The Fenix Gold Project (16,050 Ha) is located in Atacama Region, in the Copiapo Province - Chile, specifically in the Maricunga Mineral Belt, approximately 160 kilometers northeast of Copiapo by International Road CH-31. It is one of the largest undeveloped pre-feasibility stage gold oxide projects in the Americas.
This is a well-known mining district that contains over 70 million ounces of gold and hosts the La Coipa and Maricunga mines, as well as the Volcan, Caspiche, Lobo Marte and Cerro Casale deposits.
The mineral resource estimate was updated in 2019, based on data collected from 91 diamond drill holes (30,533 m of core) and 291 reverse circulation holes (84,101 m of RC cuttings) which is all the drilling completed on the project between 2010 and 2019. Surface samples (860 two-meter trench samples) have been used for the first time in the resource estimate.
Gold oxide mineralization at the Fenix Gold Project is sub vertical and is of a bulk, disseminated style. It is controlled by NW-SE faulting and the gold mineralization occurs in Black Banded Quartz veins, hosted in complex breccias and bound by fault structures.
Based on the geological features observed, the project is classified as Low Sulphidation type of mineralization. The mineralization is 2,500 m long, up to 600 wide and up to depths of 600 m. The mineralization remains open at depth and to the North East.
Metallurgical studies indicate that gold is usually fine and occurs in both native form and as submicroscopic gold in iron oxides. Gold composition is of high purity which is on average > 99% Au.
The Fenix Gold Project mineralization is comparatively clean with trace occurrences of copper, sulphur and mercury, even at depths of 600m below the surface. This makes the Fenix Gold Project unique in the Maricunga region as it is a pure oxide gold deposit with no transitional or sulphide mineralization.
Several metallurgical testing campaigns have been carried out on the Fenix Gold Project ore since 2010, in order to evaluate its metallurgical behavior in a conventional heap leach process. In addition, some mineralogical studies, in the form of gold deportment, have been conducted to explain the metallurgical results. The test work was undertaken by Kappes, Cassiday and Associates (KCA) and AMTEL Laboratories.
High-grade ore will be crushed to a P80 size 100mm via a single stage Gyratory crusher with lime dosing occurring before the crushed ore is fed to a stockpile. Crushed ore will be re-handled and trucked from the crushed ore stockpile to the leach pad. Agglomeration of crushed ore is not required.
Processing operations will treat the solutions from the heap leach facility operating in a new ADR (adsorption, desorption and refining) plant capable of treating 20,000 tpd of ore to pad or 1,058 cubic meters per hour of pregnant solution to produce doré bars. The plant layout is designed to be upgradeable to 40,000 tpd and 80,000 tpd respectively.
Processing costs are estimated at $4.10 per tonne treated over the current life of mine which includes water purchase and water transport costs.
The leach pad area will be prepared and covered with an impermeable liner. Corrugated, perforated drainage piping will be laid on the liner for collection of the pregnant leach solution. A protective layer of finely crushed, permeable ore will be placed on top of the liner to prevent damage from the mobile equipment and during ore loading. The ore will be stacked on the pad in 10m lifts.
The heap leach pad is located 4 km from the pit, at an elevation of 4,376m above sea level. The pad will be developed in four stages with a stacking volume for Stage 1 of 10.3 Mt; 30.6 Mt for Stage 2; 27.7 Mt for Stage 3 and 60.7 Mt for the final stage. The total pad capacity will be 129 Mt. The irrigation system will uniformly apply cyanide solution directly onto the levelled surface of the leach pile through a drip irrigation system, at an irrigation rate of 10 L/hm2 with an irrigation cycle of 90 days.
The percolation rate through the heap will depend on the viscosity and specific gravity of the solution, the mineral void space, the percentage of fines, mineral affinity for the solution and air entrapment.
Once the heap is saturated, the gold rich solution will drain to the lowest part of the pad and then into the pregnant leach solution (PLS) pond before being pumped to the ADR processing plant.
The power supply for the Project will be generated via diesel generators. Three generators, two in continuous operation and one on standby, will be installed in the power plant located in the ADR plant. There will also be two generators installed at the crusher which will also supply power to the mine workshops.
Grid power is located within 25 km of the mine site and connection to the grid will be considered as the Fenix Gold Mine is expanded.
During Year 1 the mine production rate will be ramped up to 20,000 tpd of high-grade ore (> 0.40 g/t) for estimated gold production of 80,000 oz. The life of mine strip ratio (waste : ore) is estimated to be 0.81 : 1.
Mining will then progress for an additional 12 years at an average annualized rate of 20,000 tpd of high-grade ore and 7,000 tpd of low-grade ore and associated waste material. The high-grade ore will be crushed via a single stage crusher to a P80 size of 100mm and then re-handled and sent to the leach pad whilst the low-grade ore is stockpiled for crushing and leaching in later years of mine life.
Metallurgical test work shows average life of mine recoveries of 75% after single stage crushing to 100 mm, with more than 50% of the gold recovered during the first 45 days of leaching.
Mine design and estimation of the mining reserves was completed using conventional open-pit design methodology. The mine design is based on a $1,225 Lerchs-Grossmann pit optimisation computer analysis.
The pit design incorporates 20m benches made up of 2 x 10m mining benches utilizing a fleet of 70 tonne and 90 tonne excavators and 43 tonne dump trucks. Mining operations will be performed exclusively by a mining contractor under a mining alliance style framework for the entire life of mine.
The 20,000 tpd project requires a water supply of up to 24 L/s. The Fenix Gold Project has access to water via a contract signed with Aguas Chañar S.A. (“Aguas Chañar”), the major water supplier to the town of Copiapo, to supply up to 80 L/s of treated town wastewater from its Piedra Colgada treatment facility located to the north of Copiapo. The original plan, outlined in the 2014 PFS, was to build a pipeline with associated power line from the Aguas Chañar facilities to Fenix Gold along the existing main road, international road CH31, from Copiapo to Argentina which passes within 20 km of the Project. This plan is still being considered for the future expansion of the Project and discussions are ongoing with infrastructure companies who are interested and able to finance and build the pipeline and other mining companies who may wish to share in the benefit of the pipeline project. The capital costs, operating costs and cost of water for the larger water solution are set out in the 2014 PFS.
The water for the 20,000 tpd project will be transported by 30 tonne capacity water tankers, loading from the Aguas Chañar facility and discharging to the process plant located at the Project, a distance of approximately 158 km. The water transport route will be via international road CH31 which passes within 20 km of the mine site.
Water costs are estimated to be $1.56 per tonne of ore processed for the first four years of production and decrease to $1.51 per tonne for the remaining life of the project. The water cost includes the purchase price and transportation of the water to site.
The Company is currently reviewing a number of additional water options involving permitted, unused water rights which are closer to the planned mining operations with the objective of improving the economics of the water supply to the Project.