Gold Fields earlier this year completed a definitive feasibility study (DFS) on its Salares Norte project, in Chile, South America, which enabled the company to declare a maiden reserve for the project.

The company started exploration on the prospect in March 2011, with drilling to date exceeding 140 km.

CEO Nick Holland noted in a webcast presentation this month that the maiden reserve for the project was declared at 21.1-million tonnes, grading 5.1 g/t gold and 57.9 g/t silver for 3.5-million ounces of gold and four-million ounces of gold equivalent.

He said that the project had significant expansion potential that would be explored in future.

The DFS estimated an initial 11.5-year mine life, with production of 450 000 oz/y on average for the first seven years, at an all-in sustaining cost of about $465/oz.

Over the mine life, the all-in cost of the project, which includes the upfront capital, will be $785 per equivalent ounce.

At peak, the project will produce 550 000 oz/y of gold.

The project has an internal rate of return of 25%, with an estimated 2.2-year payback period.

The capital cost estimate was $834-million. Holland said the company would consider a funding strategy in due course, adding that there was an appetite from the South American market to invest in a project like that.

The DFS envisaged an openpit operation with contractor mining and contractor blasting services.

Additionally, the DFS planned for an on-site diesel-generated power station of 14 MW. The company will introduce renewables in stages as the project progresses, with an ultimate target of 20% of power consisting of renewables.

The mine is located more than 100 km away from the electricity grid and, therefore, has to generate its own power.

An environmental-impact assessment has been submitted and Holland expects Gold Fields to obtain approval by mid-2020.

roject engineering is now 35% complete, with construction expected to start in the fourth quarter of 2020, following the granting of an environmental permit.

Americas country manager and project director Max Combes expects first gold from the project in February 2023.

Geology and exploration manager Diego Huete said the project was classified as a high-sulphidation epithermal deposit.

Salares is located along the Maricunga Belt, which has a total endowment of more than 90-million ounces of gold equivalent. It is the first discovery in the northern part of the belt.

Technical manager Francois Swanepoel noted that the mine would be a conventional mining operation, using conventional diesel equipment. A significant stockpiling strategy will be employed.

He expects 308-million tonnes of waste mining over the mine life.

Gold Fields aims to get the prestrip done in under two years (21 months) – by which time the plant would have been commissioned. Gold Fields is targeting a mining rate of 44-million tonnes a year.

The life-of-mine average recovery would be 92.7% gold and 67.5% silver, which was good in terms of a metallurgical perspective, said Swanepoel.

The company would introduce tailings filtration before the tailings were dry-stacked at the tailings facility, located 1 km away from the processing plant. The tailings would be transported hydraulically for filtration, and thereafter transported by truck to the storage facility. Swanepoel said the plant would start with two filters, with a third to be added later on.

The port that will serve the main construction phase is the Port of Angamos, which is 853 km away from Salares; however, closer ports will be used for the export of material.

The mine will use groundwater located 12 km away from the processing plant. The current demand is 30 ℓ a second, while the project has been granted a water right of 114 ℓ a second. The company will eventually install a reverse-osmosis plant.

In terms of water management, the company will monitor 21 wells and 5 points of surface water.

“This is the kind of project that ticks all the boxes in terms of the Gold Fields strategy – a long-life operation, low-cost and in a favourable jurisdiction; it is in a belt that is prospective and contains multimillion-ounce deposits. “The funding strategy is key: the company will decide whether it will go it alone or with a partner, while it considers innovative funding strategies.

“Gold Fields is actively drilling a number of targets in the region; so far [it is] looking encouraging. “There is every reason to believe that we will add to this project. Salares is a first step in a bigger prospect,” concluded Holland.