Mexico

Buenavista Mine

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Categories

Overview

Mine TypeOpen Pit
Commodities
  • Copper
  • Molybdenum
  • Silver
  • Zinc
Mining Method
  • Truck & Shovel / Loader
Production Start1899
Mine Life2050
ShapshotThe Buenavista mining unit operates an open-pit porphyry copper mine, two concentrators and three SX-EW plants. The Buenavista del Cobre (“BVC”) deposit contains two pit areas, namely BVC and Buenavista Zinc (“BVZ”). The BVZ pit area lies within the largest BVC pit.

The Buenavista ore body is considered one of the world’s largest porphyry copper deposits.

Additionally, Southern Copper has built a new zinc concentrator plant, which will increase milling capacity and will allow us to recover zinc, along with copper contents. Ramping up of the plant began in the first quarter of 2024 after technical adjustments to the concentrator.

Owners

SourceSource
CompanyInterestOwnership
Grupo Mexico, S.A.B. de C.V. 88.87 % Indirect
Ownership Tree
Southern Copper Corporation (SCC) is an indirect subsidiary of Grupo Mexico S.A.B. de C.V. (Grupo Mexico) which, as of December 31, 2021, owns 88.9% of SCC through its wholly-owned subsidiary Americas Mining Corporation (AMC). SCC’s operations in Mexico are conducted through its subsidiary, Minera Mexico, S.A. de C.V. (Minera Mexico), which SCC acquired in 2005 from Americas Mining Corporation. SCC owns 99.6% of Minera Mexico.

Operadora de Minas e Instalaciones Mineras, S.A de C.V. (the “Buenavista unit”) operates Buenavista, an open-pit copper mine.

Contractors

ContractorContractDescriptionRef. DateSource
Mexico Generadora de Energia S. de R. L. Power supply Electrical power is supplied to the Buenavista site from the utility grid via 230 kilovolts (kV) overhead transmission lines. The bulk of the demand is supplied by Mexico Generadora de Energia S. de R. L. (MGE), a subsidiary of Grupo Mexico, the majority stockholder of Southern Copper. A minor portion of the site demand is supplied by Comision Federal de Electricidad (CFE), the state’s electrical power producer. Power is stepped down to 34.5-kV for distribution secondary substations. Feb 22, 2023

Deposit type

  • Porphyry
  • Vein / narrow vein
  • Breccia pipe / Stockwork

Summary:

The BVC deposit in the Cananea mining district is divided into two target zones, namely BVC and BVZ. The BVZ deposit conformably underlies the BVC deposit and is located to the northwest of the BVC deposit.

The BVC mine, formerly the Cananea Mine, is a porphyry Cu deposit, considered to be the largest in Mexico. Primary Cu mineralization in the Cananea mining district is centered around porphyry intrusions of quartz monzonite and some breccia chimneys. The main production centers at the district level are concentrated in brecciated bodies with high Cu grades. La Colorada Breccia hosts significant Cu, Au, and Ag mineralization.

Northwest of the BVC deposit is the BVZ deposit, a poly-metallic deposit containing mainly Zn, Cu, and Ag. Carbonate rocks of the Capote Basin and Puertecitos area show alteration and mineralization effects associated with multiple events of granitic intrusive rocks and quartz monzonitic porphyry. The skarn deposits at Puertecitos and the Elisa mine are related to favorable replacements in mantles.

Several types and styles of mineralization are present in the BVC deposit, including magmatic hydrothermal breccias (Cu-molybdenum [Mo]), skarn (Cu-zinc [Zn]), and sulfides (Cu-Mo).

The BVC deposit is underlain by the volcanic units of the Henrietta and Mesa Formations. The Henrietta Formation is widely distributed towards the western portion of the operational areas, while the volcanic sequences of the Mesa Formation extend to the east of the mining operation. These volcanic units are intruded by a series of porphyritic dykes that are located in the central and deep portion of the mining phases.

The predominant alteration in the main lithologies is phyllic alteration, characterized by the development of sericite, quartz, and pyrite. The Capote Quartzite only exhibits sericite between the quartz grains that constitute the rock. The alteration in the rocks of the Henrietta Formation is characterized by the presence of silica, sericite, pyrite, and chlorite as an alteration product of the ferromagnesian minerals. The volcanic rocks of the Mesa Formation have a higher proportion of sericite. The coarse-grained quartz-feldspar porphyry in the west slope expansion shows strong silicification. Volcanic rocks in the southeastern portion of the operation show moderate concentrations of sericite.

Diabase dykes with strikes N60°W to 80°W and N40°E, cut the volcanic and porphyry units in the area of the mine workings. Mineralized breccias in the BVC pit (Breccia 301), on the east slope of the Phase 8 development are the remnants of the La Colorada Breccia. All these breccia structures occur near the porphyry intrusion. Contact zones between porphyry and volcanic rocks throughout the district contain economic supergene and hypogene mineralization.

The BVZ deposit, is found within the Paleozoic sequence, comprising skarn-type mineralization hosted mainly in the Horquilla and Escabrosa formations. The skarn zone is delimited to the north by the Elisa Fault, with a west-northwest (WNW) orientation, and to the south by the Capote Pass Fault (Meinert, 1982), forming a monocline with a NW-SE direction and a dip of 40 to 60 to the NE. The skarn zone is also present in the Esperanza Formation.

Much of the Cu mineralization in the Cananea mining district is found in disseminated form and in veinlets in stockwork zones in the volcanic and intrusive rocks. Higher Cu grades are hosted in breccia structures, contact zones and some replacement bodies. Supergene enrichment constitutes important zones of Cu mineralization in the Cananea mining district, formed by chalcocite - covellite - digenite, generally replacing pre-existing primary minerals (pyrite - chalcopyrite). The distribution of mineralization in this zone is in disseminated form associated with volcanic rocks and porphyries of quartz-monzonite composition; in the replacement zone the occurrence of mineralization is in disseminated, nodular (patchy) form by cavity filling and replacement along the bedding planes. Below the supergene enrichment is primary mineralization consisting mainly of chalcopyrite with a small amount of bornite. The distribution of mineralization is predominantly in veinlets, in disseminated form occurring in very fine grains with abundant occurrence of chalcopyrite-based copper minerals. Above the supergene enrichment is a coating of goethite - hematite - jarosite.

A layer of hematite - goethite - jarosite oxides rests above the supergene enrichment between elevations 2,200 m to 1,800 m. The presence of native limonite in this layer suggests early enrichment cycles. The chalcocite-based supergene enrichment zone lies between elevations 1,800 m to 1,650 m amsl. The zone of supergene chalcocite and hypogene chalcopyrite mixed sulfides is between elevations 1,650 m to 1,400 m amsl. The occurrence of mineralization in the mixed zone is in two forms: disseminated and veinlets. As one goes deeper, disseminated mineralization decreases and veinlet mineralization increases. In this zone calcocite – chalcopyrite coexists.

Hypogenic primary chalcopyrite mineralization occurs below elevation 1,400 m and is known up to an elevation of 400 m amsl. In some unique geological structures (fault 8-125), it is common to observe the presence of iron oxides and supergene minerals at depths of more than 300 m from the current surface.

Reserves at December 31, 2023

Mineral reserves: The Copper mill Cu Cut-off grade was 0.30% (2023 – 2025), 0.25% (2026), 0.20% (2027) and 0.12% (2028+), the leach Cu equivalent Cut-off Grade at 0.06% Cu and the Zinc mill Cu equivalent Cut-off grade at 0.22%.

Cut-off grade: mineral resources are reported on break-even plant and leach profit basis. The estimate was constrained to the Resource pit based on a Cu price of $3.795/lb, Mo price of $11.50/lb and Zn price of $1.323/lb.
CategoryOre TypeTonnage CommodityGradeContained Metal
Probable ROM leach 1,033 Mt Copper 0.22 % 4,948 M lbs
Probable Sulphide 2,052 Mt Copper 0.41 % 18,670 M lbs
Probable Sulphide 2,052 Mt Molybdenum 319 M lbs
Probable Sulphide 2,052 Mt Zinc 2,852 M lbs
Indicated ROM leach 77 Mt Copper 0.13 % 196 M lbs
Indicated Sulphide 912 Mt Copper 0.36 % 7,226 M lbs
Indicated Sulphide 912 Mt Molybdenum 0.005 % 94 M lbs
Indicated Sulphide 912 Mt Zinc 0.18 % 3,598 M lbs
Inferred ROM leach 2,831 Mt Copper 0.14 % 8,518 M lbs
Inferred Sulphide 13,158 Mt Copper 0.2 % 57,978 M lbs
Inferred Sulphide 13,158 Mt Molybdenum 0.004 % 1,087 M lbs
Inferred Sulphide 13,158 Mt Zinc 0.033 % 9,727 M lbs

Mining Methods

  • Truck & Shovel / Loader

Summary:

The Buenavista del Cobre (“BVC”) deposit is divided into two pit areas, namely BVC and Buenavista Zinc. The BVZ pit area lies within the largest BVC pit.

Buenavista iscurrently applying conventional open-pit mining methods to extract copper ore for further processing in the concentrator.

A life-of-mine (LOM) plan and pit design were developed for 2023 through 2050. LOM plan pit design is based on current geotechnical and hydrology designs, and extraction limits, which are dictated by mining recovery and dilution factors, cut-off grade (COG) estimation, and economic pit optimization analysis. Pit design includes detailed design factors for wall slopes, berm widths, pit bottom, and access ramp grades and widths.

The LOM plan includes annual forecasts of waste removal and transportation and ore extraction and beneficiation. Waste is hauled to one of the 2 ex-pit waste dumps, or overburden storage facilities (OSFs).

Overburden material is loaded by 15 electric rope shovels loading 360-t haul trucks. Dozers assist the loading fleet with general clean-up and material removal, as necessary. Dozers are used to push overburden down the sides of the OSFs on an as-needed basis.

The following recommendations were made for the Buenavista mine: inter-ramp slope design angles for the 15-year pit plan forall of the 21 design sectors defined on a rock-fabric-based catch bench analysis, using double bench, can range from 48° and 55°,and the inter-ramp slope angles are based on geometries obtained from the back-break analysis using 80% reliability of achievingthe required 7.6 meter catch bench width for a single bench configuration and 10.6 meter catch bench width for a double benchconfiguration. Preliminary observations suggest the 15-year pit walls may be relatively free-draining; the back-break analysisassumed depressurized conditions of mine benches, and the inter-ramp stability analysis were performed for both saturated anddepressurized conditions.

Comminution

Crushers and Mills

TypeModelSizePowerQuantity
Gyratory crusher 1
Ball mill 6

Summary:

- Size reduction of the ore by a primary gyratory crusher to reduce the ore size from ROM to minus 200 mm;
- Stockpiling primary crushed ore and then reclaiming by feeders and conveyor belts;
- Size reduction of the ore by secondary and tertiary crushing to reduce the ore size from 200 millimeters to 80 percent minus 8-9 mm;
- Crushed ore conveyed to the fine ore stockpile building;
- Fine crushed ore reclaimed and conveyed to the grinding circuit;
- Grinding ore in a conventional ball mill circuit prior to processing in a flotation circuit. The ball mills will operate in closed circuit with hydro-cyclones to deliver an ore size of 80 percent passing 105 microns to the flotation circuit.

Processing

  • Sulfuric acid (reagent)
  • Crush & Screen plant
  • Flotation
  • ROM/dump leach
  • Dewatering
  • Solvent Extraction & Electrowinning

Summary:

Ore is mined, transported, and crushed for processing to recover copper concentrate, molybdenum concentrate, and zinc concentrate. Two copper beneficiation plants, Concentrator 1 and Concentrator 2, are in operation at BVC.

Concentrator
Concentrator 1 has been in operation since 1988 and Concentrator 2 since 2016. The two concentrators follow a conventional process of crushing, screening, ball milling and sequential flotation to separate copper and molybdenum concentrates. The differences between the two plants are size of the equipment and the number of machines dedicated to each unit operation, because Concentrator 2 was designed and built with modern equipment 30 years after Concentrator 1.

Buenavista uses state-of-the-art computer monitoring systems at the concentrators, the crushing plant and the flotation circuit in order to coordinate inflows and optimize operations. In the original concentrator, material with a copper grade above a cut-off grade of approximately 0.30% is currently loaded onto trucks and sent to the milling circuit, where giant rotating crushers reduce the size of the ore to approximately one-half of an inch. The ore is then sent to the ball mills, which grind it to the consistency of fine powder. The finely ground powder is agitated in a water and reagents solution and is then transported to flotation cells. Air is pumped into the cells producing a froth, which carries the copper mineral to the surface but not the waste rock, or tailings. Recovered copper, with the consistency of froth, is filtered and dried to produce copper concentrates with an average copper content of approximately 24%. Concentrates are then shipped by rail to the smelter at La Caridad.

In the second concentrator, material with a copper grade above a cut-off grade of approximately 0.30% is sent to a three-phase milling circuit, where the ore size is reduced to approximately one-half inch. The ore is then sent to a circuit of six ball mills, which grind it to the consistency of fine powder. The finely ground powder is agitated in a water and reagents solution and is then transported to flotation cells. Air is pumped into the cells producing a froth, which carries the copper mineral to the surface but not the waste rock, or tailings. Recovered copper, with the consistency of froth, is filtered and dried to produce copper concentrates with an average copper content of approximately 24%. Concentrates are then sent by trucks or by railroad to the LaCaridad smelter or to the Guaymas port, at Sonora, for export.

SX-EW Plant
The Buenavista unit operates a leaching facility and three SX-EW plants. All copper ore with a grade lower than the mill cut-off grade of 0.30%, but higher than 0.15%, is delivered to the leach dumps. A cycle of leaching and resting occurs for approximately five years in the run-of-mine dumps and three years for the crushed leach material. A review of the cut-off grades based on economics is recommended to be reassessed as described above.

The L-SX-EW process encompasses leaching, solvent extraction, and electrowinning for the production of pure copper cathode. Copper is recovered as a solution of copper sulfate from low-grade ore by irrigating the ore with acidic leach solutions returning from the SX plants.

The leach solutions are loaded with copper as they percolate through the ore heaps and become pregnant leach solutions (PLS) that are fed to the SX-EW plants. The PLS from all the areas is pumped to two central PLS surge ponds, from where the PLS is fed to the solvent extraction (SX) plants.

In the SX plants the PLS is mixed with an organic solution, a mixture of a reagent diluted with kerosene, that extracts the copper from the PLS and releases acid. The organic solution loaded with copper (LO) then passes to the stripping section where it is mixed with a highly acidic solution, called spent or lean electrolyte (SE). The high acid content of the SE causes the LO to release copper to the SE and pick-up acid, regenerating the reagent molecules and the SE becomes Rich Electrolyte (RE) to feed the Electrowinning plant (EW).

In EW, the RE from SX is recirculated through electrowinning cells with multiple stainless-steel cathodes and lead anodes. A direct electrical current is applied to the cells that causes the copper in the RE to be deposited in the cathodes and the RE becomes SE that returns to SX to strip more copper from the LO.

As part of the expansion program for this unit, in 2013 the Company completed the construction of the first molybdenum plant with an annual production capacity of 2,000 tonnes of molybdenum contained in concentrate. The plant was designed to process 1,500 tonnes of copper-molybdenum concentrates per day with a content recovery of approximately 80% copper and 50%molybdenum. The molybdenum plant consists of thickeners, homogenizer tanks, flotation cells, column cells and a holo-flite dryer. The second molybdenum plant was designed to process 3,040 tonnes of copper-molybdenum concentrates per day for a content recovery between 80% and 87% for copper and 60% for molybdenum. The plant generated its first production lot in July 2016 and fully initiated operations in November 2016.

Buenavista Zinc - Sonora: This project is located within the Buenavista deposit, where the Company has built a new concentrator plant. This facility has a production capacity of 100,000 tonnes of zinc and 20,000 tonnes of copper per year. When operating, the concentrator will double the Company’s zinc production capacity and will provide more than 2,000 jobs on the operating front.

Project update: the capital budget for the project is $439 million, most of which has already been invested. Progress is 99%; the Company has initiated the commissioning process. The ramping up of the plant began in the first quarter of 2024 after technical adjustments to the concentrator. The company expects to produce 54,500 tonnes of zinc and 11,900 tonnes of copper in 2024 and an average of 90,200 tonnes of zinc and 20,700 of copper per year in the next five years.

Recoveries & Grades:

CommodityParameter202320222021202020192018201720162015
Copper Concentrate Grade, % 22.622.923.323.923.823.723.423.823
Molybdenum Recovery Rate, % 70.870.56967.365.658.439.925.125.6
Molybdenum Head Grade, % 0.0110.010.010.0110.0130.0120.0130.0130.013
Molybdenum Concentrate Grade, % 51.651.251.252.451.851.151.449.550.3
Copper Recovery Rate, % 70.847.8

Production

Since 2019 stripping ratio obtained dividing waste by leachable material plus ore mined.
CommodityProductUnits202320222021202020192018201720162015
Copper Cathode kt 8893829810089112131122
Copper Metal in concentrate kt 329339341334338325319316162
Copper Concentrate kt 1,4561,4821,4651,3981,4201,3711,3621,330705
Molybdenum Metal in concentrate kt 5.45.45.25.56.18.43.51.60.9
Molybdenum Concentrate kt 10101010129.66.73.21.9
Silver Metal in concentrate koz 4,6695,2084,7745,5505,7555,1624,9884,8192,367

Operational metrics

Metrics202320222021202020192018201720162015
Daily processing capacity 197,000 t of ore (in concentrator)197,000 t of ore (in concentrator)197,000 t of ore (in concentrator)182,000 t of ore (in concentrator)182,000 t of ore (in concentrator)176,700 t of ore (in concentrator)
Annual production capacity 174,470 t of copper cathode174,470 t of copper cathode174,470 t of copper cathode174,470 t of copper cathode174,470 t of copper cathode174,470 t of copper cathode
Stripping / waste ratio 0.66 0.72 0.52 0.29 0.37 3.23 3.14 2.88 6.23
Ore tonnes mined 194,020 kt196,810 kt213,304 kt201,013 kt211,419 kt215,717 kt227,575 kt190,066 kt184,272 kt
Total tonnes mined 322,142 kt337,727 kt324,860 kt259,860 kt288,882 kt297,718 kt288,716 kt257,395 kt282,954 kt
Tonnes processed 72,609 kt of ore (in concentrator)74,121 kt of ore (in concentrator)74,302 kt of ore (in concentrator)73,011 kt of ore (in concentrator)70,371 kt of ore (in concentrator)70,328 kt of ore (in concentrator)

Production Costs

Commodity production costs have not been reported.

Financials

Units2023202220212020201920182017
Book Value M USD 3,228  3,070  3,260  3,304   3,298   3,431   3,592  

Heavy Mobile Equipment

Ref. Date: February 24, 2022

SourceSource
HME TypeModelSize
Shovel (rope) P&H 2800XPA 28 m3
Shovel (rope) P&H 4100 XPC 57 m3
Truck (haul) Caterpillar 797F 360 t
Truck (haul) Komatsu 830E 210 t
Truck (haul) Komatsu 930E 275 t
Truck (haul) Komatsu 960E 327 t
Truck (haul) Bucyrus-Erie 210 t

Personnel

Mine Management

Job TitleNameProfileRef. Date
Chief Engineer Jorge Vazquez LinkedIn May 20, 2024
Consultant - Mining & Costs Danny Tolmer LinkedIn Feb 24, 2022
Maintenance General Manager Jose Arturo Sagaon Duran LinkedIn May 20, 2024
Maintenance Superintendent Alejandro Marquez LinkedIn May 20, 2024
Maintenance Superintendent David García LinkedIn May 20, 2024
Mine Manager Christian Torrecillas LinkedIn May 20, 2024

EmployeesYear
833 2014

Aerial view:

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