USING SEAWATER TO MINE IN THE WORLD’S DRIEST DESERT

We know that water is a critical resource, that it belongs to everyone, and that it has great social, cultural, environmental and economic importance. It is also essential to mining. Increased demand for water means we must adopt an integrated approach to its management, to ensure that this vital resource remains available to all, both now and in the future.

WHY IS WATER MANAGEMENT IMPORTANT?

Water has been in short supply in Chile and around the world over recent years, making climate change an increasingly pressing issue. It is a valuable resource both for mines and the surrounding environment, and has been a source of conflict with our local communities. It is therefore very important to manage it effectively, extract as little as possible, minimise our impact on natural water sources, recycle it where possible and use it efficiently.

Context 
The ICMM has reviewed the issue of sustainable water use in mining and taken a long-term view. Its Water Stewardship Framework1, published in 2014, recommends good practice for the use of water in mining.

Mining consumes only 3 percent of Chile's water, which is very low compared to 82 percent for the farming sector, 7 percent for manufacturing and 8 percent used for drinking. However, there is a public perception that the mining industry is the country's largest consumer.

According to the OECD's latest environmental evaluation, Chile is already seeing the effects of climate change, which is worsening the structural water deficit. The National Climate Change Plan for 2017 to 20222 forecasts that rainfall will decrease by between 5 and 15 percent by 2030, and droughts will become more frequent.

The extraction, use and disposal of water is regulated by various government bodies, the most important of which is the DGA (the water department). There has been a great deal of controversy over plans to reform Chile's Water Code over recent years. This is being debated by Congress and includes proposals to restrict the use of onshore water by the mining industry.

HOW DO WE MANAGE WATER?

In 2017, the Group began complying with the ICMM's Water Stewardship Framework. This has three key aspects:

  • Involving stakeholders in proactive, inclusive dialogue, characterised by openness and transparency, seeking to understand their priorities, share plans and identify joint solutions. 
  • Focus on the wider water catchment area to understand the social, cultural, economic and environmental importance of water resources, and identify key issues and risks. All of our operations comply with this principle, because their management plans are based on achieving a balance with this broader focus in mind.
  • Efficient water resource management. We have always measured the efficiency of our operations in terms of their impact on water quality. This means managing the extraction, use and discharge of water, evaluating its impact in terms of quantity and quality, maximising its sustainability, maintaining operational flexibility and achieving an economic benefit.

Organisation and reporting
Responsibility for water issues lies with the General Managers of each operation who report on this matter to the Board. The monitoring and reporting processes are carried out by the Corporate Environment department.

We have reported our water footprint to the CDP since 2011. The management and reporting on water issues by our Company is well regarded by international analysts. We are in the third best group, in line with the average of the world’s mining and metals industry.

In 2017, we made progress in bringing each mining operation’s reporting processes into line with the standard and carried out a water risk identification exercise for the mining division as a whole.

USE OF SEAWATER
Antofagasta Minerals has always sought to use seawater in its operations in water-scarce areas. It owns three of the nine desalination plants in Chile. The first was at Michilla, then Centinela and now we have one at Antucoya, which uses raw water without desalination in its hydrometallurgical process. The expansion of Centinela will continue the use of seawater and the expansion of Los Pelambres will use seawater, and as a backup in case of water shortages.

In 2017, 45 percent of the water we used came from the sea. This is well above the mining industry average of 14 percent*. In total, 88 percent of Centinela’s supply was seawater, making it one of the leading mines in this respect.

RECIRCULATION AND WATER EFFICIENCY
Antofagasta Minerals' operations are designed to reuse water and maximise the effectiveness of onshore water usage. The recirculation rate varies between 76 and 93 percent, depending on the characteristics of each operation. In most of our mines, this is above the 75 percent average for Chile's mining industry*.

MINIMISING THE IMPACT ON THE QUALITY AND QUANTITY OF WATER IN THE ENVIRONMENT
Water quality is continuously monitored and inspected by the relevant authorities. Given the environmental context of Los Pelambres, 160 surface and subsurface points are monitored in the Choapa Valley and port areas. In the case of Centinela and Antucoya, each of which are in desert areas far from population centres and agriculture, the underground water extraction points are supervised, as are the port areas. Los Pelambres and Zaldívar are jointly monitored with their local communities, allowing the communities to be involved in the process of sampling water before it is sent for quality analysis by accredited laboratories. In the case of Los Pelambres, this type of monitoring has been carried out since 2011. We are also investing resources in improving drinking water systems in rural areas near to the mine (see box).

The Group does not discharge liquid waste into watercourses.

Monitoring and results
In 2017 we consumed a total of 65,7 million cubic metres of water, 19 percent more than in the previous year. This was mainly due to the increased use of seawater at Centinela with the start-up of the Encuentro Oxides project, and the inclusion of specific accounting concepts from the ICMM’s new water reporting guide3.

45 percent of the water we use is seawater, 28 percent is surface water, 26 percent comes from underground sources and the remaining 2 percent is supplied by third parties. The biggest user of onshore surface and underground water is Los Pelambres, which accounts for 72.1 percent of consumption from these sources.

1 This is available at www.icmm.com/website/publications/ pdfs/water/2014_water-stewardship-framework.pdf
2 The full report is available at http://portal.mma.gob.cl/wp-content/ uploads/2017/07/plan_nacional_climatico_2017_2.pdf
* Source: Minería en números 2017, Consejo Minero.
3 In 2017, we implemented ICMM guideline for consistent water reporting. Factors as retained water in mineral humidity, mine ground water, rainfalls, and continental water (runoff water), were considered.

4 The 2016 and 2017 figures include 100% of the Antucoya and Zaldívar mines, from the date of their construction and acquisition respectively.