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Gold Fields declares maiden reserve at Salares Norte, targets first gold in 2023 - Mining Weekly

Wednesday, 10 April 2019

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 on Wednesday 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 mentioned 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, on average, 450 000 oz/y 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 this.

The DFS envisaged an openpit operation, with contractormining 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 situated 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 will obtain approval by mid-2020. 

So far, the project’s engineering progress is at 35%, with construction anticipated to start in the fourth quarter of 2020, following the granting of an environmental permit.

Americas country manager and project director MaxCombes anticipated 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, which has been found to be prominent in South America and present in North America.

Salares is located along the Maricunga Belt, which has been declared to have a total endowment of more than 90-million ounces of gold equivalent. Salares 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, with conventional diesel equipment. There will also be a significant stockpiling strategy.

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

Gold Fields aims to get the pre-strip done in under two years (21 months) – by the time the plant is commissioned. GoldFields was targeting a mining rate of 44-million tonnes a year.

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

The company will introduce tailings filtration before it is dry-stacked at the tailings facility, which is 1 km away from the processing plant. The tailings will be transported hydraulically for filtration, and from there on with trucks to the storage facility. Swanepoel said the plant will start with two filters, with a third to be added later on.

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

The mine will use groundwater that is located 12 km away from the processing plant. The current demand is 30 ℓ a second, while the project was 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 of the boxes in terms of the Gold Fields’ strategy; a long-life operation, low-cost, in a favourable jurisdiction, and 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 at 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 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.

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