Deposit Types
The copper-gold sulphide mineralization present at the Candelaria Copper Mining Complex is generally referred to as iron oxide copper gold (IOCG). Depending on lithology and the structural setting, the polymetallic sulphide mineralization can occur as veins, hydrothermal breccias, replacement mantos, and calcic skarns (Sillitoe, 2003).

The Candelaria IOCG deposit lies within the metamorphic aureole of the Lower Cretaceous magmatic arc plutonic complex that is located within the Candelaria-Punta del Cobre district, Atacama Region, northern Chile. IOCG deposits are primarily defined by their elevated magnetite and / or hematite with elevated copper and gold contents (Sillitoe, 2003). The IOCG belt located in the Coastal Cordillera of northern Chile and southern Peru is part of a volcano-plutonic arc of Jurassic to Early Cretaceous age. The arc is characterized by voluminous tholeiitic to calc-alkaline plutonic complexes of gabbro to granodiorite composition and primitive, mantle-derived parentage. Major arc-parallel fault systems developed in response to extension and transtension induced by subduction roll-back at the retreating convergent margin.

Most of the sulphide mineralization at Candelaria and Ojos del Salado occurs in breccias, stockwork veinlets, and disseminations in andesite, especially where the rocks are strongly foliated. Highergrade copper mineralization is controlled by stratigraphy in mantos and by faults, trending pre ........

Minera Ojos del Salado consists of the Santos and Alcaparrosa Underground mines. In response to a sinkhole that occurred near the Alcaparrosa mine on July 30, 2022 and a subsequent infraction notice from the Superintendencia de Medio Ambiente (SMA) alleging four environmental permit breaches and a subsequent request from SERNAGEOMIN for a temporary stoppage of the Alcaparrosa mine, mineralized material from the Alcaparrosa mine have been excluded from the LOM plan and Mineral Reserves documented in this Technical Report.

Ore from the Santos mine is hauled to the PAC processing plant located on the Minera Ojos del Salado property. Any ore above the capacity of the PAC plant is sent to the Candelaria plant for processing.

The Santos mine will continue to produce at its current rate of production of 5,100 tonnes per day of ore to 2025 then decrease to 3,700 tonnes per day of ore from 2026-2033 with an average LOM grade of 0.88% copper. The mining method employed in underground mine is sublevel open stopping.

The stopes that support the proposed LOM plan for the Candelaria and Santos underground mines can be mined as expected.

The underground mine utilize a sublevel open stoping mining method for ore extraction. This method is ideal for relatively large, vertical, thick deposits with favourable (stable) host rock.

Stope excavations can typically be up to 180 metres high with sublevels at 20 to 60 metre intervals. The length o ........

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The mines’ water supply comes from a desalination plant owned by Minera Candelaria via a pipeline that were both completed in 2013, as well as from a nearby wastewater treatment facility. The commissioning of the desalination plant has enabled the mines to cease drawing ground water from the Copiapó aquifer, the historic source of water, except in emergency situations and for potable water supply.

The main sources of water are now derived from recirculation of water from the tailings storage facilities and desalinated seawater pumped from the desalination plant located adjacent to the marine terminal at Caldera. Water from groundwater wells remains available for use in case of emergency and maintenance of the desalination plant.

Following an extensive examination of alternative water supplies, including more distant ground water wells, Minera Candelaria opted to construct a desalination plant at the Punta Padrones port site and pump the water 110 kilometres to the mine site via a dedicated pipeline and booster pump station. The desalination plant was originally designed at 300 litres per second and was later expanded to 500 litres per second.

The desalination plant itself consists of three, nominal 150-litre-per-second lines comprising pre-filtration, ultra-filtration, micro-filtration ahead of conventional reverse osmosis. The reverse osmosis plant includes 468 pressure vessels with 3,276 membranes operating at a pressure exceeding 1,000 pounds per square inch. The desalination plant was commissioned in early 2013 and reached nameplate capacity later that year. In November 2013, extraction from groundwater sources in the Copiapó aquifer was stopped, except for water for potable supply and emergencies.