The Santa Elena mine project gold and silver deposits form as prominent east–west-trending veins and associated breccias in sub-aerial felsic volcanic rocks. The Santa Elena Main Vein is delineated by drilling along a 1,950 m strike length and 750 m down dip.

Silver and gold mineralization at the Santa Elena mine is hosted in quartz veins and stockworks displaying typical epithermal textures, including banded quartz, vuggy quartz, and brown–black bladed calcite (pseudomorph to quartz) with many of these textures intermixed with hydrothermal breccia.

Other gangue minerals include calcite, adularia, chlorite, and fluorite. Rhodonite has been noted at approximately 530 m vertical depth. Bonanza ore shoots appear to be locally present but have not been delineated in detail. A trend of higher grades and thicker veining is apparent with a plunge of approximately 25° to the east. Up to 200 m of a pyrite and calcite matrix breccia in the hanging wall andesite proximal to the Main Vein has been intersected.

Sulphide abundance is generally low within the veins but can be as much as 5–30%. The sulphides are dominantly pyrite and pyrrhotite with minor galena, sphalerite, and chalcopyrite. Gold occurs typically as native gold, electrum, and silver occurs as electrum, minor acanthite, and rare native silver.

Alteration within the Santa Elena mine deposit is widespread. The volcanic units in the immediate vicinity of the veins exhibit pervasive p ........

The Santa Elena mineral deposits vary in dip, thickness, and geotechnical conditions along strike and dip. Multiple underground mining methods are required to achieve efficient extraction of mineralized material. The mining methods commonly used in the Santa Elena mine are sublevel longhole stoping (Longhole), longhole avoca (Avoca) and Cut-and-Fill. The method assigned to a vein depends on the vein characteristics and rock mass characteristics (for example width, dip, and rock competence, among others). Depending on the selected mining method, the production rate is adjusted to reflect the various productivities.

Longitudinal Longhole
Longitudinal longhole mining is suitable where the dip of the orebody is 45° or greater, and the mineralized material is of sufficient width and grade that the estimated dilution does not eliminate the profitable recovery of the ore. Longitudinal longhole mining consists of an undercut level and an overcut level, each accessed from the main ramp or a transportation drift. Each sill is accessed perpendicular from the ramp, and then developed along strike of the vein to the economic extents of the ore. Once sill development is completed on each level, a longhole rig drills production holes between the sills, which are then blasted in retreating vertical slices until the stoping panel is completed. Stope panel lengths are based on a hydraulic radius calculation considering the geotechnical conditions of the area.

Once th ........

- subscription is required.

Santa Elena has been processing what is known as the Santa Elena blend which consists of high-grade underground mineralized material blended with spent-ore from the existing heap leach pad. The process is based on cyanide tank leaching and MerrillCrowe smelting of fine-ground ore to produce silver–gold doré bars.

The nominal plant capacity is for the processing of 3,000 tpd with the possibility of higher throughput rates depending on ore hardness, targeted final grind, and leaching residence time. Plant throughput averaged 2,500, 2,150 and 2,450 tpd in 2019, 2020 and the first half of 2021, respectively. Plant feed head grades averaged 90 g/t Ag and 1.48 g/t Au from January 2019 to June 2021.

With the introduction of mineralized material from Ermitaño, the plant will continue to process the Santa Elena blend in campaigns alternating with fresh material from Ermitaño. For the achievement of optimum levels of metal recoveries and the corresponding maximum metal p ........