal of 90% of water use coming from seawater or recirculated sources.”

The Collahuasi joint venture, the second largest producing copper mine in Chile, will be supplied “through a 194-km, 44-inch pipeline, with five pumping stations and other facilities up to 4,800 meters above sea level. This project is an essential part of Collahuasi’s mine life extension for an extra 20 years,” said Claudio Perillo, president of Andean region Techint Ingeniería y Construcción.

However, “Transporting water from sea level, where desalination plants are, to altitudes of 3,000 or 4,000 m where many mines are located is challenging,” said Juan Castaño, CEO Chile at Amphos 21. “Artificial aquifer recharge, which Amphos 21 has been working on for over 10 years in Europe and Chile, is a solution for excess desalinated water. It helps recover aquifers and maintains a groundwater reserve, benefiting not just the mining sector but also helps restore overall groundwater levels,” he continued.

The adoption of desalination technology is not without financial implications. Desalinization plants require around US$1 billion out of a US$3-4 billion coper project’s CapEx. Furthermore, “The cost of seawater at US$5 per cubic meter is 10 times higher than groundwater at US$0.5, significantly raising operational costs,” said Guzmán.

Yet, many miners will not have a choice. “As desertification progresses and water demands increase, the need for desalination is expected to intensify,” said Víctor Contreras, general manager at Pares&Alvarez.
The state is also making advances to support mining’s endeavors. In March 2024 a Chilean law, Boletín N° 11.608-09, was proposed, aiming to streamline and regulate desalination projects. It designates desalinated water as a public good, establishes a national desalination strategy, updates maritime concession procedures to prioritize human consumption and ecological needs, and mandates environmental impact assessments for all desalination projects.

Much of the state’s support comes from the proactive approach mining operations have taken to avoid social conflicts related to water, said Daniel Caro, general manager at BFS: “An example is the desalination project in Puchuncaví, where a desalination plant will provide water for both a mining company, the community and agriculture. These multipurpose projects, like Anglo American's with Aguas Pacíficos, are pioneering and show how the demand for water in mining and communities can be reconciled.”

Circulate to mitigate
Desalination is the focus for water use but does not entirely solve the problem, said Juan Cariamo Zerené, founding partner and co-CEO at Vantaz: “Mines must also optimize water use internally. Today, mining companies are heavily investing in technologies to optimize and recirculate a significant percentage of water used. The more technology applied; the more water can be recirculated.”

Water recirculation is not smooth sailing: “Water is necessary for many processes in mining, so its quality cannot be understated. The rate of reuse in the mining sector is high, but there is always water that is lost in this recirculation process. Miners must ensure that lost water complies with laws and standards to not bring problems to communities,” emphasized Jerome Poujaud, business development director for Chile & Peru at Veolia.

Howden’s water treatment system helps ensure water quality. Edson Luis Geraldini, the company’s sales director explained: “It injects 80% oxygen into the water, significantly more than the 20% achieved with conventional methods. This technology allows for the rapid recovery of bodies of water such as lagoons and rivers, even eliminating some harmful chemicals... This technology can be particularly useful in northern Chile, where mines face water scarcity, by recycling the water used in mining production and allowing for its reuse in other areas.”
Chile’s multifaceted approach to addressing its water crisis—through legislative support, technological innovation, and strategic investments in desalination and recirculation—illustrates a comprehensive effort to ensure long-term water security and operational stability across sectors.

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