We are seeking new design, safety and process solutions for the disposal of mining waste by using creativity and innovation, and working with others.

CONTEXT

Chile’s economic and social development is closely connected to mining. One of the consequences of mining is the generation of waste material which is deposited in waste rock dumps, spent ore dumps and tailings storage facilities. There are around 700 tailings storage facilities in Chile of which 124 are in operation.1

Chile’s national geology and mining service SERNAGEOMIN is responsible for inspecting waste disposal facilities, together with other technical bodies – such as the water authority (DGA) - in the regions where mining operations are located. 

We have four tailings storage facilities in operation: two at Los Pelambres, one at Centinela and one at Zaldívar. They have all been designed with high safety standards, constructed using the downstream method, and are regularly monitored by independent, qualified experts. We also participate in international and public-private alliances to strengthen tailings management at local and global level.

MINING WASTE MANAGEMENT

Depending on the copper extraction process, mining generates waste which is deposited in tailings storage facilities, waste rock dumps and spent ore dumps, as well as other industrial waste. Each type of waste is managed in accordance with current regulations and with additional measures to protect the safety and health of people and avoid pollution of the soil, and surface and underground water.

Antucoya, Centinela Cathodes and Zaldívar mainly generate waste in the form of spent ore from their leaching operations while Los Pelambres and Centinela Concentrates generate tailings; in all cases, waste rock dumps are required.

The general manager of each mining operation is responsible for mining waste and reports to the Group’s Board. The corporate environmental department is responsible for controls, monitoring and incident reporting. Since 2015, we have improved communication and warning systems with the community, particularly at the Mauro tailings storage facility.

Tailings storage facilities

Innovation and safety

Innovation has been a priority for Antofagasta Minerals to achieve new and safe forms of storing tailings.

At Centinela, we operate a “thickened” tailings storage facility. This innovation provides significant benefits such as greater physical stability than conventional tailings and enables us to recycle more water to be reused in productive processes.

At Los Pelambres we operate the Mauro and Los Quillayes storage facilities (the latter is used as backup) which were designed to meet the high Chilean safety standards and go beyond these in some aspects of their operation.

In September 2015 the Mauro tailings deposit withstood an 8.3° magnitude earthquake 100 km away, the strongest earthquake in the region in more than 70 years. It suffered no negative impact and continued to operate normally.

Improved standards

Following the 2015 and 2019 tailings dam collapses in Brazil, the mining industry through ICMM reviewed the critical controls for tailings storage facilities. Additional standards were agreed by ICMM members in 2016 to minimise the risk of catastrophic failures of tailings dams and in 2019 an independent review of tailings storage facilities was established. This was co-convened by the ICMM, Principles for Responsible Investment (PRI) and the United Nations Environment Programme (UNEP). The overall objective of this review is to develop an international standard for tailings storage facilities and a report is expected by the end of 2019. In February 2019 the Company made a statement on its tailings storage facilities which can be found here.

Separately, in March 2019 the Church of England pensions Board and the Swedish Council on Ethics for the AP Funds on behalf of a large group of investors sent a letter to nearly 700 listed extractive companies requesting specific disclosure on every tailing facility under their control. The Company’s response to this request can be found here.

Our tailings storage facilities are reviewed twice a year by a group of independent international experts who assess their condition and management, and report directly to the CEO and Board.

Collaborative alliances

As an ICMM member, we support recent proposals to develop an independent, international system of managing tailings deposits. We also actively participate in the ICMM working group on the matter which has two main lines of action:

  • Short term (less than 10 years): Strengthen critical controls for the safe design, operation and closure of conventional tailings deposits (to be developed during 2019) and, within a period of no more than 10 years, significantly improve the management of tailings storage facilities and the implementation of ICMM’s Position Statement on tailings.
  • Long term (10 to 15 years): This involves two lines of work. First to investigate and identify alternative methods of ore recovery to significantly reduce and/or eliminate tailings generation. Second, to promote the development of technologies to eliminate moisture from tailings and thus strengthen their geomechanic properties.

We also participate in the Consejo Minero’s (Mining Council) tailings working group which is focused on facilitating implementation of the ICMM’s Position Statement in Chile and preparing a guide to develop emergency procedures.

Statement on the stability of our tailings dams and deposits

Tailings storage facilities disclosure

Waste rock and spent ore dumps

The waste rock we remove to extract ore and the spent ore we generate through the leaching process are stored in specially prepared areas within our facilities.

In Chile, the location, operation and closure of dumps must be authorised by the environmental authorities and SERNAGEOMIN.

Mining waste
Millions of tonnes
2018 2017 2016
Waste rock 287 274 252
Tailings 96 89 89
Spent ore 63 38 30

 

Industrial waste

Our processes produce hazardous industrial waste, such as used oil and batteries, and non-hazardous waste, such as sludge and timber. All are managed in accordance with legal requirements.  Whenever possible, we recycle waste to avoid its final disposal.

In addition to Chile’s strict existing regulations on waste, Law 20,920 came into force in 2017 which established a waste management framework, extended the responsibility of the producer and promoted recycling, which included tyres as a priority waste.

Non-mining waste
Tonnes
2018 2017 2016
Hazardous industrial 10,015 8,933 6,968
Non-hazardous industrial 27,787 30,822 35,821
Domestic 3,793 3,826 4,493

 

1 Atlas of Tailing Deposits of Chile – Sernageomin, Chile. Available in Spanish at:http://relaves.sernageomin.cl/#/home