Focus on the environment

At Antofagasta Minerals, we recognise our responsibility towards the environment in which we operate and believe it is possible to mine sustainably by prioritising environmental protection and the efficient use of natural resources.


  • We updated our Biodiversity Standard as part of the implementation of our Climate Change Strategy, improving alignment with the position statement from the International Council on Mining and Metals (ICMM) on mining and protected areas
  • We continued to implement the Global Industry Standard on Tailings Management, which we finished at Los Pelambres and Centinela in August 2023, with work ongoing at our two remaining tailings facilities ahead of a second deadline in August 2025.
  • At the Quillayes tailings storage facility (TSF), Los Pelambres planted a total of 48,000 native trees and shrubs on 60 hectares to control particulate material events while blending the TSF in with its surrounding environment.

Our Environmental Management Model covers leadership, operating risk management, regulatory risk management and reporting of operational events and environmental findings. It seeks to prevent, control and mitigate the impacts we may have on the environment and, if there is an impact, to compensate for it appropriately. In 2022, we focused on regulatory risk, reviewing environmental requirements and auditing our operations both in office and in field. We report our environmental performance monthly to the Executive Committee and twice a year to the Board’s Sustainability and Stakeholder Management Committee.

The Internal Audit area performed environmental audits on all our operations in 2022 to verify their state of compliance with environmental requirements and the measures committed to by our operations, within the framework of their environmental permits. No significant negative findings were reported.


In Chile, large-scale projects are subject to strict environmental and social impact assessments by the Environmental Evaluation Service (SEA) in order to obtain a Resolution of Environmental Approval (RCA). These RCAs include legally binding commitments on matters related to the prevention and mitigation of the project’s impact on the environment and any necessary compensation measures. Compliance with commitments is verified by the Superintendency for the Environment (SMA).

Antofagasta Minerals has a total of 77 RCAs, which include over 10,000 commitments on matters such as water use, air quality, biodiversity and the projects’ construction, operation and closure. In 2022, we obtained no new RCAs. The SEA is currently reviewing the Environmental Impact Assessment (EIA) for the second phase of the Los Pelambres expansion project, which includes doubling the capacity of the desalination plant near Los Vilos to 800 l/s, and the installation of a new concentrate transportation system.


Operational events with environmental consequences are classified as actual (high, medium or low) or potential (high or low) if they could have caused an incident. Actual high or medium severity incidents are investigated by a committee established specifically for this purpose.

Under the criteria established in the environmental assessment of each operation or project, 29 events with no severe environmental consequences were reported to the SMA. Of those events, two were highprofile operational incidents:

  • On 31 May, a leak was detected from the Los Pelambres concentrate pipeline in the Llimpo sector in the Salamanca municipal district. A thorough review detected no material environmental impact and the pipeline resumed operations on 26 June after approval from the relevant local regulator. A review is underway to ensure enhanced safety conditions are incorporated into pipeline operations ahead of the pipeline replacement which has already entered into the government’s Environmental Impact Assessment System (EIA). Information sharing with the community regarding monitoring and inspection of pipeline integrity was agreed, among other measures.
  • On 15 August, unusually high sea swells overturned a construction platform at the marine works of Los Pelambres’ desalination plant project, and marine work was temporarily halted pending the recovery of lost equipment and materials from the seabed. Since the event, to date the SMA-accredited laboratory has found no trace of contamination. The marine works resumed on 4 October and the first stage of the desalination plant is expected to be complete in the first half of 2023.

Further, following a November 2021 incident where runoff from one of Los Pelambres’ emergency tailings pools was detected, in February 2022 we agreed to joint environmental monitoring of these pools with the local Camisas community. After the incident, all of the measurements performed by authorities and the Company in the Camisas estuary ruled out alterations in the water quality.

Further, following a November 2021 incident where runoff from one of Los Pelambres’ emergency tailings pools was detected, in February 2022 we agreed to joint environmental monitoring of these pools with the local Camisas community. After the incident, all of the measurements performed by authorities and the Company in the Camisas estuary ruled out alterations in the water quality.

In 2022, we also submitted updated information to renew our registration with LMEpassport, the sustainability credentials register of the London Metal Exchange (LME), including an executive summary of the Copper Mark which is recognised by the LME.

As members of the International Council on Mining and Metals (ICMM), our four mining sites underwent independent audits to confirm compliance with the ICMM’s Mining Principles Performance Expectations. The assurance process ensures that ICMM’s member companies are being held to the same high standards and will be repeated every three years.

Our mining operations have four tailings storage facilities (TSFs): Los Pelambres’ conventional TSFs at El Mauro and Los Quillayes (no longer in regular use) and a thickened tailings deposit at Centinela. Zaldívar has a small TSF as it produces a small amount of concentrates.

We have an Independent Tailings Review Board for the three main TSFs and their stability and compliance were once again confirmed under international criteria in 2022.

During 2022, we continued with our implementation of the Global Industry Standard on Tailings Management (GISTM), with compliance completed on schedule at Los Pelambres in August 2023, and two years ahead of schedule at Centinela in the same month. The Company’s remaining two facilities: one at Los Pelambres and another at Zaldívar, are due to comply by August 2025 (in accordance with the Standard’s published timeline). In adopting compliance with GISTM, we have strengthened our governance of TSF management and have reinforced our social and environmental controls to comply with the standard’s main focus of zero environmental and social damage. For more information on our compliance with GISTM, please see the section below, including links to our locally hosted websites.

Consistent with the GISTM’s focus on transparency, the El Mauro TSF continued to serve as a pilot for Programa Tranque (Tailings Programme), a public-private initiative managed by Fundación Chile, a Santiago-based technology transfer institute. The initiative seeks to develop an online system for monitoring a TSF’s physical and chemical stability, with an end-goal of applying this monitoring to all TSFs in Chile. The pilot is scheduled for completion in 2023.

We have also improved production rates and compaction of sand in the El Mauro TSF wall. In 2021, rates were approximately 300,000 tonnes per month and in 2022 this was raised to 450,000 tonnes, further increasing the TSF’s stability.

At Centinela’s TSF, we began increasing the height of the raise. This is expected to be completed during the first half of 2024. We also improved the stability of the tailings thickening process, where the percentage of solids sent to the TSF remained above 66%. Each percentage point of solids represents a saving of some 30-40 l/s of water.

We have strengthened risk assessments at all our TSFs based on failure analysis, implementing more detail and critical controls in order to better identify risk and controls to mitigate that risk. We use the ALARP (As Low as Reasonably Practicable) principle to assess the tolerability of risk levels and to communicate this with surrounding communities. Under our process of constant improvement, our TSFs have an extremely low likelihood of failure.

GISTM Standard

Antofagasta’s Mining Division aims to apply industry best practice in the management of its tailings facilities, to protect the safety and care of workers, nearby communities and the environment.

For this reason, the Group is pleased to confirm that both the El Mauro Tailings Dam at Los Pelambres and the Thickened Tailings Deposit at Centinela, meet all the requirements established by a new international standard on tailings facilities, which is known as the Global Industry Standard on Tailings Management (GISTM).

The development of this standard included our participation as members of the International Council on Minerals and Mining (ICMM). It also has the active participation of the United Nations Environment Program (UNEP) and the organization Principles for Responsible Investment (PRI).

In our Mining Division, tailings facilities have always been designed, built and managed in accordance with the most demanding standards and protocols in the industry, which is confirmed by compliance with this new international standard.

In addition to the self-assessment process of the El Mauro Dam (Los Pelambres) and the Thickened Tailings Deposit (Centinela), with these two meeting this new international standard, the Company also has the Quillayes dam (Los Pelambres) and a small tailings facility at Zaldívar. These last two dams have until 2025 to join the GISTM, since they are smaller in size and category, with the review process already underway.

Learn more:

El Mauro (Los Pelambres)

Thickened Tailings Deposit (Centinela)

The waste rock our operations remove in order to extract ore and the spent ore generated by leaching processes are stored in specially prepared dumps at our mine sites. In Chile, the location, operation and closure of these dumps must be authorised by the environmental authorities and the Chilean government’s National Geology and Mining Service (SERNAGEOMIN).

All our operations have robust programmes to control particulate matter (PM10 and 2.5) emissions. They are monitored constantly, in some cases with the participation of the local community. In addition, air quality data is regularly reported to the regional authority, as required.

In 2022, there were no incidents of dust visibility or expressions of concern from nearby communities of Los Pelambres regarding dust from the mine itself or the El Mauro TSF. Coupled with more favourable climatic conditions, this was the result of a series of additional voluntary controls implemented at the TSF. These measures have been verified on site by a committee representing the Caimanes community.

At the Los Pelambres mine, an interdisciplinary working group examined the phenomenon of climate change (including drought and wind pattern intensification) to produce hard data with which to review existing measures and consider others that could be implemented, and to adjust our preventive model accordingly.

At the Quillayes TSF, Los Pelambres planted 48,000 native trees and shrubs on 60 hectares, bringing the total to 120 hectares planted of the 300 hectares planned. The vegetation requires little irrigation, easily adapts to extreme environments and serves to control particulate material events while blending the TSF in with its surroundings.


We approved our new Circular Economy Strategy which will be implemented in 2023. The Strategy has three pillars: reduction in the use of resources, expanding the lifecycle of material and equipment, and conversion of waste into new resources.

The Procurement area will cover issues such as packaging, pallets and the logistics of how goods are transported, as well as the potential reuse of products such as tyres and steel.

In parallel, we have implemented a number of circular economy initiatives. In 2022, Centinela sent to the Colina 1 Penitentiary Centre, in the Metropolitan Region, more than 5,800 kg of wood from operations waste for the inmates to turn the wood into products such as lath panels, pellets for combustion stoves, decorative wooden chips and cutting boards.

Also in 2022, Los Pelambres sent disused mine haulage truck tyres for recycling, using the by-products for the manufacture of steel grinding balls, reincorporating them into the mine’s production process.

In 2020, Centinela launched a project to recycle the high-density polyethylene (HDPE) piping it uses to irrigate its leach pads. Thanks to the adoption of new shredding technology, it is compacted for transport to facilities in Santiago where it is treated to produce the raw material for geosynthetics or, for example, new HDPE products. Antucoya and Zaldívar have also now adopted this model.

As required under Chilean law, all our operations have closure plans approved by SERNAGEOMIN. In addition, we have our own more demanding Integrated Mine Closure Standard. In 2022, we updated this standard to incorporate guidelines from our Biodiversity and Climate Change Standards as well as our Tailings Policy, all of which are aligned with the ICMM’s Integrated Mine Closure - Good Practice Guide.

In 2022, SERNAGEOMIN approved Antucoya’s five-year update of its closure plan and the update of Centinela’s closure plan which incorporates new facilities installed at the operation.

 Read more about our Environment in our Sustainability Report 2022