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Ero Copper Announces Results of Optimized Feasibility Study for Boa Esperança Project – Doubles Life-of-Mine Copper Production

Resource Estimates Economic Studies

TSX: ERO NYSE: ERO

September 28, 2021

Ero Copper Announces Results of Optimized Feasibility Study for Boa Esperança Project – Doubles Life-of-Mine Copper Production

(all amounts in US dollars, unless otherwise noted)

Vancouver, British Columbia – Ero Copper Corp. (TSX: ERO, NYSE: ERO) (“Ero” or the “Company”) is pleased to announce the results of its optimized Feasibility Study (the "2021 Feasibility Study") on the Boa Esperança Copper Project ("Boa" or the "Project"), located in Pará State, Brazil.

HIGHLIGHTS

  • 41.8% after-tax internal rate of return ("IRR") and $380 million after-tax net present value (8%) based on Consensus Copper Price (as defined below) and 5.00 BRL:USD exchange rate;
  • Doubled life-of-mine ("LOM") copper production to approximately 326,000 tonnes from 163,000 tonnes in the 2017 Study (as defined below) with increased mine life of twelve years;
  • Mine life of twelve years supported by updated proven mineral reserves of 30.7 million tonnes at 0.89% copper and probable mineral reserves of 12.4 million tonnes at 0.67% copper, containing a total of 356.6 thousand tonnes of copper, a 93% increase in contained copper as compared to the 2017 Study (as defined below);
  • Low capital-intensity of approximately $8,400 per tonne of copper produced annually over the first 5 years of the Project resulting in rapid payback of 1.4 years at Consensus Copper Price;
  • Significant exploration upside identified within an under-explored area within the final pit limits, known as the "Gap Zone", expected to enhance the Project by (i) confirming continuity of mineralization between near-surface high-grade zones and high-grade zones near the pit limits at depth; and, (ii) converting material currently classified as waste into mineral resources. Subsequent to August 31, 2021, or the effective date of the mineral resource and mineral reserve estimates in the 2021 Feasibility Study (the “Effective Date”), ten exploration holes were drilled in the Gap Zone, all of which showed mineralization. To date, assay results have been received for three of these holes. Results are highlighted by hole BSPD-166 that intercepted 21.2 meters grading 0.98% copper and 15.3 meters grading 1.25% copper and BSPD-169 that intercepted 64.9 meters grade 0.86% copper including 15.0 meters grading 1.40% copper; and
  • Detailed engineering design efforts are currently underway with early construction works expected to commence during H1 2022, subject to the approval of Ero's Board of Directors.

1 Ero Copper Corp

2021 FEASIBILITY STUDY SUMMARY

General

Type of Operation Open Pit

Mine Lifeyears12
Mill ThroughputMtpa4.0
Total Tonnes Processedkt43,052
Life-of-Mine Strip Ratiowaste:ore3.7
Copper Head Grade% Cu0.83 %
Metallurgical Recovery%91.3 %

First Five Years of Production

Average Annual Recovered Copperkt35
C1 Cash Cost(1)$/lb Cu produced$1.12
Total Recovered Copper Productionkt174

Life-of-Mine Production

Average Annual Recovered Copperkt27
C1 Cash Cost(1)$/lb Cu produced$1.36
Total Recovered Copper Productionkt326

Financial Highlights

Copper Price $/lb Consensus Copper Price(2) Foreign Exchange Rate USD:BRL 5.00 Initial Capital $M $294 Sustaining Capital $M $196 After-Tax Net Present Value (8%) $M $380 After-Tax Internal Rate of Return % 41.8 % After-Tax Payback Period years 1.4

(1) C1 Cash Cost is a non-IFRS Measure. Please refer to the Notes section of this press release for a discussion of non-IFRS Measures.

(2) Consensus Copper Price forecast is based on the average analyst copper price estimates from 26 financial institutions as of the Effective Date, resulting in $3.80 per pound in 2024, $3.95 per pound in 2025 and $3.40 per pound in 2026 and thereafter.

SENSITIVITY OF ECONOMIC RESULTS TO COPPER PRICE (USD/LB)

67.9%

58.7% $880 48.8% $707 41.8% 38.0% $534 25.5% $380 $361

$188

Consensus $3.00 $3.50 $4.00 $4.50 $5.00 Copper Price

After-Tax Net Present Value (8%, US$M) After-Tax IRR

2 Ero Copper Corp

Commenting on the results, David Strang, CEO, stated, “The Boa Esperança Project is the most recent example of our team's commitment and outstanding track record of creating shareholder value from our existing portfolio, and we could not be more excited about the outcome of these efforts. We started the re-evaluation of Boa from the ground up, beginning with a complete review of the mineral resource calculations that identified significant upside opportunities on which to build a new vision for Boa.

“By re-logging core, focusing our efforts on geologic modelling and optimizing the mine sequence, we were able to identify a superior mine plan capable of supporting a much larger operation by pulling forward high-grade mineralization in the production plan. The result of this work is significantly higher annual copper production averaging approximately 35,000 over the first five years of the mine's life, a very attractive payback of 1.4 years and a 41.8% internal rate of return. Further, we see potential for additional value generation through ongoing exploration within the newly designed final pit shell.

“Our near-term focus will be targeting exploration in an area referred to as the Gap Zone, where we currently have four drill rigs operating. The Gap Zone is a sizeable target area within the current pit shell where there has been limited historic drilling. As a result, material mined from this zone, which is currently included in the later phases of the mine plan, is largely treated as waste. While early in the program, the ten holes we have drilled within the Gap Zone subsequent to the cut-off date of the 2021 Feasibility Study show mineralized zones in the areas where we would expect to see extensions and continuity of mineralization. With continued exploration success, we see potential to meaningfully increase the mine's production profile beyond year five of the current life-of-mine plan.

"Our excitement around our organic growth initiatives, including the delivery of the Boa Esperança Project and production growth at the MCSA Mining Complex, continues to build as we establish a clear path to doubling our copper production profile over the coming years while continuing to generate peer- leading returns on invested capital. With a robust balance sheet and strong cash flow generation, we are well-positioned to execute on our growth strategy and continue delivering shareholder value."

3 Ero Copper Corp

GAP ZONE EXPLORATION SUCCESS Subsequent to the Effective Date, ten exploration drill holes were drilled within the Gap Zone, all of which show mineralization. To date, assay results have been received for three of these holes. Results are highlighted by hole BSPD-166 that intercepted 21.2 meters grading 0.98% copper and 15.3 meters grading 1.25% copper, including 6.5 meters grading 2.46% copper, hole BSPD-169 that intercepted 64.9 meters grade 0.86% copper, including 15.0 meters grading 1.40% copper and hole BSPD-175 that intercepted 14.1 meters grading 0.73% copper including 5.7 meters grading 1.59% copper. Additional mineralized intercepts from within these holes are pending assay results.

Continued positive exploration results within the Gap Zone are expected to further enhance the Project by (i) confirming continuity of mineralization between near-surface high-grade zones and high-grade zones near the pit limits at depth; and, (ii) converting material currently classified and mined as waste into mineral resources. The Company expects the Gap Zone to contribute to increased copper production beyond year five of the mine plan.

Gap Zone drill results outlined in this press release, including drill collar locations, are shown below in Figure 1 and can be viewed on the Company’s Boa Esperança project tour and interactive threedimensional ("3D") model, which can be accessed via the Company’s VRIFY Technology Inc. (“VRIFY”) project page (www.vrify.com/companies/ero-copper-corp) or via VRIFY directly (www.vrify.com).

4 Ero Copper Corp

Hole ID From (m) To (m) Length (m) Cu (%)

GAP Zone - Assay Results

BSPD-16631.044.013.00.25
and125.4141.315.90.44
and174.0179.25.21.27
and189.7200.610.90.67
and339.5360.721.20.98
including339.5343.33.92.78
and383.5398.815.31.25
including386.3392.86.52.46
and435.4445.610.31.27
including435.4439.84.42.21
and467.8476.68.80.39
BSPD-169317.2382.064.90.86
including346.5354.98.41.46
and including367.0382.015.01.40
BSPD-175336.8350.814.10.73
including345.1350.85.71.59
and401.0438.037.00.20

GAP Zone - Additional Mineralized Intervals for Above Drill Holes (Assay Results Pending)

BSPD-169112.0119.07.0assays pending
and158.5183.024.5assays pending
and201.0263.062.0assays pending
and484.0499.015.0assays pending
and509.0536.027.0assays pending
BSPD-175101.0117.916.9assays pending
and127.0138.011.0assays pending
and185.0192.57.5assays pending
and203.8220.716.9assays pending
and302.0320.318.3assays pending

(1) Mineralized intercepts below cut-off grade of 0.20% copper not reported. Drill holes were drilled from surface using diamond core drill rigs. The length of intercept may not represent the true width of mineralization. Values may not add up due to rounding. From, to and mineralized intercepts are rounded to the nearest tenth of a meter. The seven remaining drill holes from the Gap Zone drilling campaign are pending assay results in their entirety.

Gap Zone drill results from BSPD-166, BSPD-169 and BSPD-175, as referenced herein, reflects mineralization not captured in the Company's NI 43-101 (as defined below) compliant mineral resource and mineral reserve models developed for the 2021 Feasibility Study. There has been insufficient work and analysis surrounding Gap Zone drilling to define a mineral resource and it is uncertain if further exploration and analysis will result in such targets being delineated as a mineral resource.

5 Ero Copper Corp

Figure 1 shows high-grade and low-grade mineralization, as well as the Gap Zone exploration target area within the final pit design of the Project. Figure 2 highlights recent Gap Zone drilling results.

The center of the final pit design is located at UTM Easting 450722.00 and UTM Northing 9241657.00. Boa Esperança mineralization based on data compilation work which includes review of geological controls, structural analysis and copper mineralization identified during the Company’s technical programs. The interpretation and boundary limits do not imply continuity of mineralization or actual thickness of mineralization. Mineral resources which are not mineral reserves do not have demonstrated economic viability.

Figure 1: Boa Esperança VRIFY 3D Model, Plan View looking North (Ero Copper, 2021)

6 Ero Copper Corp

The center of the final pit design is located at UTM Easting 450722.00 and UTM Northing 9241657.00. The GAP Zone volume is shown to demonstrate a future area of exploration within the Boa Esperança final pit design. The shape is based on data compilation work which includes review of geological controls and structural analysis during the Company’s technical programs. The interpretation and boundary limits do not imply continuity of mineralization or actual thickness of mineralization.

Figure 2: Boa Esperança VRIFY 3D Model, Gap Zone Results, view looking North (Ero Copper, 2021)

7 Ero Copper Corp

MINERAL RESERVES & RESOURCES, 2021

Tonnes Grade Contained Cu (000s) (Cu %) (kt)

Mineral Reserves

Proven Reserves30,6740.89273.2
Probable Reserves12,3780.6783.3
Proven & Probable Reserves43,0520.83356.6

Mineral Resources (Pit Constrained, inclusive of Reserves)

Measured Resources (High-Grade)7,1172.16153.6
Indicated Resources (High-Grade)1,6612.2737.6
Measured & Indicated Resources (High-Grade)8,7782.18191.3
Measured Resources (Low-Grade)25,4760.60152.0
Indicated Resources (Low-Grade)13,4340.5168.4
Measured & Indicated Resources (Low-Grade)38,9090.57220.4
Total Measured & Indicated Resources47,6870.86411.7

Inferred Resources

Inferred Resources (Pit Constrained High-Grade)402.691.1
Inferred Resources (Pit Constrained Low-Grade)5140.492.5
Inferred Resources (Pit Constrained)5550.653.6
Inferred Resources (Unconstrained High-Grade Outside Pit Limits)1,3542.2430.4
Inferred Resources (Unconstrained Low-Grade Outside Pit Limits)9,6810.6058.2
Inferred Resources (Unconstrained Mineralization Outside Pit)11,0350.8088.6
Total Inferred Resources11,5900.8092.2

(1) Mineral reserves and mineral resources have an effective date of August 31, 2021.

(2) Stated mineral resources are inclusive of mineral reserves. All figures have been rounded to the relative accuracy of the estimates. Summed amounts may not add due to rounding. High-grade and low-grade mineral resources defined as greater than or equal to 1.00% copper and less than 1.00% copper, respectively.

(3) A 3D geologic model was developed for the Boa Esperança Project. Geologically constrained copper grade shells were developed using a copper cut-off grade of 0.20% and 0.51% for pit constrained and unconstrained mineral resources, respectively, to generate a 3D mineralization model of the Boa Esperança Project. Within grade shells, mineral resources were estimated using ordinary kriging within a 2.0 meter by 2.0 meter by 4.0 meter block size. Open pit constrained, unconstrained and marginal cut-off grades are based upon a copper price of US$6,400 per tonne with cost parameters appropriate to the deposit. The mineral resource estimates were prepared in accordance with the Canadian Institute of Mining, Metallurgy and Petroleum (“CIM”) Definition Standards for Mineral Resources and Mineral Reserves, adopted by the CIM Council on May 10, 2014 (the “CIM Standards”), and the CIM Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines, adopted by CIM Council on November 29, 2019 (the ‘CIM Guidelines”), using geostatistical and/or classical methods, plus economic and mining parameters appropriate to the deposit.

(4) Mineral reserve estimates were prepared in accordance with the CIM Standards and the CIM Guidelines, using geostatistical and/or classical methods, plus economic and mining parameters appropriate for the deposit. Mineral reserves are based on a long-term copper price of US$6,613 per tonne; concentrate grade of 27% copper; average metallurgical recoveries of 91.3%; copper concentrate logistics costs of US$108.20 per wet metric tonne ("wmt"); transport losses of 0.2%; copper concentrate treatment charges of US$59.50 per dry metric tonne ("dmt"), refining charges of U$0.0595 per pound of copper; copper payability of 96.3%; average mining cost of US$2.47 per tonne mined; processing cost of US$7.74 per tonne processed and G&A costs of US$3.83 per tonne processed; average pit slope angles that range from 30º for saprolite to 50º for fresh rock and a 2% CFEM government royalty.

Mineral resources which are not mineral reserves do not have demonstrated economic viability. Please refer to the Technical and Scientific section of this press release for additional information.

8 Ero Copper Corp

MINERAL RESERVE COMPARISON TO 2017 STUDY

2021 Feasibility Study(1,2,3)2017 Study(4)Change
TonnesGrade Contained Cu TonnesGrade Contained Cu Contained Cu
(000s)(Cu %)(kt)(000s)(Cu %)(kt)(kt)%
Proven Reserves30,6740.89273.2 18,5280.96178.195.153 %
Probable Reserves12,3780.6783.39750.727.076.31,091 %
Proven & Probable Reserves43,0520.83356.6 19,5030.95185.1171.593 %

(1) Mineral reserves have an effective date of August 31, 2021.

(2) All figures have been rounded to the relative accuracy of the estimates. Summed amounts may not add due to rounding.

(3) Mineral reserve estimates were prepared in accordance with the CIM Standards and the CIM Guidelines, using geostatistical and/or classical methods, plus economic and mining parameters appropriate for the deposit. Mineral reserves are based on a long-term copper price of US$6,613 per tonne; concentrate grade of 27% copper; average metallurgical recoveries of 91.3%; copper concentrate logistics costs of US$108.20 per wmt; transport losses of 0.2%; copper concentrate treatment charges of US$59.50 per dmt, refining charges of U$0.0595 per pound of copper; copper payability of 96.3%; average mining cost of US$2.47 per tonne mined; processing cost of US$7.74 per tonne processed and G&A costs of US$3.83 per tonne processed; average pit slope angles that range from 30º for saprolite to 50º for fresh rock and a 2% CFEM government royalty.

(4) Please refer to the 2017 Study for additional technical and scientific information.

Please refer to the Technical and Scientific section of this press release for additional information.

9 Ero Copper Corp

TSX: ERO NYSE: ERO

LIFE-OF-MINE PRODUCTION PLAN AND CASH FLOWS

Unit LOM 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 2035 2036 Mining Operations

Ore Minedkt43,052—32,3124,2454,1484,1264,4003,8533,1534,0433,9034,1703,2671,429—
Grade Mined% Cu0.83—1.491.301.271.050.760.790.720.520.550.640.620.921.11—
Waste Minedkt160,0253,0178,0508,0558,112 14,957 15,874 15,600 15,912 16,160 15,957 16,097 13,7507,0531,430—
Total Minedkt203,0773,0178,054 10,367 12,357 19,104 20,000 20,000 19,765 19,313 20,000 20,000 17,921 10,3202,859—

Milling Operations(*)

Ore Processedkt43,052——2,1823,9904,0004,0004,0004,0004,0004,0004,0004,0003,4511,429—
Grade Processed% Cu0.83——1.341.331.080.770.820.700.490.560.640.630.901.11—
Metallurgical Recovery%91.3——93.292.892.190.691.890.787.289.990.491.291.391.5—
Cu in Concentratekt326——274940283026172023232814—

Operating Costs

Mining$M($407)$—$—($23)($28)($31)($44)($42)($27)($37)($35)($42)($44)($39)($15)$—
Process(2)$M($328)$—$—($17)($30)($31)($31)($31)($31)($31)($31)($31)($31)($26)($11)$—
Operational Support$M($42)$—$—($2)($4)($4)($4)($4)($4)($4)($4)($4)($4)($3)($1)$—
G&A$M($24)$—$—($1)($2)($2)($2)($2)($2)($2)($2)($2)($2)($2)($1)$—
TC/RCs(1)$M($40)$—$—($3)($6)($5)($3)($4)($3)($2)($2)($3)($3)($3)($2)$—
Royalty$M($44)$—$—($4)($8)($5)($4)($4)($3)($2)($3)($3)($3)($4)($2)$—

Transport Costs

Land Freight & Handling $M ($115) $— $— ($10) ($17) ($14) ($10) ($11) ($9) ($6) ($7) ($8) ($8) ($10) ($5) $— Sea Freight $M ($80) $— $— ($7) ($12) ($10) ($7) ($7) ($6) ($4) ($5) ($6) ($6) ($7) ($4) $—

Unit Costs

C1 Cash Costs(3) $/lb $1.36 $— $— $0.96 $0.85 $1.03 $1.55 $1.42 $1.37 $2.16 $1.85 $1.79 $1.83 $1.38 $1.14 $—

Capital Expenditures

Initial Capital$M($294)($75)($170)($49)$—$—$—$—$—$—$—$—$—$—$—$—
Sustaining Capital$M($196)$—$—($7)($19)($24)($15)($24)($51)($12)($22)($10)($13)$—$—$—
Closure Costs$M($24)$—$—$—$—$—$—$—$—$—$—$—$—$—$—($24)
Salvage Value$M$7$—$—$—$—$—$—$—$—$—$—$—$—$—$—$7

(*) Milling Operations reflect timing adjustments related to run-of-mine stockpile handling. Summed amounts may not add due to rounding.

(1) TC/RCs defined as treatment charges and refining charges.

(2) Process includes mill operating and maintenance expenses as well as costs related to dry stack tailings.

(3) C1 Cash Cost is a non-IFRS Measure. Please refer to the Notes section of this press release for a detailed definition.

10 Ero Copper Corp 625 Howe Street | Suite 1050 | Vancouver | BC | V6C 2T6 | Canada TECHNICAL AND SCIENTIFIC INFORMATION

Permitting

The Economic Exploitation Plan (PAE) for the Project was ratified in 2012 and subsequently renewed in 2013. The Company received the Installation License (LI) in August 2021, which will allow for the commencement of surface and civil construction activities in H1 2022. A formal request with the Secretaria de Estado de Meio Ambiente e Sustentabilidade ("SEMAS") will be made to incorporate changes in the Project's scope as outlined in the 2021 Feasibility Study. SEMAS is the agency responsible for approval of the Operating License (LO) for the Project, which is planned to be issued at the time of commercial production.

Mineral Resources

Block model tonnage and grade estimates for the Project were classified according to the CIM Standards and the CIM Guidelines by Mr. Emerson Ricardo Re, RM CMC (0138) and MAusIMM (CP) (305892), an employee of Ero Copper Corp. and a qualified person as such term is defined under National Instrument 43-101, Standards of Disclosure for Mineral Projects ("NI 43-101").

A 3D geologic model was developed for the Project. Geologically constrained grade shells were developed using various copper cut-off grades to generate a 3D mineralization model of the Project. Within the grade shells, mineral resources were estimated using ordinary kriging within a 2.0 meter by 2.0 meter by 4.0 meter block size. Within the optimized resource open pit limits, a cut-off grade of 0.20% copper was applied based upon a copper price of US$6,400 per tonne, net smelter return ("NSR") of 94.53%, average metallurgical recoveries of 90.7%, mining recovery of 95.0%, dilution of 5.0%, mining costs of US$3.10 per tonne mined run of mine ("ROM"), processing and transportation costs of US$5.65 per tonne ROM, and G&A costs of US$2.66 per tonne ROM. Unconstrained inferred mineral resources have been stated at a cut-off grade of 0.51% copper with a marginal cut-off grade of 0.32% copper based upon a copper price of US$6,400 per tonne, NSR of 94.53%, mining recovery of 100%, average metallurgical recoveries of 90.7%, mining costs of US$14.71 per tonne ROM, processing and transportation costs of US$5.70 per tonne ROM, and G&A costs of US$2.60 per tonne ROM. Stated mineral resources estimates are inclusive of mineral reserves.

The mineral resource effective date is August 31, 2021.

Mineral Reserves

The mineral reserves for the Project are derived from the Measured and Indicated mineral resources as defined within the resource block model following the application of economic and other modifying factors further described below. Inferred mineral resources, where unavoidably mined within a defined mining shape have been assigned zero grade. Dilution occurring from Indicated resource blocks were assigned grade based upon the current mineral resource grade of the blocks included in the dilution envelope. Mineral reserves were classified according to the CIM Standards and the CIM Guidelines by Mr. Carlos Guzman, RM CMC (0119) and FAusIMM (229036), an employee of NCL Ingenieria y Construcion SpA ("NCL") and an independent qualified person as such term is defined under NI 43-101. NCL is independent of the Company.

11 Ero Copper Corp

The pit designs and mine plan were optimized using the following economic and technical parameters: copper price of US$6,613 per tonne; average metallurgical recoveries of 91.3%; concentrate grade of 27% copper, copper concentrate logistics costs of US$108.20 per wmt; transport losses of 0.20%; copper concentrate treatment charges of US$59.50 per dmt, refining charges of U$0.0595 per pound of copper; copper payability of 96.3%; average mining cost of US$2.47 per tonne mined; processing costs of US$7.74 per tonne processed and G&A costs of US$3.83 per tonne processed; average pit slope angles that range from 30º for saproloite to 50º for fresh rock and a 2% CFEM government royalty.

Other modifying factors considered in the determination of the mineral reserve estimate include:

  • Overall slope angles of 30.0 degrees for saprolite, 42.0 degrees for weathered rock and 50.0 degrees for fresh rock;
  • Maximum bench height of 8.0 meters for saprolite and weathered rock and 16.0 meter doublebenches for fresh rock;
  • Double-traffic ramp design of 18.0 meters in width with 10% maximum gradient; and
  • Mining shapes of 6.0 meters by 10.0 meters with 4.0 meter flitch mining with consideration for orebody orientation.

The mineral reserve effective date is August 31, 2021.

NOTES

Non-IFRS measures

The Company uses certain non-IFRS measures, including C1 cash cost of copper produced (per lb) and EBITDA, which are not measures recognized under IFRS. The Company believes that these measures, together with measures determined in accordance with IFRS, provide investors with an improved ability to evaluate the underlying performance of the Company. Non-IFRS measures do not have any standardized meaning prescribed under IFRS, and therefore they may not be comparable to similar measures employed by other companies. The data is intended to provide additional information and should not be considered in isolation or as a substitute for measures of performance prepared in accordance with IFRS.

C1 cash cost of copper produced (per lb.)

C1 cash cost of copper produced (per lb) is the sum of production costs, net of capital expenditure development costs, divided by the copper pounds produced. C1 cash cost reported by the Company include treatment, refining charges, and offsite costs. C1 cash cost of copper produced per pound is a non-IFRS measure used by the Company to manage and evaluate operating performance of the Company’s operating mining unit and is widely reported in the mining industry as benchmarks for performance but does not have a standardized meaning and is disclosed in addition to IFRS measures.

12 Ero Copper Corp