Gold Fields, which has ordered three Metso Vertical Plate Pressure Filters, said water usage is a particularly acute issue at the project due to its location in the Chilean Andes.

"The Salares Norte greenfield project is located 4,500 meters above sea level in the Andean mountains, where water is scarce and needs to be used wisely. To minimise the use of water and improve the physical and chemical stability of our tailings, we have decided to adopt filtered tailings for the project. Salares Norte will be a benchmark plant for dry tailings processing," said Francois Swanepoel, technical manager at Salares Norte.

Metso said the high altitude will require the filters to be semi-assembled in modules to the site.

"The location of the plant at this height … comes with its own unique challenges. For example, the design and transportation of the equipment as well as commissioning needs to be done with special care," said Patricio Mujica Dominguez, senior manager, mining equipment at Metso.

Salares Norte is scheduled to start production in 2023. Gold Fields completed a feasibility study for the project in early 2019 which included a maiden mineral reserve containing 3.5 million ounces of gold and 39.3Moz of silver.

The feasibility study envisages an openpit mining operation with an initial mine life of 11.5 years, producing 450,000oz of gold equivalent per year for the first seven years.