The Chilean authority the Superintendence of the Environment (SMA) completed its investigation against the Alcaparrosa mine of Minera Ojos del Salado, a subsidiary of Lundin Mining, for its operational continuity project that in 2022 caused the generation of a sinkhole 49 meters in diameter and more than 60 m deep, located 900 m from the urban area of Tierra Amarilla, Atacama Region.
The SMA launched an investigation of almost three years into the huge sinkhole, formulating four charges for various breaches committed by the owner.
On Thursday, January 30, the four environmental violations were confirmed, including the overextraction of minerals, unauthorized modifications of infrastructure and other breaches of the project’s environmental permits. The SMA ordered the total and definitive closure of the facilities and operations carried out at the Alcaparrosa mine, in addition to the application of a total fine of US$3.3 million.
Superintendent Marie Claude Plumer explained: “The owner intervened in unauthorized sectors, up to the vicinity of the Copiapó River aquifer, generating a condition of greater water infiltration and the consequent weakening of the rock massif. This determined, in turn, the generation of a sinkhole with a diameter of 49 meters, and a depth of 60 meters.”
“It is important to take into account that the interventions carried out by the company caused irreparable environmental damage to an aquifer that has been classified as scarce and restricted,” said the superintendent. “Project owners are aware of the conditions that are established in their environmental permits to be able to operate. Here, the rules are clear and must be complied with.”
In September 2022, the SMA filed four charges against the owner, which were confirmed as part of the investigation.
The first of them was classified as serious, due to the over-extraction of ore in the Alcaparrosa mine, which is confirmed in the non-compliance with the extraction rate during 2019 (after having extracted 4600 tons per day, exceeding the allowed value of 4300 tpd).
The second charge, classified as very serious, is related to the modification of the authorized mining infrastructure, generating irreparable environmental damage to the aquifer of the Copiapó River. This, due to the modification of the underground drainage system of the Alcaparrosa mine – intended to manage the flow of waters upwelled in the galleries – incorporating underground pools on three levels. In addition, mining infrastructure was executed up to level 350 in the Gaby sector, in an unauthorized sector near the water table of the Copiapó River aquifer.
The third and fourth charges – both classified as minor – are related to the failure to comply with the conditions established for the transport of ore and for having modified the destination of reception of the environmentally evaluated mineral, coming from the mine.
The SMA said the company has 10 working days to pay or 15 days to appeal the decision to the Environment Court.
Lundin’s local unit, Ojos del Salado, said in a statement that it would review the ruling and determine its next steps.
Toronto-based Lundin Mining owns 80% of the Ojos del Salado complex, which has two underground mines: Santos and Alcaparrosa. The remaining 20% is held by Japan’s Sumitomo Metal Mining and Sumitomo Corporation.
The project – classified as environmentally favorable by RCA No. 158/2017 – consisted of extending the useful life of the Alcaparrosa mine operations, giving continuity to the deposit until 2022. Subsequently, a new extension of the useful life of the project was authorized through RCA No. 163/2021, extending its operations and activities until 2025. Under this new authorization, the exploitation of new mineral reserves would be carried out.
Mining operations at Alcaparrosa have been suspended since the incident occurred in 2022. At that time, mineral reserve estimates for the Alcaparrosa mine were removed from the Company’s reserve statement and have not been included in any future production estimates.
The company’s Candelaria operation has been unaffected and generated record production in the second half of 2024. The Candelaria mine is expected to produce between 140,000 and 150,000 tonnes of copper in 2025.
Author: Mayra Flores Ccopa – España | Pan-American Mining