Nexa Resources S.A. announced its 2023 Year-End Mineral Reserves and Mineral Resources relating to its operations and projects located in Peru and Brazil. As of December 31, 2023, Proven and Probable Mineral Reserves estimates amounted to 110.4 million tonnes containing 4,031kt of zinc (at higher average zinc grade) compared with 100.6 million tonnes containing 3,540kt of zinc as of December 31, 2022. The increase was mainly driven by infill and brownfield drilling at Aripuanã, partially offset by mining production depletion.

Nexa?s 2023 Year-End Mineral Reserves estimate also reflects changes in continuous refining of its geological modelling. Another addition to Mineral Reserves is the re-inclusion of the Atacocha Mineral Reserves from the underground and open pit mines, which were not included in 2022. Positive results from the Cerro Pasco Integration Project economic study carried out during 2023 support the declaration of Mineral Reserves.

The Pasco Integration Project is designed to further integrate the Atacocha and El Porvenir mines to increase production and extend mine life by eliminating the main bottlenecks in each operation, increasing mill capacity, and opening up additional exploration potential including at the integration mineralized body. The net revision of -34kt of zinc was primarily due to the increase in cut-off at Aripuanã (-140kt) balanced by stope layout and cut-off revisions at Cerro Lindo, and El Porvenir (106kt). The Proven and Probable Mineral Reserves at the Cerro Lindo Mine were estimated to total 41.15Mt at 1.49% Zn, 0.22% Pb, 0.55% Cu and 22.6 g/t Ag as of December 31, 2023, a 0.7% decrease from 41.43Mt at 1.57% Zn, 0.22% Pb, 0.59% Cu and 22.5 g/t Ag as of December 31, 2022.

The decrease was the result of mining production depletion during 2023, balanced by infill drilling in mine extensions (+23kt of zinc), and stope layout and cut-off revisions (+28kt of zinc). Mineral Reserve depletion during 2023 accounted for -5.98Mt containing 90kt of zinc. The Proven and Probable Mineral Reserves at the Vazante Mine were estimated to total 11.33Mt at 9.62% Zn, 0.21% Pb, and 13.8 g/t Ag as of December 31, 2023, down 16% from 13.50Mt at 9.64% Zn, 0.27% Pb and 15.2 g/t Ag as of December 31, 2022. The decrease was the result of mining production depletion during 2023, and geotechnical revision at Lumiadeira area (-28kt of contained zinc).

Mineral Reserve depletion during 2023 accounted for -1.70Mt containing 184kt of zinc. In 2023, Nexa added 2.11Mt of Probable Mineral Reserves with 87kt of contained zinc from the Aroeira tailings deposit after a hydrogeological and environmental study. The Proven and Probable Mineral Reserves at the El Porvenir Mine were estimated to total 14.65Mt at 4.11% Zn, 1.20% Pb, 0.23% Cu and 72.9 g/t Ag as of December 31, 2023, a 5.5% decrease from 15.50Mt at 3.60% Zn, 1.07% Pb, 0.19% Cu and 66.0 g/t Ag as of December 31, 2022. The decrease is the balance result from mining depletion, and the addition of 106kt of contained zinc from stope layout and model revision.

Mineral Reserve depletion during 2023 accounted for -2.20Mt containing 62kt of zinc. The Proven and Probable Mineral Reserves at the Atacocha (Underground) Mine were estimated to total 5.66Mt at 4.33% Zn, 1.34% Pb, 0.40% Cu, 79.8 g/t Ag, and 0.07g/t Au as of December 31, 2023. The Proven and Probable Mineral Reserves at the Atacocha (Open Pit) Mine were estimated to total 4.38Mt at 0.99% Zn, 1.15% Pb, 34.9 g/t Ag, and 0.27g/t Au as of December 31, 2023. The Proven and Probable Mineral Reserves at the Aripuanã Mine were estimated to total 31.07Mt at 4.35% Zn, 1.66% Pb, 0.15% Cu, 40.6 g/t Ag and 0.22 g/t Au as of December 31, 2023, a 3.2% increase from 30.12Mt at 3.42% Zn, 1.25% Pb, 0.17% Cu, 32.1 g/t Ag and 0.23 g/t Au as of December 31, 2022.

The Babaçu infill drilling program carried out during 2023 provided new Probable Mineral Reserves of 9.10Mt at 5.56% Zn, 2.19% Pb, 0.11% Cu, 49.6 g/t Ag, and 0.14g/t Au as of December 31, 2023, totaling an increase of 506kt of contained zinc in the reserves. We reported a loss of -140kt of contained zinc due to an increase in cut-off impacting mostly low-grade ores. Mineral Reserve depletion during 2023 accounted for -1.56Mt containing 44kt of zinc. Mineral Resources As of December 31, 2023, Nexa estimated Measured and Indicated Mineral Resources (exclusive of Mineral Reserves) were 3,259kt of contained zinc compared with 3,432kt as of December 31, 2022.

The Addition and Revision accounted for a net decrease of -173kt of contained zinc mostly due to conversion of Mineral Resources to Mineral Reserves at Aripuanã after the Babaçu infill drilling, and at the Atacocha (Underground) and Atacocha (Open Pit) Mines following the Pasco Integration Project study. At Vazante Aroeira tailings, a hydrogeologic and environmental study resulted in conversion of 108kt of contained zinc from Indicated Mineral Resources to Mineral Reserves. At the Atacocha (Underground) and Atacocha (Open Pit) Mines, the Pasco Integration Project accounted for a -175kt and -44kt reduction in contained zinc, respectively, after conversion to Mineral Reserves.

As of December 31, 2023, Nexa estimated Inferred Mineral Resources of 6,897kt of contained zinc, compared with the total of 6,626kt at the end of 2022. The addition of 543kt of contained zinc was mostly incorporated through the Babaçu drilling at Aripuanã. The net revision reduction of -271kt of contained zinc is mostly due to model revisions and reclassification at Vazante and conversion of Inferred Mineral Resources to Mineral Reserves at Babaçu.