The project proposal is the culmination of a process that has seen the company repeatedly sanctioned by environmental authorities related to the pellet plant and requiring the progressive reduction and eventual elimination of the deposition of tailings in the sea, as it has done for the past 40 years, according to the company's 2018 annual report.

In January 2018, the SMA environmental superintendent levelled 20 counts of infringement of environmental norms against the company, including dumping tailings in the sea.

The filtered tailings project would be located 1.5 kilometres from the pellet plant, be comprised of four 10-metre terraces to store 14.6 million tonnes of tailings containing less than 20% moisture content, with an eight-year life.

The Huasco pellet plant was built in 1978 and processes iron ore concentrates into pellets for export. In 2018 it produced 5.9Mt of iron ore in pellets. The overall Huasco operation produced just under half of the 14.5Mt of iron ore CAP produced in 2018.