CVRD

Oct 22, 2021

Message : MINAS GERAIS, BRAZIL 1-5 1-8 1-9 1-11 1-13 1-14 1-14 2-3 MINAS GERAIS, BRAZIL 5-1 7-6 10-2 11-1 MINAS GERAIS, BRAZIL 13-1 13-1 14-3 14-9 15-1 15-2 MINAS GERAIS, BRAZIL 16-8 20-1 20-1 20-4 24-1 MINAS GERAIS, BRAZIL 25-2 25-3 26-1 26-2 29-2 29-3 1-2 1-3 1-9 1-9 2-1 6-3 6-3 11-2 11-4 MINAS GERAIS, BRAZIL 14-1 14-2 14-3 14-5 14-8 14-9 14-11 14-18 14-20 14-22 14-26 14-27 14-28 14-29 14-31 14-36 14-36 15-1 15-2 15-3 16-8 17-1 18-2 18-3 21-1 21-2 21-2 21-3 21-3 4-3 MINAS GERAIS, BRAZIL 7-10 10-2 11-5 11-6 11-7 11-8 11-10 11-12 11-12 11-13 11-13 11-15 11-16 Figure 11-14: 11-16 13-3 14-4 14-5 14-7 Figure 14-5: Long-Term vs. Short-Term Distribution for Each Domain in the Short-Term Area (Long-Term in Red Dots; Short-Term in Block Dots) 14-10 Figure 14-6: Long-Term vs. Short-Term Swath Plot for Each Domain in the Short-Term Area (Long-Term are in Red Lines and Short-Term in Black Lines) 14-11 14-19 14-25 14-26 14-28 14-30 14-34 14-35 14-35 16-5 17-5 MINAS GERAIS, BRAZIL ARD CN DD ESMS FA/AAS)AA HW LO TOC viii MINAS GERAIS, BRAZIL MRDM PAEM PCA PEA TSF TOC ix MINAS GERAIS, BRAZIL MINAS GERAIS, BRAZIL Executive Summary This National Instrument (NI) 43-101 Technical Report (Technical Report) on the Riacho dos Machados Gold Mine (RDM or Mine), Minas Gerais, Brazil was prepared by Equinox Gold Corp. (Equinox) under the guidance and supervision of the Qualified Persons (QP). This Technical Report provides an update on the Mineral Resources and Mineral Reserves with an effective date of December 31, 2020 and conforms to NI 43-101 Standards of Disclosure for Mineral Projects. The Mine is operated by Mineração Riacho dos Machados (MRDM), a wholly owned Brazilian-domiciled subsidiary of Equinox. Equinox is a publicly listed Canadian mining company with significant gold producing, development, and exploration stage properties in Canada, USA, Brazil, and Mexico. Gold production by Equinox totalled approximately 477 koz in 2020. The Mine is a conventional open pit and carbon-in-leach (CIL) operation, which is scheduled to process up to 7,890 t/d (2.88 Mt/a) with the potential to expand to 9,000 t/d (3.28 Mt/a). Current production will recover 484 koz Au over a mine life of seven years, consisting of six years of mining and two additional months of processing. Potential underground production could extend the mine life. Equinox has all required environmental licences and permits to conduct work on the property. Table 1-1 summarizes the updated Mineral Resource estimate exclusive of Mineral Reserves as of December 31, 2020. Table 1-2 summarizes the updated Mineral Reserve estimates as of December 31, 2020. The Mineral Resource and Mineral Reserve estimates conform to Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Definition Standards for Mineral Resources & Mineral Reserves dated May 10, 2014 (CIM Definition Standards [2014]). PAGE 1-1 2. Mineral Resources are exclusive of Mineral Reserves. 3. Open pit Mineral Resources are reported at a cut-off grade of 0.30 g/t Au. 4. Underground Mineral Resources are reported at a cut-off grade of 1.36 g/t Au 5. Mineral Resources are estimated using a gold price of US$1,500/oz and constrained by conceptual pit shell and stope shells. 6. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. 7.The Mineral Resources statement has been prepared by Felipe Machado de Araújo, MAusIMM (CP), a full-time Equinox employee, who is Qualified Person as defined by NI 43-101. 8. Totals may not add due to rounding. PAGE 1-2 Property Description and Location The Mine is in the northern part of Minas Gerais State, Brazil. The mine site is 145 km by road northeast of the city of Montes Claros (population 413,000) and 25 km from the nearest town, Riacho dos Machados (population 10,000). The center of the current open pit has geographic coordinates of 16°03'40" south latitude and 43°08'16" west longitude and an approximate elevation of 895 masl. 1.2.2 Land Tenure The property consists of eight exploration permits and two mining concessions with a total area of 14,979.98 ha. For the exploration permits, a final report detailing the tenure for the Mine is held under the name of MRDM, an indirect wholly owned subsidiary of Equinox, incorporated under the laws of Brazil and registered with the Federal Taxpayer's Roll under No. 08.832.667/001-62. The property was initially staked under the name of Ouro Fino Gold Mine on March 30, 2001 (File #16,835), and was subsequently registered under the name of MRDM. PAGE 1-3 History Companhia Vale do Rio Doce (CVRD), now Vale, discovered the MRDM deposit in early 1986. CVRD operated the property as an open pit gold mine and heap leach operation until closure in 1997. The Mine remained idle from 1997 until October 2008, when Carpathian Gold Inc. (Carpathian) acquired the mineral rights and started prospecting and exploration. Carpathian restarted the Mine in March 2014. Brio Gold Inc. (Brio) acquired the Mine from Carpathian on April 29, 2016. Leagold acquired the Mine through the acquisition of Brio on May 24, 2018. On March 10, 2020, Equinox and Leagold completed an at-market merger. As a result, the operating entity MRDM is now a wholly-owned subsidiary of Equinox. 1.2.4 Geology and Mineralization The Mine occurs in the north-south-trending Araçuaí fold and thrust belt along the eastern margin of the São Francisco Craton, a major Archean-age basement block that underlies more than 1,000,000 km2 in eastern Brazil. The Araçuaí Fold Belt is 15 to 45 km wide and consists of a series of late Archean to late Proterozoic metavolcanic and metasedimentary rocks that were deposited in a broad intracontinental-to-oceanic rift-type basin that existed between the São Francisco Craton and the Congo Craton (now part of Africa). Subsequent closure of this rift basin by prolonged continental collision strongly deformed the rock strata, and the units were metamorphosed, folded, intruded, and thrust westward against the São Francisco Craton during the late-Proterozoic Brasiliano orogeny. Mineralization along the Araçuaí Fold Belt is thought to be the result of hydrothermal fluids generated by syntectonic igneous and metamorphic activity. Immediately east of the Araçuaí Fold Belt is a north-south-trending, 300 km long structural window cored by Archean-aged migmatites and flanked by apparent décollement (basal detachment) structures and Proterozoic supracrustal sequences (Espinhaço and São Francisco Supergroups) forming a regional antiformal structure. This structural window has been termed the Guanambi-Corretina Block by Barbosa (1996) or the Porteirinha Complex by DOCEGEO (1994). At the Mine, basement gneissic-granitic rocks are interpreted to be overthrust westward onto the supracrustal rocks of the Riacho dos Machados Group (RMG) as part of the Brasiliano-Pan-African event. The tectonic superposition of basement rocks over supracrustal sequences is described along the entire eastern border of the São Francisco Craton with mineral occurrences known along this lineament. The principal host for the gold mineralization is the quartz-muscovite schist unit of the RMG, a hydrothermal alteration product formed along a district-scale shear zone. This shear zone extends almost 30 km in a N20°E strike direction, dipping 40° to 45° east. In the mineralized zone, the regional amphibolite facies mineral assemblage is progressively altered to assemblages typical of greenschist facies. In detail, the gold mineralization occurs as "stacked" tabular horizons that are generally concordant with the overall shear zone and associated foliation. Stacked footwall and hanging wall zones are typically separated by 3 to 10 m of unmineralized rock. Continuity of the overall zone along strike and at depth is good, with gold mineralization occurring continuously over a 2,000 m strike length and up to 1,000 m down dip. Gold grades in the mineralized zone are closely related to sulphide content, especially arsenopyrite. Gold occurs as microscopic grains of native gold that are typically finer than 400 mesh (37 µm) in size. The gold grains occur interstitial to quartz, muscovite, and sulphide grains, and also as inclusions in arsenopyrite, and less commonly in pyrrhotite, quartz veinlets, tourmaline, and pyrite. PAGE 1-4 Exploration Status The Mine remains the principal gold deposit in the district. Open-pit expansion potential exists along trend to the north and south and underground potential exists down dip where mineralization has been intersected by widely spaced drill holes. In addition, the Mine is located on a 30 km trend of alteration and mineralization in the RMG that has not been comprehensively drill tested. Drilling in the Mine area has been conducted in phases by several companies since 1987. Brio completed the latest diamond drilling at the Mine in 2017. Additional reverse circulation drilling was completed in short-term drilling programs from 2018 to 2020. 1.2.6 Mineral Processing and Metallurgical Testing The RDM process plant feed comprises 40% North Pit, 30% Central Pit, 30% South Pit, representing zones in the pit with different characteristics. Since 2014, the main operational restrictions of the RDM plant were the lack of available water and power supply; however, these issues have since been solved. Production throughput was limited by a lack of process water several times between 2016 and 2020. To address this limitation, a 4 Mm3 Water Storage Facility (WSF) was constructed in early 2018. The catchment area of the dam was significantly affected by farming activities, which caused a slow fill rate. Low water levels again caused a brief production shortfall in late September to mid-October 2019; however, the 2020 rainy season has significantly increased the volume of water stored in the WSF and the plant has been able to maintain year-round operations since then. Following completion in March, 2019 of a 138 kV power line that connects to the Brazilian national power grid operated by Companhia Energética de Minas Gerais (CEMIG), the Mine now operates with electrical power from CEMIG's distribution lines instead of the previously-used diesel generators. This change allowed plant throughput to be increased from 290 t/h to 342 t/h by enabling operation at a higher steel-ball load in the mill. A series of process improvements were implemented in 2019 and 2020. The measured improvement in metallurgical recovery is approximately 9%, achieving 87% recovery with a lower standard deviation. These improvements included: • • CVRD conducted cyanide leach tests at various grind sizes on 6 bulk samples. Column leach tests showed average gold recovery of 67% at -2 mm crush size. Bottle roll tests showed average gold recovery of 81% at 74 µm grind size and increasing recovery with a finer grind. They observed that sulphide ores responded reasonably well to cyanide leaching. • SGS-Geosol Brazil (SGS) conducted cyanide leaching kinetic tests and CIL tests on composite samples from Areas III, IV, and V of the open pit with a particle size of 80% passing 75 µm. Gold extraction ranged from 88.6% to 91.9% after 72 hours of leaching in the presence of activated carbon. • G & T Metallurgical Services, Ltd. (G&T) conducted tests on 11 samples that represented oxide, transition, and sulphide ore. Three series of leaching tests were conducted that included grinding, leaching, cyanide destruction, and sedimentation. The three test series used were standard cyanide leach conditions, leaching tests with lead nitrate added, and both lead nitrate and activated carbon added. The average gold extraction was 91% after 72 hours of leaching at a particle size fraction of P80 = 55-60 µm. • RDM´s process team carried out a series of testworks with good results in 2019 and the plant process improvements were implemented in 2019 and in 2020. 1.2.7 Mineral Resources The Mineral Resources, which are summarized in Table 1-1 and are exclusive of the Mineral Reserves, were estimated from a block model constructed by Equinox and have an effective date of December 31, 2020. Results from grade control drilling conducted during 2019 and 2020 were used to update this model. This Mineral Resource estimate conforms to CIM Definition Standards. 1.2.8 Mineral Reserves The Mineral Reserves, which are summarized in Table 1-2, were prepared by Equinox with an effective date of December 31, 2020. Mineral Reserves are reported using a gold price of US$1,350/oz Au with a mine design based on the selected pit shell and an overall metal recovery of 87%. The authors are of the opinion that the Measured and Indicated Mineral Resources within the final mine design can be classified as Proven and Probable Mineral Reserves, and are not aware of any mining, metallurgical, infrastructure, permitting, or other relevant factors that could materially affect the Mineral Reserve estimate. 1.2.9 Mining Method Conventional open pit mining methods are employed at the Mine, including drilling, blasting, loading, and hauling using a fleet consisting of Atlas Copco flexiROC D65 (140 mm/5.5 in. diameter) diesel drill rigs; Caterpillar 390, Hitachi 2500 and 1200 hydraulic excavators; and Caterpillar 775, Caterpillar 777, and Komatsu 685 mechanical rear-dump trucks. Current pit bottom elevations for the north and south ends of the open pit are approximately 717 and 705 m, respectively, and the crusher elevation is 865 masl. Surface rights are sufficient for mine waste stockpiles, tailings facility, and processing plants sites. PAGE 1-6 MINAS GERAIS, BRAZIL The strip ratio of the design pit is relatively high, at approximately 6.9:1 (waste:ore). The mined tonnage is proposed to be at a constant rate throughout the life-of-mine (LOM). Haul distances to the waste dumps and run-of-mine (ROM) ore stockpile crusher area are moderate (approximately 1.8 to 2.6 km). Total daily waste material movement is estimated to be approximately 60,000 t/d, and direct ore haulage is estimated to be 7,890 t/d (2.88 Mt/a). Alternate waste dump locations, although limited, are under evaluation. The mining permit would require an amendment to modify waste dump designs. Weather and elevation should not impact productivities; however, severe rainfall may occur in the region. In addition to recycled process water, the Mine relies on make-up water from a water storage dam and a well field. 1.2.10 Recovery Methods The circuit was designed to process an average of 7,890 t/d (2.88 Mt/a), but, with some modifications, could be expanded to 9,000 t/d (3.28 Mt/a). The overall process flowsheet consists of: • Environmental, Permitting, and Social Considerations The Mine is in a remote and dry location, and vegetation and faunal compositions are critical habitat for many biodiversity resources. The general area of the Mine was previously disturbed by CVRD, which operated the Mine from 1989 to 1997. The mining operations will result in vegetation suppression over an area of approximately 362 ha. Due to the previous mining activities and environmental liabilities, MRDM conducted supplementary baseline studies to assess groundwater, surface water, and soil quality prior to the start of operations. As part of conditions of the environmental license, MRDM conducts environmental monitoring programs of surface water, groundwater, soil, fauna, and flora to closely monitor potential changes in the quality of these resources. MRDM has ongoing reclamation programs and has set-aside areas for biodiversity conservation. The Mine currently operates under the permits and licenses listed in Table 1-3. All licences and permits are in good standing as of the date of this report. Table 1-3: MRDM Permitting Status Licences and Permits Introduction This National Instrument (NI) 43-101 Technical Report on the Riacho dos Machados Gold Mine, Minas Gerais, Brazil was prepared by Equinox Gold Corp. Equinox under the guidance and supervision of the Qualified Persons. This Technical Report provides an update on the Mineral Resources and Mineral Reserves with an effective date of December 31, 2020 and conforms to NI 43-101 Standards of Disclosure for Mineral Projects. On May 24, 2018, Leagold acquired Brio Gold Inc. (Brio), which included ownership of three operating gold mines in Brazil: tha Riacho dos Machados, Fazenda Brasileiro, and Pilar mines, as well as the Santa Luz Project. On March 10, 2020, Equinox acquired all of the issued and outstanding common shares of Leagold resulting in Leagold being a wholly-owned subsidiary of Equinox. Mineração Riacho dos Machados (MRDM), now a wholly owned Brazilian-domiciled subsidiary of Equinox, operates the Mine. Equinox is a publicly listed Canadian mining company with significant gold producing, development, and exploration-stage properties in Canada, the USA, Brazil, and Mexico. Gold production by Equinox totalled approximately 477 koz Au in 2020. The Mine is a conventional open pit and carbon-in-leach (CIL) operation, which is scheduled to process up to 7,890 t/d (2.88 Mt/a) with the potential to expand to 9,000 t/d (3.28 Mt/a). Current production will recover 484 koz Au over a mine life of seven years, consisting of six years of mining and one additional year of processing. Potential underground production could extend the mine life. Equinox has all required environmental licences and permits to conduct work on the property. 2.1 Sources of Information Table 2-1 provides a list of QPs and the Technical Report sections for which they are responsible. The QPs' certificates are included in Section 29. Table 2-1: Qualified Persons and Report Section Responsibilities Section • Assumptions, conditions, and qualifications as set forth in this Technical Report. The QPs have not performed an independent verification of the land title and tenure information, as summarized in Section 4, nor have they verified the legality of any underlying agreement(s) that may exist concerning the permits or other agreement(s) between third parties, as summarized in Section 4. For this topic, the QPs have relied on information provided by Equinox's legal department. The QPs have not performed an independent verification of the permitting and environmental monitoring information, and have relied on documents and information provided by Equinox's Health, Safety, Environment, and Community (HSEC) teams. The QPs have relied on various Equinox departments for guidance on applicable taxes, royalties, and other government levies or interests applicable to revenue or income from the RDM mine.The Authors used their experience to determine if previous information and/or reports were suitable and appropriate for inclusion in this technical report. Equinox did not seek independent review of these items. PAGE 3-1 Land Tenure The property consists of eight exploration permits and two mining concessions with a total area of 14,979.98 ha, as shown in Figure 4-2. For the exploration permits, a final report detailing the tenure for the Mine is held under the name of MRDM, an indirect wholly owned subsidiary of Equinox, incorporated under the laws of Brazil and registered with the Federal Taxpayer's Roll under No. 08.832.667/001-62. The property was initially staked under the name of Ouro Fino Gold Mine (File #16,835) on March 30, 2001, and was subsequently registered under the name of MRDM. Surface rights for the Mine were purchased by MRDM and owned by individuals and entities in Minas Gerais. Equinox believes that there are no reservations, restrictions, rights-of-way, or easements on the Mine to any third party. Through the Agência Nacional de Mineração (National Mining Agency or ANM), the Brazilian government is authorized to grant the rights for a mining concession to any entity that discovers a new mineable deposit. There are no expiration dates on the mining concession held by MRDM, provided the company meets expenditure and environmental requirements and pays a required annual mining fee. The 2 Final Exploration Reports that were approved have more one year to submit an economic study (September 30, 2022). However, this deadline could be postopone for more one year. The expenditure and environmental requirements have been met, and MRDM is current with all requirements to hold the mining tenements in good standing. Table 4-1 provides a summary of the mining property concession and exploration permits. Table 4-1: Mining Property Tenements Property Royalties Certain royalties are levied on mineral production in Brazil under Federal law. The current statutory royalty imposed by the Federal government on gold properties is 1.5% of sales proceeds less sales tax, transportation, and insurance costs. Additionally, a royalty must be paid to the landowner if the surface rights do not belong to the mining titleholder. This landowner royalty is equal to one-half the government royalty and would amount to an additional 0.5% in the case of gold. MRDM owns the surface rights that cover the deposit area and infrastructure so no additional landowner royalties exsit. The Mine also carries a 1% royalty on the gold and a 2% royalty on base metals, payable by MRDM to Nomad Royalty Company, which acquired the royalty interest from Serra da Borda Mineração e Metalurgia SA, the previous beneficiary. Initially, there was a royalty agreement between Mineração Brilhante and MRDM. On October 30, 2017, MRDM received a notification informing it that the royalty rights of Mineração Brilhante, which had previously been assigned to Irajá Mineração Ltda., would now be assigned to Serra da Borda Mineração e Metalurgia S/A. Serra da Borda Mineração e Metalurgia S/A is a subsidiary of Yamana Gold Inc. (Yamana). Finally, in May 2020, Yamana reports the assignment of the mining rights of Serra da Borda Mineração e Metalurgia S/A to Nomad Royalty Company. The mineralization in the Mine area currently carries no economic base metals. PAGE 4-4 5.1 Accessibility The RDM Mine is approximately 145 km by road northeast of Montes Claros in the northern part of Minas Gerais State, southeastern Brazil. The Mine can be accessed from Montes Claros by travelling west on Highway 251 and north on MG-120. The main gate is accessed from a westbound gravel road off MG-120. The nearest towns are Riacho dos Machados (population 10,000), approximately 23 km northeast from the Mine and Porteirinha (population 39,000), approximately 55 km northeast from the Mine. Montes Claros (population 400,000) is the region's largest industrial city, offering full-service facilities and daily commercial air flights to the major Brazilian cities of Belo Horizonte (560 km from the Mine), Brasília, and Salvador. 5.2 Climate The Mine is in southeastern Brazil in the northern part of Minas Gerais, in the Serrado climate zone. The climate is semi-tropical with two seasons - a dry winter and a rainy summer - with the main period of rain occurring from November to March. Average temperatures vary from 17°C in January to 30°C in July. Annual precipitation ranges from approximately 300 to 1,700 mm, with an average of 800 mm over the last few years, and pan evaporation averages 1,537 mm/a. Severe rainfall and drought can occur in the Mine area. In December 2013, the site experienced a total monthly precipitation amount of 556 mm, during which the water overtopped the liner that was being installed in the tailings storage facility (TSF) at the time and ran underneath the liner. The Mine has experienced several droughts, which affected the water supply during those times. Construction of the water storage facility to mitigate drought effects was completed in April 2017. 5.3 Local Resources The Mine area has a moderate history of mining activity. Mining suppliers and contractors are locally available. Both experienced and general labour are readily available from the nearby towns of Porteirinha and Riacho dos Machados (population 39,000 and 10,000, resp.). Within the state of Minas Gerais, many mining-related services are available including drilling and mining contractors, and geological and engineering consulting firms. PAGE 5-1 • Water dam and pipeline. Electricity used to be produced by eleven diesel-powered generators. In the second half of 2019, the Mine started operating with transmitted energy supplied by the Minas Gerais State Energy Distribution Company (CEMIG), which built a 138 kV transmission line that connects the Janaúba 4 Substation to the new Mine substation. Both substations were constructed as part of the transmission-line project. The transmission line is approximately 35 km long, within a 25 m-wide right-of-way (ROW). CEMIG had negotiated the easements along the ROW and was responsible for the environmental licence and the substations' operations, together with the 138 kV transmission line. 5.5 Physiography The Mine is located within the Serra do Espinhaço (Espinhaço Mountains), which divides the São Francisco and Jequitinhonha river basins. The terrain consists of rolling hills that are locally steep and drained by sparse intermittent streams mainly active in the wet season. Elevations range from 770 to 900 masl. The dominant vegetation is overgrown, semi-tropical savanna known as "cerrado," consisting of brushy forest land interspersed with open grassy fields. The local area supports only limited agriculture, mainly subsistence cattle grazing near the mine site. In addition to ranching, there are eucalyptus tree farms producing charcoal for metallurgical ovens. PAGE 5-2 Ownership History Companhia Vale do Rio Doce (CVRD), now Vale, discovered the RDM deposit in early 1986. CVRD operated the property as an open-pit gold mine and heap leach operation until closure in 1997. The Mine remained idle from 1997 until October 2008, when Carpathian Gold Inc. (Carpathian) acquired the mineral rights and started prospecting and exploration. Carpathian restarted the Mine in March 2014, and Brio acquired the Mine from Carpathian on April 29, 2016. Through the acquisition of Brio, Leagold acquired the Mine on May 24, 2018. On March 10, 2020, Equinox and Leagold completed an at-market merger of equals. As a result, the operating entity MRDM is now a wholly-owned subsidiary of Equinox. 6.2 Exploration and Development History CVRD, through its exploration arm DOCEGEO, conducted geological mapping, geochemical and geophysical surveys, and trenching from 1979 to 1987. The work resulted in the discovery of the Ouro Fino deposit. From 1987 through 1994, CVRD conducted the following exploration: • Reverse circulation (RC) drilling to define the oxide gold mineralization - Most of the RC drill holes were less than 50 m deep to a maximum of 80 m. No details on sample quality are available, for example, whether they were wet or dry. • Diamond drilling (DD) to explore the deeper sulphide mineralization - DD holes with an "F" prefix (surface DD) were collared with HQ-size core (76 mm diameter) in the saprolite and weathered rock, then reduced to NQ-size core (54 mm diameter) after the hole intercepted fresh rock. The shorter holes in this series ranged from 30 to 80 m deep, with longer holes from 300 to 416 m. The "FD" series core holes were drilled in the same manner as the "F" holes, except the core was reduced to BQ-size (36 mm diameter) below a depth of 540 m. The shorter holes in this series ranged from 95 to 150 m deep and the deeper holes from 700 to 900 m. The "SU" series core holes were drilled from the underground workings with AQ-size core (33 mm diameter). These holes ranged from 10 to 90 m. • Underground exploration to define the mineralization below the southern portion of the open pit - the work included a vertical shaft, lateral development, underground drilling to explore further the deeper sulphide mineralization, and metallurgical testwork (Tecnomin, 2011). 6.3 Historical Resource Estimates Prior to the start of mining operations in 1989, CVRD estimated open-pit oxide Mineral Reserves of 2.7 Mt grading 2.22 g/t Au, containing 193 koz Au. This estimate is historical in nature but it is relevant because it shows a good reconciliation with the actual production. PAGE 6-1 MINAS GERAIS, BRAZIL In 1996, CVRD estimated underground sulphide Mineral Resources of 2.59 Mt grading 4.88 g/t Au, containing 405 koz Au in the Measured and Indicated categories, and 1.19 Mt grading 4.01 g/t Au, containing 153 koz Au in the Inferred Resource category. The historical estimate should not be relied upon, and Equinox is not treating it as current Mineral Resources. Cube Consulting Pty Ltd (Cube) prepared Mineral Resource estimates for Carpathian in December 2014, with 28.9 Mt grading 1.1 g/t Au, containing 1,002 koz Au in the Measured and Indicated categories, and 8.1 Mt grading 1.4 g/t Au, containing 404 koz Au in the Inferred category. The Cube Proven and Probable Mineral Reserves were estimated to be 18.87 Mt grading 1.17 g/t Au, containing approximately 711 koz Au, which combined the open pit and the stockpiles (Cube, 2014a). Roscoe Postle Associates Inc. (RPA) prepared Mineral Resource and Mineral Reserve estimates for Leagold with an effective date of September 30, 2015 (RPA, 2015), which RPA (2018) updated to an effective date of May 31, 2018 in a report readdressed to Equinox. Measured and Indicated Mineral Resources, inclusive of Mineral Reserves, were estimated to total 39.3 Mt at an average grade of 1.00 g/t Au, which equated to 1,259 koz of contained gold. An additional Inferred Mineral Resource was estimated to be approximately 8.3 Mt at an average grade of 1.50 g/t Au, which equated to 401 koz of contained gold. The current Mineral Resource and Mineral Reserve estimate discussed in Sections 14 and 15, respectively, supersedes the May 31, 2018 Mineral Resource and Mineral Reserve estimates. 6.4 Past Production CVRD began the open pit operation at the Ouro Fino deposit in 1989. Oxidized gold ore was mined and processed by cyanide heap leaching until 1997 when operations ceased. Production from the operation is summarized in Table 6-1. Table 6-1: Historical Production Summary - CVRD Year Geological Setting and Mineralization The description of the geological setting and mineralization and references therein are mainly taken from Tecnomin (2011). 7.1 Regional Geology The Mine occurs in the north-south-trending Araçuaí fold-thrust belt along the eastern margin of the São Francisco Craton, a major Archean-age basement block that underlies more than 1 Mkm2 in eastern Brazil. The Araçuaí Fold Belt is 15 to 45 km wide and consists of a series of late Archean to late Proterozoic metavolcanic and metasedimentary rocks that were deposited in a broad intracontinental-to-oceanic rift-type basin that existed between the São Francisco Craton and the Congo Craton (now part of Africa). Subsequent closure of this rift basin by prolonged continental collision strongly deformed the rock strata, and the units were metamorphosed, folded, intruded, and thrust westward against the São Francisco Craton during the late-Proterozoic Brasiliano orogeny. Mineralization along the Araçuaí Fold Belt is thought to be the result of hydrothermal fluids generated by syntectonic igneous and metamorphic activity. Immediately east of the Araçuaí Fold Belt occurs a north-south-trending, 300 km long structural window cored by Archean-aged migmatites (Porteirinha Complex) and flanked by apparent décollement (basal detachment) structures and Proterozoic supracrustal sequences (Espinhaço and São Francisco Supergroups) forming a regional antiformal structure. This structural window has been termed the Guanambi-Corretina Block by Barbosa (1996), or the Porteirinha Complex by DOCEGEO (1994). At the Mine, basement gneissic-granitic rocks are interpreted to be overthrust westward onto the supracrustal rocks of the Riacho dos Machados Group (RMG) as part of the Brasiliano-Pan-African event. The tectonic superposition of basement rocks over supracrustal sequences is described along the entire eastern border of the São Francisco Craton, with mineral occurrences known along this lineament. 7.1.1 Regional Lithology The major Precambrian rock sequences included in the Araçuaí Fold Belt, from oldest to youngest, are as follows: Porteirinha Complex (Córrego do Cedro Metamorphic Complex) The Porteirinha Complex is an Archean age granite-gneiss and migmatite basement complex, which includes minor mafic metavolcanics intercalations and has tight north-south folding; part of a poorly understood tectonic block immediately east of the São Francisco Craton. Riacho dos Machados Group The RMG is a Late Archean to Early Proterozoic age, strongly metamorphosed, volcanic-sedimentary rock sequence comprising mafic to ultramafic rocks with mica schist and quartz-feldspar schist. This sequence contains a local rock sequence, the Ouro Fino Sequence, which is the principal host for gold deposits at the Mine. The RMG is highly sheared and exhibits sheared contacts. PAGE 7-1 MINAS GERAIS, BRAZIL The protoliths for the RMG are interpreted predominantly as metasedimentary (metapelite), metavolcanic, and undifferentiated metavolcano-sedimentary units. The metasedimentary unit is dominated by pelitic schists (quartz-biotite), with variable portions of plagioclase, garnet, staurolite, and kyanite. Quartzofeldspathic schists occur in subordinate proportions and are composed essentially of plagioclase, quartz, phlogopite, and microcline; according to Fonseca (1993), this lithology type corresponds to a metamorphosed volcaniclastic rock. The undifferentiated metavolcano-sedimentary unit consists of intercalated metasedimentary and metavolcanic rocks in the form of titanite-bearing amphibolites and chlorite-talc-tremolite-garnet-biotite-chlorite and carbonate-serpentine-chlorite-tremolite schists. Fine-grained amphibolites and mafic/ultramafic schists are also intercalated with the metapelites, and shearing has produced schistose rocks predominantly composed of chlorite and muscovite. Paciência Intrusive Suite This suite consists of early to Mesoproterozoic-age bodies of granite, quartz monzonite, quartz diorite, diorite, and gabbro that intrude the Riacho dos Machados sequence. Intrusive activity was syntectonic to late tectonic. Espinhaço Supergroup This comprises a thick supracrustal sequence of Mesoproterozoic age, moderately metamorphosed sedimentary-volcanic rocks, mainly sericitic quartzite, phyllite, conglomerate, and schistose felsic volcaniclastic rocks. Salinas, Macaúbas, and Bambuí Groups These groups comprise sequences of Neoproterozoic age, weakly metamorphosed sedimentary rocks, including slates, meta-siltstones, phyllites, meta-arenites, quartzite (locally iron rich), and greenstone. 7.1.2 Regional Structural Geology The supracrustal late-Archean to early-Proterozoic rocks of the RMG are hosted within the Córrego do Cedro Archean gneissic-dome complex. The RMG rocks are found in north-south elongated belts up to 6 km long within the gneissic basement, the belts being generally parallel to strike of the Araçuaí Fold Belt. The mica schists of the RMG host the gold mineralization, exhibit well-developed planar foliation, and thrust fault-related mylonitic shear fabrics that strike N20°E and dip 35° to 45° to the southeast. Generally, lithological contacts are parallel to thrust faults that juxtapose schists, gneisses, and granitic rocks. The shear zones and thrust faults are silicified, sericitized, and sulphidized. Gold mineralization occurs as distinct tabular zones concordant with metamorphic and shear foliation. The mineralized zone at the mine site has a known continuous strike extent of 2,000 m. Geologic mapping and a linear arsenic-in-soil anomaly indicate that mineralization extends northward from the Mine for a further 10 km along strike. Three major thermal-tectonic events are recognized in the area: Archean, Mesoproterozoic (Transamazonic), and Neoproterozoic (Brasiliano). The oldest event is related to migmatization of the gneissic basement rocks (Porteirinha Complex), and the second event possibly resulted in the structural deformation of the RMG. The third event resulted in thin-skinned décollement tectonics and the development of the west-verging Araçuaí fold-thrust belt. The regional geology is illustrated in Figure 7-1. PAGE 7-2 7.3.1 Biotite (Quartz-Oligoclase-Sericite) Schist with Staurolite and Garnet This is a medium- to coarse-banded unit consisting of chloritized biotite (25% to 30% including 5% to 15% muscovite), moderately to strongly sericitized oligoclase (15% to 30%), and quartz (35% to 40%). Staurolite and garnet occur in separate bands. The staurolite clasts (up to one centimetre or more in size) are moderately to strongly sericitized and occasionally chloritized. Other accessory minerals include tourmaline, rutile, apatite, ilmenite, and epidote, with rare zircon and carbonate crystals. Petrographic studies suggest the protolith (original rock) for this unit was a pelitic sedimentary rock. 7.3.2 Quartz-Feldspar Schist This unit has a more restricted occurrence than the other units in the central-north portion of the area. It consists of quartz, sericitized, and kaolinized oligoclase (40% to 47%), phlogopite mica (2% to 8%), microcline (3% to 5%), and muscovite (altered from phlogopite). The schist is grey (white when weathered) and has sparse fine-grained porphyroclastic texture within a moderately to well-developed mylonitic foliation. The protolith is considered to have been a felsic volcaniclastic rock. 7.3.3 Quartz-Muscovite Schist This unit is the principal host for the gold mineralization at the Mine. The rock is white to clear greenish (yellowish-white when weathered) and consists predominantly of quartz and muscovite. Chlorite is also present in variable amounts, with small amounts of siderite or calcite, and up to 5% sulphide minerals occurring as pyrrhotite, pyrite, arsenopyrite, and rare chalcopyrite and sphalerite. Quartz-muscovite schist is potassically altered biotite schist or quartz-feldspar schist that formed in hydrothermally altered shear zones. 7.3.4 Quartz-Sericite/Muscovite-Biotite/Chlorite Schist This is likely a transitional lithologic unit formed from the partial hydrothermal alteration of the biotite schist and quartz-feldspar schist units. Contacts with the other units are gradational. The distribution of the above lithologies and their subtypes is illustrated in Figure 7-3. Figure 7-4 shows a geological cross-section of the Mine. PAGE 7-6 7.3.5 Mineralization The principal host for the gold mineralization is the quartz-muscovite schist of the RMG, a hydrothermal alteration product formed along a district-scale shear zone. This shear zone extends almost 30 km in a N20°E strike direction, dipping 40° to 45° east. In the mineralized zone, the regional amphibolite facies mineral assemblage is progressively altered to assemblages typical of greenschist facies (da Fonseca et al., 1997). In detail, the gold mineralization occurs as "stacked" tabular horizons that are generally concordant with the overall shear zone and associated foliation. Stacked footwall and hanging wall zones are typically separated by 3 to 10 m of unmineralized rock. Continuity of the overall zone along strike and at depth is good, with gold mineralization occurring continuously over a 2,000 m strike length and up to 1,000 m down dip. Gold grades in the mineralized zone are closely related to sulphide content, especially arsenopyrite. Gold occurs as microscopic native-gold grains typically finer than 400 mesh (37 µm). The gold grains occur interstitial to quartz grains, muscovite grains, and sulphide grains, and also as inclusions in arsenopyrite, and less commonly in pyrrhotite, quartz-veinlets, tourmaline, and pyrite. PAGE 7-8 Tourmaline veins (fine-grained massive intergrown). The arsenic content of the mineralization is relatively high, with an average of approximately 4,000 ppm for samples greater than 1.0 g/t Au. Silver content is very low, with the average Ag/Au ratio of 0.5:1.0 for samples with a gold concentration of greater than 1.0 g/t. Antimony, copper, lead, and zinc are not commonly anomalous. The gold mineralization is closely related to the structural fabric. The mineralizing fluid was probably channelled upward in the thrust-related shear zones with minor or local lateral escape into intersecting shear zones. Brittle deformation at the RDM deposit is limited to poorly defined cross-faults that may have anomalous geochemistry but do not host gold mineralization. Spatially, geology and mineralization can be divided into three distinct areas in cluding the ore, marginal and distal zones as shown in Figure 7-5. The area presents the occurrence of graphite, which influences the metallurgical behaviour of the ore. Graphite occurs in shear zones filling intrafolial planes, ranging from 2 to 20 cm thick, and in the form of boulders, with lenticular geometry or symmetrical boudins associated with quartz veins, with thicknesses of up to 1.5 m. They have dark grey and black coloration and low hardness, and due to graphite's lubricating characteristics, act as zones of geomechanical weakness. Graphite is in non-mineralized areas, associated with domains of marginal or waste contents, or in mineralized areas with the presence of high sulphidation. PAGE 7-9 Deposit Types The RDM deposit is considered a classic mesothermal orogenic gold deposit in a sheared and deformed Archean- to Proterozoic-age greenstone belt sequence comprising metamorphosed volcanico-sedimentary rock units intruded by slightly younger syn-tectonic or post-tectonic igneous bodies. The deposit summary provided below is based on overview descriptions by Dubé and Gosselin (2007), Goldfarb et al. (2005), Goldfarb et al. (2001), and Groves et al. (1998). Orogenic gold systems form some of the largest gold deposits and districts in the world (e.g. Kalgoorlie in Australia, Timmins in Canada, and Ashanti in Ghana). Their name reflects a temporal and spatial association with late stages of orogenesis. Formation of most orogenic gold mineralization was concentrated during the Neoarchean (2.8 to 2.55 Ga), Paleoproterozoic (2.1 to 1.8 Ga), and Phanerozoic (600 to 50 Ma); these periods coincide with major orogenic events. An important subtype of orogenic gold deposits is those that are dominantly hosted by mafic metamorphic rocks in granite-greenstone terranes, referred to here as greenstone-hosted orogenic gold. Greenstone-hosted orogenic gold deposits are structurally controlled epigenetic deposits. Gold occurs in networks of laminated quartz-carbonate fault-fill veins hosted in moderately to steeply dipping, brittle-ductile shear zones and faults, with locally associated extensional veins and hydrothermal breccias. Most of these deposits are hosted by meta-mafic rocks of greenschist to locally lower amphibolite facies and formed at depths of 5 - 10 km. The relative timing of mineralization is typically syn- to late-deformation and syn- to post-peak metamorphism. They are formed from low salinity, CO2-rich hydrothermal fluids with typically anomalous concentrations of CH4, N2, K, and S. Gold may also occur outside of veins within iron-rich sulphidized wall rock. PAGE 8-1 Exploration Neither Leagold nor Equinox have carried out any exploration at the Mine as of the date of this Technical Report. Exploration conducted by previous operators is documented in reports by RPA (2016, 2018) and Cube (2014). From October to December 2017, Brio conducted a 12-hole drilling program to explore the deposit at depth to test the potential for underground mining, and better define open pit boundaries. A summary of the drilling program is included in Section 10. 9.1 Exploration Potential The Mine remains the principal deposit in the district. Open-pit expansion potential exists along trend to the north and south, and underground mine potentisal exists down dip where mineralization has been intersected by widely-spaced drill holes. In addition to exploration potential near the Mine, the main shear zone that controls the gold-ore zone at the Mine extends over 15 km, in both directions, and to date has not been explored in detail. Historical drilling holes show significant gold intersections, as shown in Figure 9-1. PAGE 9-1 10.2 Sampling Method and Approach Historical drilli sampling by CVRD, Carpathian, and Brio is described by RPA (2015, 2018) and by Cube (2014) in their respective technical reports. The RC has a reliable sampling as described below. 10.2.1 Reverse Circulation Sampling MRDM geologists supervised RC sampling. Samples were taken at 1.5 m intervals, collected at the discharge cyclone, then passed through a three-tier Jones Riffle Splitter before a split was collected into a pre-labelled sample bag. The cyclone and splitter were cleaned after each sample, between each rod change, and between holes. The samples collected from each hole were arranged sequentially and transported to the sample room at the camp for preparation. PAGE 10-3 11.1.1 Sample Security Samples are collected by a trained sampler under the supervision of a technician or a geologist, with all quality assurance and quality control (QA/QC) samples inserted within a sequentially numbered sequence and recorded. The samples are shipped by truck directly to the Mine laboratory using the Mine Geology departments' own transport service. The samples are checked in with the submission sheet; if any problem is identified with the samples, the laboratory notifies the site geologists for clarification on the discrepancies. The sample rejects are stored in the laboratory and are returned to the department of geology or discarded with prior authorization. Equinox finds that the sampling methods, the chain-of-custody procedures, and analytical techniques are appropriate and meet acceptable industry standards. In the Authors' opinion, the sample preparation, analysis, and security procedures are adequate for use in estimating Mineral Resources. PAGE 11-1 Quality Assurance/Quality Control The QA/QC program used in the RC drilling campaign included inserting Certified Reference Material (CRM), blanks, and duplicates (both preparation and pulp) into the sample stream at the frequency summarized in Table 11-1. QA/QC sample types and insertion rates are summarized in Table 11-2. a total of 7,721 QA/QC samples were submitted from June 2018 to December 2020 for the RC sample program. Laboratory performance is also assessed using check assays (pulps sent to alternate labs) and participation in the Proficiency Test Program. The performance of the QA/QC samples is monitored and reviewed monthly, and in the case of failures the sample batches are reanalyzed by the lab to ensure compliance with industry standards to support a Mineral Resource estimate. In the authors' opinion, the protocols in place meet industry standards and are sufficient to produce a resource model. Table 11-1: Laboratory QA/QC Protocols QA/QC Type Certified Reference Material CRM samples are materials of known gold content used to check and quantify the analytical accuracy of assay laboratories. Brio, Leagold, and Equinox Gold used thirteen types of gold CRMs purchased from Geostats Pty Ltd. (Geostats), O'Connor, Western Australia. Their certified gold content is determined by extensive round-robin assaying at accredited assay laboratories (Geostat, n.d.). The certified blanks were purchased from Quimica Brasileira, Brazil. The variation from the CRM's mean value in standard deviations (SD) defines the QA/QC variance and is used to determine the acceptability of the CRM sample assay. Results within ±2 SDs are considered acceptable. The certified values, acceptable ranges for analyses, and other statistics for the CRMs are presented in Table 11-3. Approximately 50 to 65 g of sample material is submitted per CRM sample. Table 11-3: Certified Reference Materials CRM Notes: "z-Score" on the vertical axis is a normalization of the SD (1 SD = 1 z-score unit), allowing results for different standards to be plotted on the same chart. Figure 11-2: CRM Results (±5 z-score) Over Time for the Jun 2018 to Dec 2020 RC Program 11.2.2 Blanks Coarse blank samples barren of gold were inserted into the sample stream to check for potential laboratory contamination, drift, or tampering. The lower detection limit was 0.04 g/t Au. A failure limit was defined as greater than 0.08 g/t Au which is twice the lower detection limit. In processing and analyzing the blank standard for gold, the Mine laboratory performed very well. Of the 1,469 blanks analyzed, only seven samples reported results above the lower detection limit for gold (0.5% failure rate), and the highest gold value reported was 0.246 g/t Au. Details of the performance of blanks are provided in Figure 11-3. PAGE 11-6 Figure 11-3: Coarse Blanks Submitted with RC Samples 11.2.3 Duplicate Samples Field duplicates were prepared for insertion into the sample stream to monitor sample homogeneity and laboratory precision. Field duplicates were taken by preparing two quarter-split samples from one sample interval and sending them to the Mine laboratory for analysis. Preparation duplicates were prepared by producing two pulps from the RC samples after being crushed to less than 2 mm. Comparing the results from the preparation duplicate pairs indicates the efficacy of the sample preparation procedure for producing a representative sample for analysis. The duplicate samples are compared by computing the absolute relative difference between the two analyses from each pair and by preparing scatter plots and histograms. Absolute relative difference is the absolute value of the difference in the two analyses, divided by the average of the two analyses and expressed as a percent. Field-duplicate assays show moderate variability between the two quarter-split samples. In all, 32.41% of the pairs show more than 30% variation in returned gold grade, most notably at lowest grade ranges (43.77% <0.10 ppm Au). Variability at this lower grade range is not deemed a concern as it is significantly below the mining cut-off grade. Other grade ranges that are representative of ore grades demonstrated an amount of natural heterogeneity on the scale of quarter-split sample, indicating that splitting and sampling are generally reliable, despite this natural heterogeneity. No significant biases were evidenced, and a good correlation was established (R2 = 0.9255). The results are provided in Table 11-5 and Figure 11-4. PAGE 11-7 Figure 11-4: RC Field Duplicate Au Assays Preparation duplicates show higher correlation (R2 = 0.9767) and lower dispersion (SD = 23.70%) than field duplicates, probably attributed to the more homogeneous particle size (85% <2 mm). However, there is a high failure rate, partly associated with lower grades (38.02% less than 10 g/t Au). For the range of grades above the cut-off grade (0.33 g/t Au), it is recommended that the secondary crushing product be close to 90% <2 mm, due to the encapsulation of gold by sulphides and arsenopyrite. Results of the preparation duplicates are shown in Figure 11-5. Subjecting the precision results to the Thompson-Howarth criteria, the best precisions for a cut-off grade of 0.33 g/t considering all the data including the outliers are 18.29% (field duplicate) and 10.13% (preparation duplicate). The Figure 11-6 shows the Thompson-Howarth criteria considering a restriction of the data from the cut-off grade of 0.33 g/t to 2g/t, without the outliers influence. The precision are 19.75% (field duplicate) and 11.45% (preparation duplicate). PAGE 11-8 Proficiency Test Program Annually, the MRDM laboratory participates in Proficiency Testing Programs in gold ores to evaluate the technical competence and accuracy of the results provided according to validated methods. This type of program consists of an analytical round with several national and international laboratories. The results issued are submitted to a rigorous statistical treatment to standardize and certify as a true value the gold results for a pair of samples analyzed by participating laboratories. The providers are the Instituto de Tecnologia August Kekule (ITAK), and Centro Tecnológico de Referência SulAmericano (CTRS), ISO/IEC 17043:2011-accredited Brazilian providers. These institutions support developing and revising standard techniques with ISO standards, through the Brazilian Association of Technical Standards (ABNT), the Committee for International Mining Standardization (CONIN), and the Brazilian Mining Institute (IBRAM). Proficiency Testing Programs are part of the European Proficiency Testing Schemes as a provider of Interlaboratory Programs, which is supported by the European Co-operation for Accreditation (EA) and European Federation of National Associations of Measurement, Testing and Analytical Laboratories (EUROLAB). The interpretation of results regarding accuracy was based on two criteria: the first, for compatibility between the results of different laboratories (Youden ellipse); the second through a standardized tool recommended by ISO (z-score), the latter being best applied because it is a statistical measure that indicates how many SDs the value found by the participating laboratory is above or below the certified value. So, a positive z-score indicates data above the certified value, while a negative value indicates data below the certified value. The interpretation of the value of the z-score index is described below: | z | ≤ 1 EXCELLENT result 2 <| z | <3 QUESTIONABLE result | z | ≥ 3 UNSATISFACTORY result The Youden ellipse shown in Figure 11-12 is constructed for a pair of samples, and a dot represents each laboratory. Its structure is traced in such a way that any point has the same probability of being within the ellipse, with a 95% degree of confidence being established. Usually, the points are located inside the ellipse. The ellipse's inclination and its shape depend on the dispersion of the pair of samples from the group of laboratories evaluated. The ellipse is divided into quadrants, with lines at the certified values of the two standard samples used along the x and y axes. Points found in the upper-right and lower-left quadrants represent laboratories that may be incurring systematic errors. However, the presence of dots in the upper-left and lower-right quadrants is interpreted as the occurrence of random errors. Values outside the Youden ellipse are characterized as outliers, and have a special cause of variation. In general, the Youden ellipse obtained for gold analyses showed normal distribution, uniform dispersion, and SATISFACTORY performance for gold analysis (according to the Youden evaluation criterion), with the pairs of samples plotting in Quadrant I of the 95% confidence ellipse (Figure 11-12). No outlier results were identified. PAGE 11-14 Security A security fence surrounds the mine site, and it has controlled access at a gatehouse with full-time security personnel. At site, samples were under the control of MRDM or drilling contractor employees at all times. Sample handling procedures at the drill rig are described in Section 11.1.1. Drilling company personnel delivered samples daily to MRDM personnel at the Mine site's sample processing facility. Only MRDM or drilling contractor personnel were authorized to be at the drill sites and sample processing facility. After logging and sampling, the samples were prepared for shipment to MRDM's internal laboratory. The samples were placed in large plastic shipping sacks, accompanied by documentation of the batch and samples, loaded onto a pickup owned and driven by the responsible operations technician, and taken to the laboratory. Samples were under constant supervision during transport. Industry-standard chain-of-custody and work-order forms are used in sample transfers. Appropriate steps are taken to protect the integrity of samples at all processing stages. After completing analyses, data are sent securely via electronic transmission to the mine and geology teams. After sample analyses are complete, pulp and reject materials are discarded or returned to a specific area of the geology department. In the authors' opinion, sample preparation, analysis, and the security and confidentiality protocols in use are adequate, generally conform to industry standards, and suitable for use in a Mineral Resource estimate. PAGE 11-17 Historical and current operational overview Process plant feed comprises 40% North Pit, 30% Central Pit, 30% South Pit, representing zones in the pit. Each pit zone has the following characteristics: • North Pit Zone: with high-grade ore (>1.2 g/t Au) and the highest Bond Work index (BWi) between the zones • Central Pit Zone: with low-grade (0.33 - 0.80 g/t Au) and medium grade (0.80 - 1.2 g/t Au) ores, containing inert carbonaceous material or graphite, arsenopyrite, and pyrrhotite at relatively low concentrations • South Pit zone: mainly oxidized low-grade ore (0.33 - 0.80 g/t Au) Since 2014, the main operational restrictions of the plant were the lack of available water and power supply; these issues have since been solved. Currently, the plant operates with a water volume of 630 m3/h: • • 45% process water recirculated from the TSF. Diesel generators are no longer needed. Following upgrades to the local power grid at the end of the first quarter of 2019, MRDM now operates with electrical power from distribution lines operated by CEMIG; this change allowed plant throughput to be increased from 290 t/h to 342 t/h by enabling operation at a higher steel-ball load in the mill. The original metallurgical recovery forecast was 91% at a particle size fraction of P80 53 µm. However, the plant currently operates at 70% minus 53 µm (P80 106 µm), recovering 87% on average. A series of process improvements were completed between 2018 and 2020 including steel ball resizing and reloading, lead nitrate addition, enhanced oxygen addition, sparging fine carbon recovery optimization, adding cyanide in the elutions, and nickel mobilization during electrowinning. Despite the feed grade lowering each year, the processing circuit has been improved incrementally in various areas to extract gold more efficiently. Production history is summarized in Table 13-1. Figure 13-1: Capacity and Recovery Improvement Process production throughput was limited or halted due to a lack of processing water several times including in 2016, 2017, 2018, and 2019. Despite completing the approximately 4 Mm3 WSF at the start of 2018, the catchment area of the dam was significantly affected by farming activities, which slowed down the filling of the dam. The 2020 rainy season has significantly increased the volume of water stored in the WSF, making water fully available and allowing the plant to maintain its operations continuously. Production shortfalls in 2019 were also due in part to an infraction notice from a regulator. The notice was related to historical interpretation of the LO (License to Operate) regarding TSF raise methods. It was not material and has been resolved. PAGE 13-2 Process Step Changes After a series of process testworks and process improvements in the Plant in 2019 and 2020, the process team could measure an improvement in the metallurgical recovery of approximately 9%, achieving 87% recovery with a lower standard deviation. Figure 13-2 shows these modifications and the respective gains. Figure 13-2: Process Improvements and the Recovery increase (%) The following details key step changes presented in Figure 13-2 are: • Improvements in both process throughout and metallurgical recovery resulted in a step change in recovery from a low of 76%. Grinding improvements led to the step change as the steel ball size was reduced in combination with an increase in the steel ball load due to increased power availability. This resulted in a finer grinding at higher throughput levels. • The TAC implementation increased recovery by approximately 3% due to improved cyanide dosage control at Tank 2. • The addition of lead nitrate to passivate higher solubility sulphide surfaces (pyrrhotite) improved both cyanide and oxygen consumption. • The North Pit ore reduced the recovery by about 3%; however, implementing an oxygen shear reactor in combination with oxygen sparging in the pre-aeration step, led to the increase of the DO concentration to approximately 12 mg/L in the pre-aeration tank, which improved passivation of thiocyanates and cyanicides, and increased the leach reaction. PAGE 13-3 Historical data A brief summary of the relevant testworks is presented in this Technical Report. Metallurgical testworks was conducted in four phases. CVRD conducted testing on samples of sulphide ore at the time it was operating the mine. CVRD collected six bulk samples from an underground exploration gallery and completed cyanide leach tests at various grind sizes. The samples ranged in grade from 1.57 g/t Au to 4.78 g/t Au. Column leach tests showed average gold recovery of 67% for a minus 2 mm crush size. In bottle roll tests, the gold extraction averaged 81% at a grind size of 74 µm and the recovery increased with finer grind sizes. A significant observation was that the sulphide ores responded reasonably well to cyanide leaching. In 2008, SGS-Geosol Brazil (SGS) conducted testworks using three composite samples from Areas III, IV, and V of the open pit. Cyanide leaching kinetics tests were conducted on a particle size of 80% passing (P80) of 75 µm. CIL tests were also conducted. The gold extraction ranged from 88.6% to 91.9% after 72 hours of leaching in the presence of activated carbon. In 2010, G&T Metallurgical Services Ltd. (G&T) conducted tests on eleven samples that represented oxide, transition, and fresh (sulphide) ore taken from various areas of the pit at varying gold grades. The testing by G&T included grinding, leaching, cyanide destruction, and sedimentation testworks in three series of leaching tests. The first series of tests were conducted using standard cyanide leach conditions. The second series of tests were conducted with lead nitrate added to the leaching tests, and the third series of leaching tests added both lead nitrate and activated carbon. Lead nitrate did not appear to improve the results. The average gold extraction was 91% after 72 hours of leaching at a particle size fraction of a P80 of 55 µm to 60 µm. The testworks showed that a target gold recovery of 90% can reasonably be achieved after 24 hours of leaching at a P80 of 55 µm. A fourth series of testworks were carried out by RDM´s process team with good results in 2019 and the plant process improvements were implemented in 2019 and in 2020. The metallurgical most recent series of testing are described as follows. 13.2.2 Residence Time Testworks After a series of bottle rolls testworks in 2019 with varying the leaching timing, it was decided in 2020 to transform the last Tanks 9 and 10, which used to be DETOX tanks, in the leaching tanks in order to increase the residence time to 27 hours adding more carbon stages to the CIL. The existing DETOX operation was then modified, using a sump box to receive the tailings. The reagents are dosed in this sump; therefore, cyanide destruction is now performed inside the pipeline that discharges tailings to the tailings dam. PAGE 13-4 Oxygen increase Testworks RDM used to be operated with oxygen injection using direct air injection spargers providing around 7 mg/L of dissolved oxygen in the pre-aeration tank. In 2020 a series of testworks with a new system was conduced by the process team, using a pump to recirculate the slurry and injects oxygen gas into a shear reactor installed at the pump outlet. The dissolved oxygen in the slurry in the pre-aeration step increased to approximately 12 mg/L. This increased the recovery by about 3% and stabilized the process, as shown in Figure 13-. Figure 13-3: Graph of the Oxygen System Benefits 13.2.4 Lead Nitrate Testworks In June 2019, after a series of bottle rolls and industrial scale testworks, the process team installed an automatic system to dose lead nitrate in the leaching circuit. It started with 30 g/t, and currently the process team has increased the dosage to 60 g/t, as more sulphide ore is being fed to the plant. With this testworks and process change, the metallurgical recovery increased by about 2%. Lead nitrate aids passivation of high-solubility sulphides such as pyrrhotite and arsenopyrite, by reacting and forming PbS on the sulphide surface, thereby reducing the consumption of oxygen and cyanide by these sulphides in an alkaline environment. PAGE 13-5 Mineral Resource Estimate Mineral Resources were estimated from a block model constructed by Equinox as of December 31, 2020, using the results of new grade-control drilling during 2019 and 2020. The QP audited the model and found that it was reasonably prepared and provided a good representation of the geologic data. Equinox summarizes the Mineral Resources exclusive of Mineral Reserves in Table 14-1 and inclusive of Mineral Reserves in Table 14-2, based on the end of December 2020 topographic surface. This Mineral Resource estimate conforms to CIM Definition Standards (2014). Table 14-1: Mineral Resources Summary (Exclusive of Reserves) - Decem