The Atacama Environmental Assessment Commission has approved the environmental impact study on Gold Fields’ (NYSE: GFI) Salares Norte project in northern Chile — paving the way for the company to proceed with a construction decision in the first half of 2020.
Capital costs for the open-pit project are estimated at US$834 million in a feasibility study completed in late 2018, and the company says it will now update the study and “formulate a funding plan.”
The project is forecast to produce a total of 3.7 million gold-equivalent oz. over an initial 12-year mine life. During its first seven years, the mine is expected to produce 450,000 oz. gold at all-in sustaining costs (AISCs) of US$465 per ounce.
The project contains proven and probable reserves of 3.5 million oz. gold and 39 million oz. silver for 4 million gold-equivalent ounces.
Salares Norte’s two orebodies — Brecha Principal and Agua Amarga — are 500 metres apart. The near-surface mineralization is contained in a high-sulphidation, epithermal system, hosted mainly by a breccia complex along two andesitic and dacitic volcanic domes. Most of the mineralization is oxidized and the sulphide mineralization contains pyrite.
The project is 190 km from the nearest town, Diego de Almagro, and sits in the northern part of Chile’s Maricunga belt at elevations of between 4,200 metres and 4,500 metres.
Gold Fields envisions the mine having a processing plant that includes both carbon-in-leach (CIL) and Merrill-Crowe processes due to the ore’s high silver content. The mine would also use filtered tailings in a dry stack.
The processing plant could deliver recovery rates of about 92% for gold.
Land easement was granted in May 2016 for 30 years, and water rights for the project were obtained in December 2016, with the regulator granting Gold Fields access to 114 litres per second, which is about double what the project needs.
Energy demand is estimated at 12MW, with an independent power producer (IPP) operating an onsite 14MW diesel power station to meet the requirement.