The Mulatos mineral deposits are large epithermal, high-sulfidation, disseminated gold deposits. Gold mineralization is closely associated with silicic alteration within extensive areas of argillic and advanced argillic alteration. The Mulatos deposit proper is composed of the contiguous Estrella, El Salto, Mina Vieja, and Puerto del Aire Mineral Resource areas. The Escondida deposit is the faulted extension of the Mina Vieja and El Salto sub-deposits and is believed to be continuous to the northeast with the Gap, El Victor, and San Carlos mineralized areas. Although zones are often bounded by post-mineral faults, together they form a trend of 2.7 km of gold mineralization starting at the north end of the Estrella pit to the San Carlos deposit.

Within the larger Mulatos Group of Concessions, and generally within 20 km from the Mulatos deposit, geologically similar high sulfidation gold deposits, occurrences, or prospects are known.

Gold deposits of the Mulatos district are considered to be high sulphidation-state epithermal systems. Epithermal precious metal systems may be classified as high, intermediate, and low sulphidation styles. They are characterized by the sulphidation state of the hypogene sulphide mineral assemblage, and show general relations in volcano-tectonic setting, precious and base metal content, igneous rock association, proximal hypogene alteration, and sulphide abundance. Ore in all occurrences is of the type formed under epizonal co ........

The Mulatos open pit mining is a typical drill, blast, load haul operation with mining in the main pit being done with 9 meter bench heights. The open pit schedule calls for an average of 17,500 tonnes of ore per day. Open pit mining is carried out by a contractor under the direction of Mulatos staff. Waste is delivered to waste dumps south of the pit and ore is delivered to the crushing area where it is either direct dumped into the primary crusher or put on to a short term pad. The contractor currently operates with a fleet of three CAT 992 front end loaders, 14 CAT 777 haul trucks, three drills and various pieces of support equipment. El Salto, on the west side of the main pit, is the last in a series of pushbacks and is expected to be completed by the end of 2023.

Throughout the developments outlined above, the main Mulatos open pit continued to be mined. Distinct Zones mined between 2006 and 2023 within the main Mulatos pit have included the Estrella, Escondida, Mina Vieja, and El Salto deposits. The last remaining zone, El Salto, is expected to be completed in late 2023.

Mulatos Process
Ore is processed through four stages of crushing to a target crush size of 95 percent minus 3/8 inches.

Run-of-mine ore is delivered to the primary crusher feed hopper by rear-dump haul trucks. A static grizzly screen above the hopper limits the top size of rock fed to the crusher. Below the hopper, a vibrating grizzly feeder transfers ore. Grizzly screen oversize feeds the primary jaw crusher. Grizzly screen undersize joins the crusher product on the primary crusher discharge conveyor (CV-01) which feeds the primary crushed product to the second stage of crushing. A rock breaker is installed to serve the static grizzly. Tramp iron is removed from the crushed product by way of a magnet mounted above the discharge of the discharge conveyor.

Primary crushed product is fed to the secondary cone crusher. Secondary crushed product is discharged onto a conveyor (CV-02) and delivers ore to the scalping screens by conveyors (CV-03A, CV-04A). Screen oversize reports to screen oversize conveyors (CV-05A, CV-06A) which feed the radial stacker (CV-03) which discharges into the coarse ore stockpile. Screen undersize reports to conveyors (CV-07A, CV-09A) which discharges onto conveyor (CV-15) which ultimately directs ore to the fine ore stockpile.

One reclaim tunnel is installed beneath the coarse ore stockpile. Ore is withdrawn from the coarse ore stockpile by two variable speed apron feeders. The feeders discharge to a conveyor belt (CV-04) which discharges to a surge bin which is installed to choke feed the three tertiary crushers, each with a dedicated vibrating feeder.

The tertiary crushed product is discharged onto conveyor (CV-07) and fed to a vibrating screen. Screen oversize is transferred by conveyors (CV-09, CV-10, and CV-11) and is crushed in the single quaternary cone crusher. The quaternary crushed product is discharged onto the crusher conveyor (CV-12) and recirculates back to the vibrating screen. The screen undersize reports to the fine ore collection conveyor (CV13) which discharges onto the fine ore transfer conveyor (CV-14). The fine ore transfer conveyors (CV-15, CV-16, CV-17, CV-18, and CV-19) deliver ore to the fine ore stockpile. Pebble lime is added on to conveyor CV-14 from three storage silos with the rate of lime addition varying with tonnage.

One reclaim tunnel is installed beneath the fine ore stockpile. Ore is withdrawn from the fine ore reclaim stockpile by a feeder. The feeder discharges to a tunnel conveyor belt (CV-20). Cement is added on the tunnel conveyor and delivers ore to the agglomerator feed conveyors (CV-21A and CV-21B) which feed a pair of agglomerators. After agglomeration, the final agglomerated product is transferred by conveyors (CV22, CV-23, and CV-24), to a series of grasshoppers (portable conveyors), ending with a radial stacker. Ore is discharged from the radial stacker onto the heap leach pad.

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