Gold Fields is preparing for development ramp up of its Salares Norte gold project in Chile with the main production fleet starting to make its way to site. The Salares Norte main haulage fleet is composed of 18 Caterpillar 191 t class 789D trucks supplied by Finning. Nine of them will be onsite at the mine in March 2021 while the rest will begin to arrive in 2022. The fleet will be operated by mining contractor Ingeniería Civil Vicente (ICV) with the trucks loaded using large hydraulic shovels.
Mine planning is based on open pit mining to exploit the Brecha Principal and Agua Amarga deposits. Production is based on a constant plant throughout rate of 2 Mt/y and peak total material movement of 44 Mt/y. During the LOM, 331 Mt will be mined, consisting of 22.2 Mt of ore to the plant and 308.8 Mt of waste, resulting in a strip ratio of 13.9:1. Prestripping will be some 50.6 Mt. The gold grade averages 4.96 g/t and silver 55.6 g/t.
To improve the project economics, the mine plan is based on an accelerated mining strategy, thus all ore must be stockpiled and re-handled to feed the crusher. This strategy will provide flexibility to manage gold and silver grades for improved gold recoveries, especially during the first years of operations. With this strategy, the mine and plant are decoupled.
Mining will be done on 15 m benches with waste mined in a single pass and ore benches split into three 5 m flitches. Haul roads have a maximum gradient of 10%. Powder factors for blasting vary according to the rock hardness, and powder factors range from 91 g to 149 g of explosives per tonne of rock. Initially, waste will be hauled to the south WSF to build the pad for the plant and TSF. Once the pad is completed waste will be hauled to the north WSF. All ore will be hauled to either the ROM pad or one of the grade-bin stockpiles, from which it will be re-handled to the crusher. ICV will be responsible for hauling the tailings from the plant to the TSF.
The Salares Norte project is the result of more than 20 years of work. The project is located in the Atacama region 180 km northeast of the city of Diego de Almagro and 330 km from the regional capital, Copiapó. It is located between 3,900 and 4,700 m above sea level, in the middle of the highest peaks of the Andes mountain range and the driest desert in the world. Its height and geographical environment are some of the challenges faced by this project that seeks to process the 2 Mt/y of ore in the plant which will use counter-current decantation (CCD), Merrill-Crowe and Carbon-in-Pulp (CIP) processing technology. Construction of the mine is set to be completed in early 2023. Salares Norte has an 11.5 year life of mine with a production average of 350,000 oz/y of gold but this will be up to 450,000 oz/y for the first seven years.
In 2020 some big mineral processing orders for the project were announced. FLSmidth sold three system packages for Salares Norte – a Merrill Crowe plant, an AARL (Anglo American Research Laboratories) elution circuit and a refinery. Separately Metso Outotec is delivering three of its Vertical Plate Pressure Filters with all the ancillary equipment for dry tailings processing as well as one 4 MW SAG mill and one 4 MW ball mill, five thickeners and one clarifier.
Fluor is providing comprehensive engineering, procurement and construction management services for the project with a scope of work including the engineering, procurement of permanent plant material, tendering, award and post-award services for major construction and primary services contracts, as well as construction management and pre-commissioning support. The project will be managed by Fluor’s Santiago, Chile office.
