Overview

Deposit type

• Hydrothermal
• Vein / narrow vein

Summary:

Deposit Types
Ernesto, Lavrinha, Nosde and Japonês and Pau-a Pique deposits are described as a detachment style gold deposit that typically has the following characteristics:
• Gold mineralization is associated with low angle to flat detachment faults, generally with a normal (extensional) sense of movement that consistently places younger units over older units.
• Mineralization is commonly characterised by quartz-rich vein and veinlet zones (in the ±25% range) with magnetite or hematite, coarse euhedral pyrite (in the ±1% range), sericite, some clay mineral, some late stage calcite and gold. The gold is commonly associated with only very small amounts of silver.
• Mineralization is typically located along a 3 m to 8 m thick of mylonitic rocks of a detachment (or thrust) fault that intersects high angle structures, either faults or folds. The detachment is commonly within a deformed zone 10 m to 30 m thick.
• The continuity of the mineralization within the detachment zone is normally quite good, extending over 100 m.
• Detachment–style gold mineralization is in altered rock parallel to anticline axes and faults.
• Multiple styles of mineralization are common with local stacked mineralized zones.
• Fluid inclusion studies indicate temperatures of formation about 200°C to 250°C.

The Pau-a-Pique and Ernesto (Lower Trap) deposits are similar in that they both occur at the contact between the Aguapeí Group and the basement meta-tonalite. At both locations, the contact is associated with shear zones and hydrothermal alteration assemblages with pyrite, sericite and hematite. However, there are some differences between each deposit including the Ernesto deposit having a low-angle dip (±15°-25°), and being hosted in the contact between the Aguapei Group and metatonalite (Lower Trap) and areas of weakness within Aguapei Group. While Pau-a-Pique mineralization has a high-angle (±80°) and is hosted only in the contact of the Aguapei Group and metatonalite.

The Middle Trap in Ernesto and São Francisco deposits are similar in that they both occur within Aguapeí Group psammitic rocks affected by hydrothermal alteration resulting in assemblages rich in silica, sericite and hematite. The Ausenco (2010) report draws parallels between the shallow dipping Ernesto Deposit and detachment-style gold deposits in the south eastern California and to bedding plane parallel shears in Tarkwa sediments in Ghana. Reid et al. (2012) consider the São Francisco Mine (currently in care and maintenance and owned by a third party), located north of Ernesto, to be a shear hosted lode gold deposit. São Francisco is located approximately 60 km northwest of Ernesto and displays similar host Aguapeí Group lithologies and structural controls at the deformed basement/Aguapeí Group contact. São Francisco is considered by Reid et al. (2012) as epigenetic, structurally controlled, and composed of narrow, 1 cm to 5 cm wide, and quartz veins containing free gold. The veins, and vein systems and stockworks both parallel and crosscut the bedding planes and appear to represent separate but closely related mineralizing events. The São Francisco, Ernesto-Nosde_Lavrinha and Pau-a-Pique Deposits are broadly similar in host lithologies, structural style, alteration, and mineralization and all share characteristics of shear hosted lode gold deposits. At Lavrinha and Nosde, mineralization occurs within a schist sub-member of the Aguapei Group. Mineralization is often associated with narrow quartz vein and veinlets in phyllonitic matrix with strong sericitization and chloritization. The thickness and size of quartz veins are smaller than Ernesto and rarely exceed 1 m in true thickness. Pseudomorphs of pyrite and strong sericitization with the presence of quartz are good indicators for mineralization intervals. Strong foliation and kink-band structures disrupted mineralized shoots both along strike and down dip of the deposit. The style of mineralization and deposit type is very similar to Ernesto and detachment style faults are marked with pervasive alteration along the contacts and within a sericite schist package. Mineralization and alteration both developed in contact meta-arenite with sericite schist and also within the sericite schist.

Mineralization and Alteration
Ernesto Deposits
The Lower Trap consists of an intensely altered mylonitic zone developed along detachment structures between the Lavrinha tonalite and the feldspathic metasandstone of the Fortuna Formation. Alteration associated with gold mineralization within the mylonitic zone includes abundant quartz veins and veinlets with coarse-grained euhedral pyrite and fine-grained bipyramidal crystalline magnetite, along with visible gold. Additionally, there is fine-grained sericite, chlorite, specularite, and fissural hematite and limonite.

The presence of extensional faulting at the time of mineralization caused the alteration of the footwall tonalitic unit. The tonalite is extensively altered and historically logged as saprolite. However, the mineralogical composition of this altered footwall unit is completely different from the saprolite on the surface. The footwall saprolite is mainly composed of clay minerals produced by alteration of feldspar and mica from tonalite groundmass and gradually changes to weakly altered tonalite.

The Middle Trap is restricted to a permeable conglomeratic horizon, where it intersects dilation structures developed by folding and faulting. It comprises milky quartz veins with fresh and weathered pyrites, with sericite and chlorite alteration of the matrix and fissural hematite. This trap crops out in the Ernesto pit, and is intersected in drill holes at the Nosde and Lavrinha deposits.

The Upper Trap is widely developed in the Lavrinha and Nosde deposits, occurs in metapelitic rocks (hematite sericite schist) in dilation zones of the intensely deformed synclinal troughs. The Upper and Intermediate traps share similar alteration and mineralization suites. The Upper Trap seems to be eroded in the Ernesto deposit area.

The Bonus Trap consists of centimetre-thick cross-cutting quartz veins hosted by the upper metasandstone in the Nosde and Japonês deposits. These milky quartz veins include fresh and weathered pyrite and box works, along with visible gold. Hematite and limonite occur as fissure-filling and halos around the mineralized quartz veins.

Mining Methods

• Truck & Shovel / Loader

Summary:

Ernesto/Pau-a-Pique mine complex (“EPP”) is comprised of the following gold deposits: the Lavrinha open-pit mine (“Lavrinha”), the Ernesto open pit mine (“Ernesto”), the Pau-aPique underground mine (“Pau-a-Pique” or “PPQ”), the Japonês open pit mine, the Nosde open pit mine, and the near mine open pit prospects of Bananal North and Bananal South.

The Ernesto Project was revisited during 2018 and after careful evaluation, the company decided to start its mining operation using an open pit method instead of underground, which further de-risks the project.

In December 2019, the company started mining operations at the high-grade Ernesto mine. In November 12, 2020, the Ernesto open pit mine, part of the Ernesto/Pau-a-Pique mine complex (“EPP”) declared commercial production effective October 1, 2020.

During Q4 2023, the amount of ore mined showed a significant increase compared to Q4 2022, mainly due to accessing the ore body at the base of the Ernesto mine.

Comminution

Crushers and Mills

Summary:

Crushing
The loaded trucks from different areas of the mine unload the ore in several piles in the crushing square, thus allowing the blending of the typologies and control of the fed contents. The stacked ore is taken up by a loader that feeds the hopper of the vibratory grizzly, the latter with an average opening of 100 mm. The fraction retained in the grizzly feeds a 106-mm opening jaw crusher into the closed position. The maximum size of the material fed into the crusher is about 0.5 m. The crusher product, together with the passing fraction on the grizzly is driven by belt conveyors to the milling silo. The conveyor system is furnished with a scrap extractor and magnetic detector.

The operating criterion adopted in the primary crushing of EPP is to keep the feed hopper filled with material taken up by the loader, to keep the milling silo also full. Excess crushed material is stacked in an emergency stack and resumed as needed.

Milling
The new feed rate of the milling is modulated by the speed variation of the feeders installed under the silo. A scale installed on the mill feed belt conveyor monitors this operation. The discharge from the SAG mill is sent to the trommel of the mill itself, thus resulting in the retained fraction (pebbles), which returns to the mill feed, while the passing fraction flows to a pulp box, from which it is pumped to the cyclone battery, the overflow of which constitutes the milling product, while part of the underflow is sent to scalping sieving, and the passing fraction of it flows to the centrifugal concentrators. The remaining fraction of the underflow of the cyclones, as well as the fraction retained in the scalping sieving and tailings of the centrifugal concentrators return to the mill feed, as well as the tailings from the intensive leaching of the centrifuge concentrate. The milling operation has a system for real-time control and adjustment of operating parameters called Smart Control LEAF, developed by iSystems.

Processing

• Carbon re-activation kiln
• ACACIA reactor
• INCO sulfur dioxide/air process
• Crush & Screen plant
• Smelting
• Centrifugal concentrator
• Gravity separation
• Concentrate leach
• Agitated tank (VAT) leaching
• Carbon in leach (CIL)
• Carbon adsorption-desorption-recovery (ADR)
• AARL elution
• Dewatering
• Solvent Extraction & Electrowinning
• Cyanide (reagent)

Summary:

The Apoena Mines (EPP Complex) ore treatment flowchart consists of a primary crushing step, followed by a semi-autogenous milling step – SAG in a closed circuit with cyclones, in order to obtain a product with P80 of 0.106 mm. The milling circuit includes a gold gravimetric concentration step, formed by a scalping sieving of the underflow of cyclones, the passing fraction of which is routed to the gravimetric concentration in centrifuges, followed by intensive reactor leaching for processing the gravimetric concentrate. The overflow of cyclones, which is the product of the milling, then goes to a step of cleaning harmful, organic substances, in a linear sieve, with the undersize being directed to the step of pulp thickening. The thickened pulp is then leached with sodium cyanide (cyanidation), in a circuit with seven tanks in series and cascade arrangement, with a residence time of currently 16 hours, compared to 24 hours of the original design. This reduction is a consequence of the increase in the feed rate of the EPP plant. In this circuit, the addition of activated carbon is conducted, which runs through the circuit in countercurrent to adsorb the leached gold into the pulp. The charcoal charged with gold is subjected to elution, electrolysis, and casting, the latter resulting in the "bullion". The waste from the hydrometallurgical process is treated to reduce the residual cyanide, pursuant to the applicable environmental laws, to then be deposited in a dam.

Pre-leaching Thickening
The milling product with rated P80 of 0.106 mm is directed to a linear sieve for removal of harmful elements to leaching, such as organic material and possible coarse particles. Owing to the increase in the capacity of the milling circuit in the treatment of less tenacious typologies – shale sericite and mylonite, the pulp densification step started to include a cyclone prior to thickening. Thus, the passing fraction in the protective sieving started to be pumped to a new cyclone, the overflow of which then goes to the existing vertical thickener, while the underflow feeds a new stage of concentration in centrifuges, called scavenger. The thickener underflow along with the scavenger centrifuge tailings form a pulp with 50% solids by weight which is then routed to leaching.

Gravimetric Concentration
The EPP gold gravimetric concentration circuit was installed according to a classical configuration. In this circuit, 25% of the cyclone underflow is diverted to a scalping sieve with an opening of 3 mm, installed to remove coarse particles and organic contamination. While the oversize of this sieving returns to the mill, the undersize goes to feed the centrifugal concentrators, the tailings of which then return to the mill feed and the concentrates feed the fluidized bed cone of an intensive leaching reactor, "Intensive Cyanidation Unity" (ICU). Intensive leaching is carried out in batches and the obtained rich liquor is directed to the electrolysis step, where the concentrate generated in the cathodes, after filtration, is melted to form the bullion.

The original centrifuge considered in the EPP design had a capacity of up to 150 t/h of solids, while the reactor had a capacity of about 1.5 t of gravity concentrate. The intensive leaching residence time considered was 16 hours. Owing to the increase in the milling feed rate provided by the processing of ores such as shale sericite and mylonite, two additional centrifugal concentrators were installed. The larger equipment, with three times the capacity of the original, was installed in parallel to the then existing centrifuge, to treat the milling's circulating load. A smaller centrifuge, called scavenger, was installed to process the secondary cyclone underflow.

To adapt the leaching capacity of the reactor to the new conditions, the leaching time of ICU was reduced from 16 hours to 6 hours.

Leaching in Tanks (CIL)
The EPP carbon in leach (CIL) circuit consists of seven tanks, each with a capacity of 567 m3 . These tanks have mechanical stirring in order to produce internal pumping and pulp revolutions to provide better contact with the reagents – sodium cyanide and oxygen. In the first tank, the cyanide concentration is maintained around 130 mg/l. After purification, oxygen is injected through a radial system of rods, called Slamjet. Purification, or increase in oxygen concentration, is conducted to increase the reaction kinetics, thus compensating for the higher feed rates of the plant and, consequently, decrease the residence time of the pulp in the existing tanks. All tanks have an activated carbon concentration between 10 kg/m3 and 30 kg/m3 . The activated carbon, responsible for the adsorption of complexed gold, is retained in the tanks by means of inter-stage sieves, of the rotating cage scraper type. In this process, the movement of charcoal is prevented in the direction of the pulp current and moved, in countercurrent, with the aid of transfer pumps, for its enrichment, to the first tank of the circuit. The enriched charcoal is separated from the pulp by a vibrating sieve and sent to the final concentration operations, which are elution, electrolysis, and smelting.

Elution
The charcoal removed from the leach tanks in an amount of about 4 t presents between 1,000 to 1,500 g/t of gold. This charged carbon is directed to an acid wash step, performed on a fluidized bed column with a solution of about 3% w/v of hydrochloric acid. After acid washing and neutralization, the charcoal goes to another column where the gold is extracted from the charcoal by the Anglo American Research Laboratories (AARL) process. In this AARL circuit, a solution with a high concentration of sodium cyanide and caustic soda is injected into the column, which remains in contact with the charcoal for about 30 minutes. After this period, the elution itself begins, by injecting into the water column heated to 130 ºC to wash the desorbed gold. The solution obtained is stored in a rich solution tank to proceed to the electrolysis phase. At the end of the process, the charcoal is washed, cooled, and then returned to the leach tanks to begin the countercurrent enrichment process. Two batches of elution are performed daily. EPP has a thermal regeneration process of the eluted charcoal, but it is deactivated.

Electrolysis and Smelting
In EPP, the rich solution electrolysis step is conducted in a circuit with three electrolytic cells, which operate in parallel, so that there are equitable retention times in each cell. The electrolytic cell vats have eight cathodes and nine anodes. The volume of each cell is 1,300 L, being equipped with rectifiers, which provide voltage from 3.8 V to 4.5 V in direct current. Each batch of the reduction process lasts six hours and, at the end, the cathodes are removed and washed. The collected sludge is filtered, and the cake obtained mixed with the fluxes – sodium nitrate (1:0.6), borax (1:0.4), sodium carbonate (1:0.3), and silica (1:0.3). This mixture is transferred to a graphite crucible and then smelted in a kiln at a temperature of 1250 °C provided by liquefied petroleum gas (LPG). After complete smelting, the flux is poured into forms, where the slag is separated from the metal, the latter forming the bullion.

Cyanide Neutralization and Tailing Pumping Circuit
The waste from the leaching and adsorption circuit flows by gravity from the last tank of the CIL circuit to the cyanide neutralization circuit, also called Detox.

The EPP Detox circuit in the original Design consisted of two tanks with a volume of 110 m3 each.

Two reserve tanks of the same capacity were subsequently installed, in order to maintain the pulp residence time for increases in feed rate.

In this process, the cyanide residue present in the leach tailings is treated using the SO2/Air method, also called Inco process.

Water Supply

Summary:

Water Collection and Distribution
The Lavrinha stream ("Córrego Lavrinha"), located near the BR-174 highway, about 3.8 km from the processing plant, is the water source for the EPP Project.

The water is collected and directed by a channel to a "pump house" concrete box that is built in unevenness with respect to the channel. The Pump Room consists of two Imbil INI 50-315 100hp centrifugal pumps, with a rated flow of 70 m3 /h (maximum capacity of 120 m3 /h) and an Imbil BEW125-4 250hp multi-stage pump with a rated flow of 200 m3 /h. Water is pumped through a PN 16 8” HDPE pipe with a length of 3724.7 metres from the collection point to the new water tank located at the processing plant facilities.

The new water tank had three main water pumps that feed the following points:
• crushing;
• milling;
• preparation of reagents;
• elution;
• foundry;
• fuel station; and
• water treatment plant.

The firefighting system consists of electric and diesel water pumps that feed the hydrants and hose reels throughout the plant. The firefighting water jockey pump maintains the pressure in the main water ring piping for firefighting.

The process water is recovered from the tailings dam by two Imbil 125hp pumps, of INI150-400 model, through an HDPE pipe of 500 m in length and 8” diameter at a rated flow rate of 250 m3 /h.

The bottom of the raw water tank is reserved for use as fire water.

There are two water treatment plants in the Project, one in the Ernesto facility with a treatment capacity of 6 m3 /h and a second water treatment plant installed in the Pau-a-Pique field with a treatment capacity of 3 m3 /h. The two plants provide drinking water for the facilities of the kitchens, bathrooms, offices, and emergency showers throughout the Project.

The drinking water tank of the Ernesto plant has a capacity of approximately 100 m³. The treated water tank of the Pau-a-Pique unit has a capacity of approximately 50 m³. The relatively low retention time ensures that the treated water maintains drinking water standards.

Raw water required for the process is collected by pumping the Lavrinha River, at a distance of about 3 km from the operational site. The effective consumption of collected water is around 0.5 m³/t of processed ore. The main applications of raw water demand low salinity, low conductivity, and low presence of particulates. The main water uses in EPP circuit are as follows:
• Sealing for pumps.
• Sealing for the mill system.
• Cooling for the mill hydraulic system.
• Preparation of reagents.
• Acid washing of charcoal and elution.
• Safety equipment (eye wash).
• Dust control system.
• Firefighting.
• Drinking water treatment system.

Most of the water used in the plant comes from the recirculation process, via clarified water from the thickener or the dam supernatant. Information on the tailings dam is indicated in the infrastructure and environmental chapters of this document, which also includes the water balance of the plant.

Production

Personnel

Job Title	Name	Profile	Ref. Date
Director of Operations	Carlos Mamede		Sep 10, 2024
Processing Manager	Junior Cesar Santos Souza		Sep 10, 2024