Efficiency and use of seawater

Water scarcity remains a major challenge for mining operations and a key factor in their relationship with local communities. In view of this, the Group uses seawater in two of its operations and prioritises the efficient use of water in all four of them.


Water management priorities are:

  • Responsible sourcing
  • Efficient usage
  • Pollution prevention

All operations have water management plans based on water balances, as well as water quality and quantity targets. The Group reports its water footprint –the level of consumption per water source– through the Carbon Disclosure Project (CDP) water programme methodology. 

Over the last decade, the effects of climate change have caused a structural deficit in water resources in some regions of Chile with water shortages in several areas, which have led to conflicts among users.


Antofagasta Minerals has been aware of water scarcity since it began operating and has always used this resource carefully. Michilla incorporated the use of seawater into its processes in 1992, followed by Centinela in 2010 and Antucoya in 2015, and the efficient use of water is a constant concern.

Centinela’s expansion project will also operate with seawater, as will the Los Pelambres Incremental Expansion project, although in this case a desalination plant will be built as backup to allow operations to continue unaffected during periods of drought.

The Group reuses the water from its processes to reduce the use of make-up water. The reuse rate is between 71% and 94%, depending on the characteristics of each operation.

In 2016, the Group consumed a total of 55 million m3 of water. This was an increase on the previous year’s consumption due to the incorporation of Zaldivar and Antucoya. Seawater made up 48% of the total water consumed, while the remaining 52% was continental water.

Los Pelambres is the Group’s main user of continental water and has environmental authorisation to use 829 l/s. In 2016, efforts were redoubled, in co-operation with local authorities, communities and central government, in the search for long-term solutions to the water challenges in Choapa province.


1 The 2016 figures include the Antucoya and Zaldívar operations for the first time.

The Group has zero water discharge, with none of its operations discharging water out of any of their facilities.

Water quality is continuously monitored and inspected by the relevant authorities. Los Pelambres performs checks at 160 points and publishes the results of the most relevant monitoring stations on its website.

The community participates in water monitoring activities, and seawater quality is monitored in Los Pelambres’ port as well as at the port that serves the Antucoya and Centinela operations.


In 2016, an innovative project was carried out in collaboration with the University of Chile to improve the treatment of acidic water at the Los Pelambres mine dumps by analysing the feasibility of different technologies and treatment systems. The role of a natural wetland was studied in the treatment of acidic water, and an adsorbent substrate was synthesised which would remove sulphates and other pollutants present in the water. The aim is to develop a comprehensive acidic water treatment system which is sustainable in the long term.