The challenges to build desalination plants for Chile's mining industry

Chile is mired in a long drought. The country has a rainfall deficit of 60%-80% compared with the historic average and its main reservoirs are hovering around just 30% of their full capacity, according to government data.

Given this situation, a national plan  is underway to promote efficient use of water, which includes desalination plants as a complement to increase potable water supplies. There has been rapid development of these facilities in recent years and the current installed production capacity has surpassed 6,000l/s.

By 2032 that capacity should triple, according to Chilean desalination association Acades.

One of the new desalination projects belongs to the mining company Doña Inés de Collahuasi (CMDIC), with the plant set to be located in Patache port in the Tarapacá region. The initiative is part of a US$3.2bn plan to upgrade infrastructure and increase production capacity.

The contract to build, operate and maintain the desalination plant was awarded to the company Acciona.

To find out about more about the Collahuasi desal project and the challenges facing the segment of the water industry in Chile, BNamericas speaks with Waldo López, business development manager at Acciona Agua.

BNamericas: What are the biggest challenges facing the implementation of desalination plants in Chile?

López: The challenges are similar anywhere in the world, including providing technical, legal, economic and financial viability, which are the basis of any project. In Chile, processing of permits and legal authorizations, such as the marine concession, land use permits, environmental impact studies, sector processing, among others, can take from three to five years. Therefore, the deadlines and programs for the realization of a project are a great challenge to define and, more importantly, to meet.

BNamericas: How do you see the trend in consumption of desalinated water versus continental water for the country's mining operations?

López: Since the first desalination plant for mining was built in 2005 (500l/s) until the present, projects have been developed that have produced installed capacity of 6,200l/s, which confirms the great development that this industry has had in Chile. Projections of water consumption in copper mining, according to Cochilco, indicate that in 2022 some 64% of water used is of continental origin, but 68% of that will be supplied with seawater by 2032. In other words, we will have projects that will increase current water availability by more than 129%.

BNamericas: Does the modification to water rights included in the proposed new constitution mean there is any risk to the proliferation of these projects?

López: The constitutional proposal contains significant changes in water issues, including the creation of the national water agency (ANA), authorizations for usage rights and traditional use in indigenous territories, among others. If the proposed text is approved, much will depend on how the articles are interpreted and how they are put into practice through laws that regulate their operation and the powers [authorities] will have, such as ANA and the water councils created. Regarding whether that represents a risk for desalination projects, we prefer to remain silent, because at Acciona we don't have a political position.

BNamericas: How are investments for desalination plants estimated?

López: The investments depend on many factors, such as production capacity, level of availability, location, etc. Furthermore, the plant is only one part of the supply system. The other part is the transportation system that takes the water to the consumption points, which, at the level of investment (capex) and operating costs (opex) can become more important than the plant itself. We can make a preliminary estimate that the investment for a plant with a water supply system for mining can involve between 15% and 30% of the total investment in the complete system.

BNamericas: Regarding the CMDIC desalination plant. What are the major milestones for the project?  

López: After an intense bidding process, CMDIC selected us to carry out the project through an EPC [engineering, procurement and construction] contract. It is a seawater desalination plant with reverse osmosis technology with a production capacity of 1,050l/s. Once the plant is completed, and after its performance and acceptance tests, Acciona will be in charge of the operation for a period of two years, extendable for another three.

BNamericas: What are the biggest challenges in this CMDIC project?

López: The project is within the 'core' of what Acciona develops. We feel we have the necessary competence and capacity to carry out this great challenge, which implies the development of a plant with a high level of availability, reliability and high efficiency to reduce energy consumption and operating reagents, among other things. We believe that the time we've spent on the initial stages through collaborative work, hand in hand with the client, has allowed us to better identify and address the issues that could generate the greatest concerns in the construction stage.

BNamericas: Some of the solutions offered by Acciona are related to renewable energies. How will the Collahuasi desalination plant be supplied with power?

López: Acciona has two main divisions. One is infrastructure and the other is energy. This project is within the infrastructure framework. The renewable energy division, which has a presence in Chile with 900MW of installed power in the country (including wind and photovoltaic energy), isn't part of the project. CMDIC will supply the energy through contracts that the client will manage privately.

BNamericas: What other desalination plant projects does Acciona have in Chile?

López: We built the Aguas CAP desalination plant, which we currently operate. In addition to the transportation system, two aqueducts totaling more than 200km are included. In the country, we've participated in most of the bidding processes for plants, pumping systems and operation of plants and water transport systems, so the portfolio is broad and is in line with projected water needs.

BNamericas: Do you have other projects aimed at the mining sector?

López: Acciona has extensive experience in carrying out mining works in Chile and Peru. Between 2012 and 2018, the company participated in various works for the conversion of Chuquicamata to an underground operation, through the installation of nearly 25km of ventilation tunnels and 800mt of vertical chimneys.

In 2020, Codelco awarded works to a consortium led by Acciona for the development of infrastructure for the underground Chuquicamata mine, consisting of a series of excavation, fortification and construction works, which include more than 31km of tunnels in the various mine levels and some 40,000m3 of larger excavations.

Also, in the Andean division of Codelco, Acciona participated in the new primary crushing system project where it excavated and fortified the Haulage III tunnel, building 10.5km of tunnels, chimneys, caverns and other underground works.

We're currently executing construction, assembly and infrastructure improvement works for the Pampa Austral tailings deposit, also for Codelco. In Peru, we also built a new tailings pumping system with 12km of pipes for Antamina.