Deposit Type
Tantahuatay is a high-sulfidation epithermal deposit. It presents Au-Ag mineralization in oxides, which are associated with silicified breccias that present mainly silica alteration. Below the oxide level, there is a predominant Cu mineralization with the presence of As, and in smaller quantities, covellite and supergene chalcocite.

The current Tantahuatay open pit (TH1 and TH2) mines Au mineralization within high-sulfidation epithermal alteration and mineralization structures comprising silicified breccias with extensive silica alteration, and laterally grading to pervasive silicification and local alteration of marginal silica alunite. Enargite mineralization is locally discernible within the vughs in the pit and undoubtedly contributed to the high FeO content, becoming more evident below the oxidation base. Wall rocks in the open pit and drill holes consist of volcanic andesite, a subvolcanic andesite dome and a prealteration porphyry with stockwork veins, all showing predominant silica pyrophyllite alteration varying to silica-alunite in the uppermost portions. Fracture-controlled enargite-pyrite mineralization cuts the pyrophyllite alteration in the volcanic rocks and porphyry, as well as quartz stockwork veins, so the porphyry must predate the pervasive pyrophyllite alteration and also the epithermal event. The presence of dickite instead of the usual alunite deposited with enargite is indicative of a lower temperature high-sulfidation epith ........

Coimolache mining company operates the Tantahuatay mine and has planned extract ore, throughout the life of mine, of 5 zones by open pit mining method, that is, the surface mining of economic ore. For this purpose, open pits are designed considering geotechnical parameters, which are inherent to the rock mass quality and ensure the stability of pit slopes. Design parameters are established by sectors and the configuration of double or single bench, bench height, berm length, inter-ramp angle and bench face angle are defined for each sector.

The distribution of open pits throughout the life of mine and these are: Tantahuatay 2 (THY2), Tantahuatay 2 NW extension (THY2 NW Ext. ), Mirador Norte (MN), Mirador Sur (MS), and Cienaga Norte (CN).

Production schedule
The production schedule established over the life of mine (LOM plan) considers the ore production from Tantahuatay 2 (THY2), Tantahuatay Northwest Extension (THY2 NW Ext), Mirador Norte (MN), Mirador Sur (MS), and Cienaga Norte (CN).

The strip ratio of the LOM plan is 0.34, i.e., on average over the life of the mine 0.34 tons of waste rock will be mined to expose and extract one ton of ore.

Reported ore reserves total 65.45 Mt with an average grade of 0.30 g/t Au and 8.42 g/t Ag. On the other hand, the reported waste will total 22.03 Mt. The LOM mining plan will be developed over a period of 6 years.

A total of 469.8 koz Au and 3,054.9 koz Ag are planned to be pr ........

Coimolache operates a run-off-mine (ROM) leaching operation that processes gold and silver rich ores to produce dore bars assaying above 90% precious metals.

The open pit mining operation uses haultrucks to deliver ROM ore to two leaching pads, namely Tantahuatay and Cienaga distant approximately one kilometer from each other. The Tantahuatay leach pad receives ore from multiple open pits including: Tantahuatay 2, Tantahuatay 2 North-West Extension, Tantahuatay 5, Mirador Sur, Mirador Norte. The Cienaga leach pad receives ore mainly from Cienaga Norte open pit.

Once haultrucks dump their ore load in the leach cell a backhoe adds powder calcium oxide (or CaO), then a bulldozer starts spreading the material in 8-meter high lifts. The surface area of a leaching cell varies with a number of factors, but typically ranges between 2,500 m² up to 5,000 m².

In the Tantahuatay leach pad, the percolating solution collected at the bottom of the pad is segregated ba ........