The Chilean population is in danger: The advance of the toxic mountains, 2,572,263 tonnes every 30 hours in Chile. 

By Javiera Martinez, with assistance from Holly Jones

There are 742 tailings deposits in Chile, with toxic waste containing arsenic, lead, mercury, cyanide salts and chemicals produced in the process of mining accumulating to billions of tonnes. It is estimated that the equivalent to 2,572,263 tonnes of tailings are deposited every 30 hours. It is predicted that by 2026 more than 915 million tonnes will be produced a year, a 74% increase in the creation of tailings compared to 2014, which saw 525 million tonnes a year. These figures place the country as having the third most deposits of this kind in the world, after China and the United States. The highest concentration of these tailings is found in the Coquimbo region. On an international level, in early 2000 the Mining, Minerals and Sustainable Development Project (2002) was already suggesting that, globally, tailings deposit faults were responsible for around 75% of disasters in the mining sector. Chile already has legislation for regulating these toxic waste dumps, however, researchers from the Laboratorio de Sociología Territorial (LST), from the University of Chile, indicate that policy standards need to be raised, given that the poor management of this waste comes with health problems that can be lethal for the exposed population and the environment. 

“We are talking about a problem which is not time bound and is highly complex; a problem which has been around since mining in Chile began many years ago, and which also casts itself into the future. This is why it is such a significant problem”, explains Iván Ojeda, researcher from LST.

Mining consists of the extraction of economically valuable minerals. This process requires separating minerals, chemicals and other compounds resulting from the process. Together these waste products are known as tailings material, and the infrastructure where they are discarded is known as a tailings deposit.

For experts in mining, these structures present two concerns. The first is that there are construction failures which can produce collapses or overflows. The second concerns the chemical stability of the tailings, where acidification reactions need to be minimised and controlled, so that the compounds do not contaminate the surrounding environment. Both concerns are linked to the heavy metals contained in the tailings material, which can be damaging to people’s health and to the ecosystem. Currently, tailings deposits equivalent to 2,572,276 tonnes are dumped every 30 hours in Chile.

These gigantic toxic waste deposits contain arsenic, lead, mercury, cyanide salts and other chemicals produced in the process of mining, together weighing millions of tonnes. The consequences for human life and the environment caused by holding this contaminating material are incalculable.

In the face of this latent threat, the extractive industry has not managed to reconcile its development with that of the communities that live near its projects, or to avoid the collapse of the ecosystem due to faults or accidents.

“Chile is more of an extractive country than a mining country. Australia is a mining country, because it builds infrastructure and institutions that are innovative enough to be able to effectively engage in mining. In Chile the opposite happens. We just extract, but without the infrastructure or the institutions. This is relevant because we have a huge amount of deposits, but we don’t know their current status”, explains Iván Ojeda, graduate in Sociology and Master’s student in Political Science at the University of Chile.

What are the dangers of tailings deposits?

On an international level, in the early 2000s, the Mining, Minerals and Sustainable Development Project (2002) was already suggesting that, globally, tailings deposit faults were responsible for around 75% of disasters in the mining sector.

There is also the risk of contamination of the underground water table from filtration, saturation of the deposits from increased rain, fractures in the reservoirs caused by earthquakes, fissures in the tailings transport ducts between the mine and the deposit due to human error, and constant contamination by particulate matter.

In 2019 another mining industry tragedy hit, this time in Brazil, when a Córrego de Feijao mine tailings dam collapsed in the town of Brumadinho, in the Minas Gerais region. 13 million cubic metres of waste poured out, reaching speeds of 80 kilometres an hour, destroying almost the entire downstream ecosystem and a significant number of towns, leaving the shocking number of 272 people dead – 266 whose bodies have been found and identified and a further 6 whose bodies are still missing.

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Source: Ojeda, I. & Campos-Medina, F. (2021). A socio-territorial approach to the Mining Tailings in Chile: Agglomerations and densities. En Revisión en Environmental Sociology.