Geology

The La Caridad deposit is a typical porphyry copper and molybdenum deposit as seen also in the southwestern basin of United States. The La Caridad mine uses a conventional open-pit mining method. The ore body is at the top of a mountain, which gives La Caridad the advantage of a relative low waste-stripping ratio, natural pit drainage and relative short haul for both ore and waste. The mining method involves drilling, blasting, loading and haulage of ore mill and waste to the primary crushers and the leach materials and waste to dumps, respectively.

La Caridad deposit is located in northeastern Sonora, Mexico. The deposit is situated near the crest of the Sierra Juriquipa, about 23 kilometers southeast of the town of Nacozari, Sonora, Mexico. The Sierra Juriquipa rises to elevations of around 2,000 meters in the vicinity of La Caridad and is one of the many north-trending mountain ranges in Sonora that form a southern extension of the basin and range province.

The La Caridad porphyry copper-molybdenum deposit occurs exclusively in felsic to intermediate intrusive igneous rocks and associated breccias. Host rocks include diorite and granodiorite. These rocks are intruded by a quartz monzonite porphyry stock and by numerous breccia masses, which contain fragments of all the older rock types.

Supergene enrichment, consisting of completes to partial chalcosite (Cu2S) replacement of chalcopyrite (CuFeS2). The zone of supergene enrichment occurs as a flat and tabular blanket with an average diameter of 1,700 meters and thickness generally between 0 and 90 meters.

Economic ore is found as disseminated sulfurs within the central part of the deposit. Sulfide-filled breccias cavities are most abundant in the intrusive breccia. This breccia-cavity mineralization occurs as sulfide aggregates which have crystallized in the spaces separating breccia clasts. Near the margins of the deposit, mineralization occurs almost exclusively in veinlets. Ore minerals include chalcopyrite (CuFeS2), chalcosite (Cu2S) and molybdenite (MoS2).

Mine Exploration

The La Caridad ore body has been mined for over 30 years. The extent of the model area is approximately 6,000 meters by 4,000 meters with elevation ranging from 750 to 1,800 meters.

Sixteen drilling campaigns have been conducted on the property since 1968. These campaigns drilled a total of 3,317 drill holes: 1,154 were diamond drill holes and 2,163 were reverse circulation. We have also drilled some hammer and percussion drill holes. A total of 634,080 meters have been drilled through December 2011.

In 2008, La Caridad finished a large exploration program of 50,000 meters. The target was to reach to the 900 level in order to reduce the drilling space and to define the copper and molybdenum mineralization continuity and also carry out metallurgical testing for the flotation and leaching processes. There was no exploration program between 2009 and 2011. In 2012, we will be developing an exploration program of 10,000 meters with the objective of further defining the copper and molybdenum mineralization continuity.

Concentrator

La Caridad uses state-of-the-art computer monitoring systems at the concentrator, the crushing plant and the flotation circuit in order to coordinate inflows and optimize operations. The concentrator has a current capacity of 90,000 tons of ore per day.

Ore extracted from the mine with a copper grade over 0.30% is sent to the concentrator and is processed into copper concentrates and molybdenum concentrates. The copper concentrates are sent to the smelter and the molybdenum concentrate is exported. The molybdenum recovery plant has a capacity of 2,000 tons per day of copper-molybdenum concentrates. The lime plant has a capacity of 340 tons of finished product per day.

La Caridad concentrator plant consists of two primary crushers, six secondary crushers, twelve tertiary crushers, twelve ball mills, a master milling control system, 100 primary flotation cells, four re-grinding mills, 96 cleaning flotation cells, twelve thickeners and six drum filters.

SX/EW Plant

Approximately 637.4 million tons of leaching ore with an average grade of approximately 0.235% copper have been extracted from the La Caridad open-pit mine and deposited in leaching dumps from May 1995 to December 31, 2011. All copper ore with a grade lower than the mill cut-off grade 0.30%, but higher than 0.15% copper, is delivered to the leaching dumps. In 1995, we completed the construction of a SXEW facility at La Caridad that has allowed processing of this ore and certain leach ore reserves that were not mined and has resulted in a reduction in our copper production costs. The SXEW facility has an annual capacity of 21,900 tons of copper cathodes.

The La Caridad SX-EW plant has nine irrigation systems for the dumps, two PLS dams and a container of heads that permits the combination of the solutions of both dams and which feeds the SXEW plant with a more homogenous concentration. The plant has three trains of solvent extraction with a nominal capacity of 2,070 cubic meters per hour and 94 electrowinning cells distributed in one single electrolytic bay. The plant has a daily production capacity of 62 tons of copper cathodes with 99.999% purity.

Smelter

Copper concentrates from Buenavista, Santa Barbara, Charcas and La Caridad are transported by rail and truck, respectively, to the La Caridad smelter where they are processed and cast into copper anodes of 99.2% purity. Sulfur dioxide off gases collected from the flash furnace, the El Teniente converter and conventional converters are processed into sulfuric acid, at two sulfuric acid plants. Approximately 2% to 3% of this acid is used by our SXEW plants and the balance is sold to third parties.

Almost all of the anodes produced in the smelter are sent to the La Caridad copper refinery. The actual installed capacity of the smelter is 1,000,000 tons per year, a capacity that is sufficient to treat all the concentrates of La Caridad and Buenavista, and starting in 2010, the concentrates from the IMMSA mines, as we closed the San Luis Potosi smelter. The smelter includes a flash type concentrates drier, a steam drier, a flash furnace, one El Teniente modified converter furnace, two electric slag-cleaning furnaces, three Pierce-Smith converters, three rafinnate furnaces and two casting wheels. The anode production capacity is 300,000 tons per year.

Refinery

La Caridad includes an electrolytic copper refinery that uses permanent cathode technology. The installed capacity of the refinery is 300,000 tons per year. The refinery consists of an anode plant with a preparation area, an electrolytic plant with an electrolytic cell house with 1,115 cells and 32 liberator cells, two cathode stripping machines, an anode washing machine, a slime treatment plant and a number of ancillary installations. The refinery is producing grade A copper cathode of 99.99% purity. Anodic slimes are recovered from the refining process and sent to the slimes treatment plant where additional copper is extracted. The slimes are then filtered, packed and shipped to the La Caridad precious metals refinery to produce silver and gold.

The operations of the precious metal refinery are divided into two stages: (i) the antimony is eliminated from the slime, and (ii) the slime is dried in a steam dryer. After this the dried slime is smelted and a gold and silver alloy is obtained, which is known as dore. The precious metal refinery plant has a hydrometallurgical stage and a pyrometallurgical stage, besides a steam dryer, dore casting system, Kaldo furnace, 20 electrolytic cells in the silver refinery, one induction furnace for fine silver, one silver ingot casting system and two reactors for obtaining fine gold. The process ends with the refining of the gold and silver alloy.

Copper Road Plant

A rod plant at the La Caridad complex was completed in 1998 and reached its full annual operating capacity of 150,000 tons in 1999. The plant is producing eight millimeter copper rods with a purity of 99.99%. The rod plant includes a vertical furnace, one retention furnace, one molding machine, one laminating machine, one coiling machine and one coil compacter.

Other facilities include a lime plant with a capacity of 132,000 tons per year; two sulfuric acid plants, one with a capacity of 2,625 tons per day and the second with a capacity of 2,135 tons per day; three oxygen plants, each with a production capacity of 275 tons per day; and two power turbo generators, one of them uses residual heat from the flash furnace, the first with a 11.5 megawatt capacity and the second with a 25 megawatt capacity.

Geology

The Buenavista mining district lies on the southern cordilleran orogen, which extends from southern Mexico to northwestern United States. It also falls within the Basin and Range metallogenic province. Geological and structural features in the district are representative of large, disseminated type, porphyry copper deposits. A calcareous sedimentary sequence of lower Paleozoic age, litho logically correlated with a similar section in southeastern Arizona, uncomformably overlies Precambrian granite basement. The entire section was covered by volcanic rocks of Mesozoic age and later intruded by deep seated granodiorite batholiths of Tertiary age, with further quartz monzonite porphyry differentiates of Laramide age.

Mineralization in the district is extensive covering a surface area of approximately 30 square kilometers. An early pegmatitic stage associated with bornite-chalcopyrite-molybdenite assemblage was followed by a widespread flooding of hydrothermal solutions with quartz- pyrite-chalcopyrite. A pervasive quartz-sericite alteration is evident throughout the district’s igneous rock fabric.

An extensive and economically important zone of supergene enrichment, with disseminated and stockworks of chalcocite (Cu2S), developed below the iron oxide capping. This zone coincides with the topography and has an average thickness of 300 meters. A mixed zone of secondary and primary sulfides underlay the chalcocite blanket. The hypogene mineralization, principally chalcopyrite, (CuFeS2), extensively underlies the orebody. Molybdenite occurs throughout the deposit and the content tends to increase with depth.

The Buenavista copper porphyry is considered world-class and unique. The deepest exploration results in the core of the deposit have confirmed significant increase in copper grades. Similar porphyry copper deposits usually contain lower grades at depth. The district is also unique for the occurrence of high-grade breccia pipes, occurring in clusters following the trend of the district.

Current dimensions of the mineralized ore body are 5x3 kilometers, and projects to more than 1 kilometer at depth. Considering the geological and economic potential of the Buenavista porphyry copper deposit, it is expected that the operation can support a sizeable increase in copper production capacity.

Mine Exploration

Due to Buenavista’s illegal work stoppage, there were no exploration programs developed in 2010 and 2009. In 2011, we resumed exploration activities. In-fill core drilling was conducted at the Buenavista zinc-copper-silver deposit, including directional drilling for geotechnical purpose. A deep drilling campaign was initiated to explore the extent of the deposit at depth. Likewise, a condemnation drilling program was initiated to define areas for future infrastructure as well as areas where leach and waste dumps will be deposited. A total of 28,369 meters of core drilling was completed. A geohydrology program was initiated to explore the possibility of groundwater sources within the mine limits. A total of 756 meters was drilled with a down-the-hammer ring in four holes. The reverse circulation in-fill drilling campaign for short term mine planning totaled 4,737 meters during 2011.

Concentrator

Buenavista uses state-of-the-art computer monitoring systems at the concentrator, the crushing plant and the flotation circuit in order to coordinate inflows and optimize operations. Material with a copper grade over 0.38% is 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 and bar 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 28%. Concentrates are then shipped by rail to the smelter at La Caridad.

The Buenavista concentrator plant, with a milling capacity of 76,700 tons per day, consists of two primary crushers, four secondary crushers, ten tertiary crushers, ten primary mills, one expert control system, five mills for re-grinding, 103 primary flotation cells, ten column cells, seventy exhaustion flotation cells, seven thickeners and three ceramic filters. In addition, the facility has 48 wells and a pumping station for fresh water supply, a tailings dam and a reclaimed water pumping station.

SX/EW Plant

The Buenavista unit operates a leaching facility and two SXEW plants. All copper ore with a grade lower than the mill cut-off grade of 0.38%, but higher than 0.25% copper, is delivered to the leach dumps. A cycle of leaching and resting occurs for approximately five years to achieve a 62.5% recovery in the run-of-mine dumps and three years for the crushed leach material to achieve a 73% recovery.

The Buenavista unit currently maintains 21.8 million cubic meters of pregnant leach solution in inventory with a concentration of approximately 1.95 grams of copper per liter.

Major equipment at the number I and II SXEW plants includes two crushing systems (No.1 and No.2). Crushing system No. 1 has a capacity of 32,000 tons per day and includes an apron feeder, a conveyor belt feeder, eight conveyor belt systems and a distributing bar. Crushing system No. 2 has a capacity of 48,000 tons per day and includes one crusher, a conveyor belt feeder, four conveyor belts and a distributing bar. There are three irrigation systems for the dumps and eleven dams for the pregnant leach solution (PLS). Plant I has four solvent extraction tanks with a nominal capacity of 16,000 liters per minute of PLS and 52 electro winning cells and has a daily production capacity of 30 tons of copper cathodes with 99.999% purity. Plant II has five trains of solvent extraction with a nominal capacity of 55,000 liters per minute of PLS and 216 cells distributed in two bays and has a daily production capacity of 120 tons of copper cathodes with 99.9% purity.

As mentioned above we intend to increase the Buenavista unit’s production of copper cathodes with a new SXEW plant, (SXEW III) with an annual capacity of 120,000 tons. The plant would produce copper cathodes of ASTM grade 1 or LME grade A. Please see Item 7 - “Capital Investment Program” for further information.

Geology

The Taxco district is stratigraphically formed of rocks from Jurassic to recent periods, which are described below, with emphasis on the mineralization control characteristics. The Taxco schist is composed of a series of schists and fylites, most likely from a volcanicsedimentary sequence of tufa and limonites. They represent a sequence of metamorphological arch and its age has been defined as Jurassic Medium. The Morelos formation from the Upper Cretaceous age (Apian-Turonian) lies on a discordant form over Taxco schist and its contact is several times marked by a clay zone (mylonites) and breccia, which implies a shifting of this unit over the schist (packs). The Mezcala formation is constituted by a sequence of shale and sandstone with some inter-stratified layers of limestone. Its base is calcarean. Its top tends to be rich in clay with thin limestone layers. The Balsas group is constituted by conglomerates and is sandy on its base, rests in discordance form on an erosioned surface from the Mexcala formation. The Tilzapotla Ryolite is the newest rock, which emerged in the district before the alluvial deposit. It is formed of flux, breccia, tuffaceous, ignimbrites and vitrophyrre of ryolite composition.

There are four types of ore deposits found in Taxco district. In order of importance they are as follows: fissure-filling veins, replacement veins, blanket-like replacement bodies (so called “mantos”), stock works and brecciate chimneys. The three first ones are intimately related and they were formed in the same era, although in different stages.

The veins reach up to two kilometers in length with a variable potency of thirty centimeters up to eight meters, which is the case of copper veins at the mines of Guerrero, Hueyapa and Palo Amarillo at the San Antonio mine; the Remedios mine has among other veins, El Muerto and El Cristo one kilometer long and five meters in average potency.

Economic ore is found in the deposit in veins. Ore mineral include argentiferous galena (PbS), sphalerite (ZnS), pyrargyrite (Ag3SbS3), and other sulfosalts, and replacement “mantos.” The most mineralized zones are in the vicinity of the veins with the limestone. The mineralization is more intensive in the base of the limestone and consists of sphalerite (ZnS), galena (PbS), pyrite (FeS) and magnetite (FeOFe2O3).

Mine Exploration

There was no mine exploration drilling in three years ending December 31, 2012 at the Taxco mine.

There was no production at the Taxco mine in the three years ending December 31, 2012.  

Geology

The majority of production from the district comes from quartz veins within faults and fractures. The north to northwestern trending veins is up to several kilometers long, dips steeply to the west and is 0.5 to 30 meters wide. Ore shoots up to several hundred meters in length, extends to at least 900 meters below the surface and is separated from other ore by 0.5 to 1 meter of barren quartz vein. Metal zoning occurs in some veins, with zinc and lead content generally decreasing with depth and copper increasing with depth. Three main systems of veins exist inside the district, represented by the veins Coyote, Segovedad Novedad and Coyote Seca Palmar. In addition to the main veins, there are many smaller sub-parallels to branching ore bearing veins. Economic ore minerals include sphalerite (ZnS), marmatite (ZnFeS), galena (PbS), chalcopyrite (CuFeS2) and tetrahedrite (CuFe12 Sb4S13). Gangue minerals include quartz (SiO2), pyrite (FeS2), magnetite (Fe2O4), pirrotite (Fe2+S), arsenopyrite (FeAsS) and fluorite (CaF2).

The Santa Barbara district has mineralization to indicate that it will continue to be a significant producer of lead, copper and zinc for decades. The full potential of the district has not yet been defined, but the area seems to justify an increase in exploration.

Mine Exploration

At Santa Barbara, 13,074 meters were drilled from underground stations and 50,867 meters from the surface in 2012. With this drilling 6,964,423 tons were added to the reserve base in 2012. For 2013, 47,000 meters of surface diamond drilling are planned.

Geology

San Martin lies in the Central Mesa between two major geologic provinces, Sierra Madre Occidental and Sierra Madre Oriental. The main sedimentary rock-formation in the San Martin district is the Upper Cretaceous Age Cuesta del Cura limestone. The formation is an interlayered sequence of shallow marine limestone and black chert, and it is overlain by Indura formation which outcrops at the foot of the topographic heights of the Cuesta del Cura formation. It consists mainly of alternating shales and fine-grained clayed limestones in ten to thirty centimeter thick layers.

The district’s most important mineral deposits are replacement veins and bodies generated in the skarn by Cerro de la Gloria granodiorite intrusion. An extensive zone of skarn west of the intrusive hosts, the San Marcial, Ibarra and Gallo-Gallina main ore veins, which appear at the surface for distances of up to 1,000 meters, with thicknesses of 40 centimeters to four meters, paralleling the intrusive contact. In the central part of the deposit there is a horizontal zoning with respect to the contact of the intrusive with high values of silver and copper. In the top of the deposit there is mostly lead and zinc. In the northeast/east over concentric structures to the intrusive there is an increment of lead, zinc and silver in the skarn. Economic ore is found as replacement ore bodies between the main veins as massive and disseminated sulfides with widths from eight meters up to 200 meters. These bodies consist mostly of chalcopyrite (CuFeS2), sphalerite (ZnS), galena (PbS), bornite (Cu5FeS4), tetrahedrite (CuFe12Sb4S13), native silver (Ag), pyrrite (FeS), arsenopyrite (FeAsS) and stibnite (Sb2S3). Molybdenum and tungsten are found in little portions in the skarn near the contact associated with the calcite.

Mine Exploration

There was no mine exploration drilling in the three years ending December 31, 2012 because the San Martin mine was on strike. There was no production at the San Martin mine in the three years ending December 31, 2012.

Geology

The Charcas mining district occupies the east-central part of the Mexican Central Mesa and is part of the Sierra Madre metallogenic province. Geological history starts in the Superior Triasic, where sandy clay sediments were deposited argilloarenaceous. Due to emersion in the beginning of the Jurassic Superior, the sediments suffered intense erosion, settling on continental sediments. This sequence was affected by tectonic effort, which folded and failed on this rock package. Later the positioning of intrusive rocks originated fractures, which gave way to positioning of mineral deposits. The site’s paragenesis suggests two stages of mineralization. First minerals are rich in silver, lead and zinc, with abundant calcite and small quantities of quartz chalcopyrite. Second, there is a link of copper and silver, where the characteristic minerals are chalcopyrite, lead ore with silver content, pyrite and scarce sphalerite. Economic ore is found as replacement sulfurs in carbonates host rock. The ore mineralogy is comprised predominantly of chalcopyrite (CuFeS2), sphalerite (ZnS), galena (PbS) and silver minerals as diaphorite (Pb2Ag3Sb3S8).

Mine Exploration

In 2012, at Charcas, 19,068 meters of diamond drilling were executed from underground stations and 26,979 meters from the surface. With this drilling, 1,452,895 tons were added to the reserve base in 2012. Additional drilling surface program of 30,000 meters is planned in 2013.

Geology

Santa Eulalia is the largest of a number of similar districts that lie along the intersection of the Laramide aged Mexican Thrust Belt and the Tertiary volcanic plateau of the Sierra Madre Occidental. Deposits throughout the belt occur in a thick Jurassic-Cretaceous carbonate succession that overlies Paleozoic or older crust.

The main sedimentary rock in the Santa Eulalia district is the Lower Cretaceous Limestone. These are irregularly covered by volcanic sedimentary conglomerates that are overlaid by volcanic rocks of the tertiary and alluvial material of the Quaternary Age. In the Santa Eulalia mining district a thickness of 500 meters of sedimentary rocks is known to exist which consists of the following formations: 1) Formation Lagrima (limestone fossils); 2) Formation Glen Rose (limestone blue and at its base a black limestone appears); and 3) Formation Cuchillo (limestone with shale). Dikes and sills of riolite composition and sills of diabase also exist.

In the district there are several systems of fractures and faults associated with the emplacement of felsitic and maphic intrusives. The most important controller of the ore bodies are the north-south fractures.

The mineralization corresponds in its majority to ore skarns — silicoaluminates of calcium, iron and manganese with variable quantities of lead, zinc, copper and iron sulfides, located in the planes of crossings in the interstices of the silicates. Economic ore is found as replacement in the Limestone Glen Rose in the contact with dikes and sills and replacements in diabase sills. The mineralogy is comprised predominantly of sphalerite (ZnS), galena (PbS) and small quantities of pyrargyrite (Ag3SbS3).

Mine Exploration

At Santa Eulalia, in 2012, 4,695 meters were drilled from underground stations and 14,467 meters from the surface. With this drilling, 170,000 tons were added to the reserve base in 2012. In 2013, an additional diamond drilling program of 18,000 meters is planned.

Zinc Refinery

The San Luis Potosi electrolytic zinc refinery was built in 1982. It was designed to produce 105,000 tons of refined zinc per year by treating up to 200,000 tons of zinc concentrate from our own mines, principally Charcas, which is located 113 kilometers from the refinery. The refinery produces special high grade zinc (99.995% zinc), high grade zinc (over 99.9% zinc) and zinc-based alloys with aluminum, lead, copper or magnesium in varying quantities and sizes depending on market demand. Refined silver and gold production is obtained from tolling services provided by Industrias Penoles, a Mexican mining company.

The electrolytic zinc refinery’s major equipment includes a roaster with 85 square meters of roasting area, a steam recovery boiler and an acid plant. There is a calcine processing area with five leaching stages: neutral, hot acid, intermediate acid, acid, purified fourth and jarosite, as well as two stages for solution purifying. Additionally, the equipment includes a cell house with two electrowinning circuits to finally obtain metallic zinc; an alloy and molding area with two induction furnaces and four molding systems, two of them with chains to produce 25 kilogram ingots; and two casting wheels to manufacture one ton jumbo pieces.

Geology

The Toquepala porphyry copper deposit is located on the western slopes of Cordillera Occidental, in the southern-most Andes Mountains of Peru. The deposit is part of a mineral district that contains two additional known deposits, Cuajone and Quellaveco.

The Toquepala deposit is in the southern region of Peru, located on the western slope of the Andes mountain range, approximately 120 kilometers from the border with Chile. This region extends into Chile and is home to many of the world’s most significant known copper deposits. The deposit is in a territory with intrusive and eruptive activities of rhyolitic and andesitic rocks which are 70 million years old (Cretaceous-Tertiary) and which created a series of volcanic lava. The lava is composed of rhiolites, andesites and volcanic agglomerates with a western dip and at an altitude of 1,500 meters. These series are known as the Toquepala Group. Subsequently, different intrusive activities occurred which broke and smelted the rocks of the Toquepala Group. These intrusive activities resulted in diorites, granodiorites and dikes of porphyric dacite. Toquepala has a simple mineralogy with regular copper grade distribution. Economic ore is found as disseminated sulfurs throughout the deposit as veinlets, replenishing empty places or as small aggregates. Ore minerals include chalcopyrite (CuFeS2), chalcosine (Cu2S) and molybdenite (MoS2). A secondary enrichment zone is also found with thicknesses between 0 and 150 meters.

Mine Exploration

Exploration activities during the drill campaign in 2012 are as follows:

Concentrator

Our Toquepala concentrator operations use state-of-the-art computer monitoring systems in order to coordinate inflows and optimize operations. Material with a copper grade over 0.40% is loaded onto rail cars and sent to the crushing circuit, where rotating crushers reduce the size of the rocks by approximately 85%, to less than one-half of an inch. The ore is then sent to the rod and ball mills, which grind it in a mix with water to the consistency of fine powder. The finely ground powder mixed with water 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. The bulk concentrate with sufficient molybdenum content is processed to recover molybdenum by inverse flotation. This final copper concentrate with a content of approximately 26.5% of copper is filtered in order to reduce moisture to 8.5% or less. Concentrates are then shipped by rail to the smelter at Ilo.

Tailings are sent to thickeners where water is recovered. The remaining tailings are sent to the Quebrada Honda dam, our principal tailings storage facility.

Major concentrator plant equipment at Toquepala includes one primary crusher, three secondary crushers, six tertiary crushers, eight rod mills, twenty-four ball mills, one distributed control system (DCS), one expert grinding system, forty-two collective flotation cells, fifteen column cells, seventy-two agitair 1.13 cubic meter cells, two larox pressure filters, five middling thickeners, two conventional tailings thickeners, three high-rate tailings thickeners, one tripper car, one track tractor, and one recycled water pipe line. The expected useful life of the principal equipment is over 20 years due to our equipment maintenance programs.

SX/EW Plant

The SXEW facility at Toquepala produces grade A LME electrowon copper cathodes of 99.999% purity from solutions obtained by leaching low-grade ore stored at the Toquepala and Cuajone mines. The leach plant commenced operations in 1995 with a design capacity of 35,629 tons per year of copper cathodes. In 1999 the capacity was expanded to 56,000 tons per year.

Copper oxides from Cuajone with a copper grade higher than 0.218%, with an acid solubility index higher than 46% and a cyanide solubility index higher than 16% are leached. In Toquepala, the leach material cutoff grade is 0.095% and therefore material with a total copper grade between 0.095% and 0.40% are leached.

Major equipment at the Cuajone crusher plant includes one primary jaw crusher and one secondary cone crusher with a capacity of 390 tons per hour. In addition, the plant has one agglomeration mill, one front end loader and two 445E dresser trucks of 120-ton capacity, and one 830E Komatsu of 240-ton capacity truck for hauling to the leach dumps. Copper in solution produced in Cuajone is sent to Toquepala through an eight-inch pipe laid alongside the Cuajone-Toquepala railroad track.

Major equipment at the Toquepala plant includes five pregnant solution (PLS) ponds, each with its own pumping system to send the solution to the SXEW plant. The plant also has three lines of SX, each with a nominal capacity of 1,068 cubic meters per hour of pregnant solution and 162 electrowinning cells.

Plant and equipment are supported by a maintenance plan and a quality management system to assure good physical condition and high availability. The SXEW plant management quality system (including leaching operations) has been audited periodically since 2002 by an external audit company, and found to be in compliance with the requirements of the ISO 9001-2008 standard. In 2012, we obtained the certification OHSAS 18001 of our occupational health and safety system and the ISO14001-2004 for our environmental standards at the SX-EW plant.

Geology

The Cuajone porphyry copper deposit is located on the western slopes of Cordillera Occidental, in the southern-most Andes Mountains of Peru. The deposit is part of a mineral district that contains two additional known deposits, Toquepala and Quellaveco. The copper mineralization at Cuajone is typical of porphyry copper deposits.

The Cuajone deposit is located approximately 28 kilometers from the Toquepala deposit and is part of the Toquepala Group dated 60 to 100 million years (Upper Cretaceous to Lower Tertiary). The Cuajone lithology includes volcanic rocks from Cretaceous to Quaternary. There are 32 rock types including, pre-mineral rocks, basaltic andesite, porphyritic rhyolite, Toquepala dolerite and intrusive rocks, including diorite, porphyritic latite, breccias and dikes. In addition, the following post-mineral rocks are present, the Huaylillas formation which appears in the south-southeast side of the deposit and has been formed by conglomerates, tuffs, traquites and agglomerates. These formations date 17 to 23 million years and are found in the Toquepala Group as discordance. The Chuntacala formation which dates 9 to 14 million years and is formed by conglomerates, flows, tuffs and agglomerates placed gradually in some cases and in discordance in others. Also Quaternary deposits are found in the rivers, creeks and hills. The mineralogy is simple with regular grade distribution and vertically funnel-shaped. Ore minerals include chalcopyrite (CuFeS2), chalcosine (Cu2S) and molybdenite (MoS2) with occasional galena, tetraedrite and enargite as non economical ore.

Mine Exploration

Exploration activities during the drill campaign in 2012 are as follows:

Concentrator

Our Cuajone operations use state of the art computer monitoring systems at the concentrator, the crushing plant and the flotation circuit in order to coordinate inflows and optimize operations. Material with a copper grade over 0.40% is loaded onto rail cars and sent to the milling circuit, where giant rotating crushers reduce the size of the rocks 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 to produce foam for floating the copper and molybdenum minerals, but separating waste material called tailings. This copper-molybdenum bulk concentrate is then treated by inverse flotation where molybdenum is floated and copper is depressed. The copper concentrate is shipped by rail to the smelter at Ilo and the molybdenum concentrate is packaged for shipment to customers. Sulfides under 0.40% copper are considered waste.

Tailings are sent to thickeners where water is recovered. The remaining tailings are sent to the Quebrada Honda dam, our principal tailings storage facility.

Major Cuajone concentrator plant equipment includes: one primary crusher, three secondary crushers, seven tertiary crushers, eleven primary ball mills, four ball mills for re-grinding rougher concentrate, one vertical mill for re-grinding rougher concentrate, thirty 100-cubic feet cells for rougher flotation, four 160-cubic feet cells for rougher flotation, five 60-cubic feet cells for cleaner scavenger, six 1,350-cubic feet cells for cleaner scavenger, fourteen 300-cubic feet cells for cleaner scavenger, eight column cells, one Larox filter press, one FLS Smith filter press, two thickeners for copper-molybdenum and copper concentrates, three tailings thickeners, one high-rate tailings thickener, and six pumps for recycling reclaimed water.

A major mill expansion was completed in 1999 and the eleventh primary mill was put in operation in January 2008. We believe the plant’s equipment is in good physical condition and suitable for our operations.

Smelter

Our Ilo smelter produces copper anodes for the refinery we operate as part of the same facility. Copper produced by the smelter exceeds the refinery’s capacity and the excess is sold to other refineries around the world. In 2007 we completed a major modernization of the smelter. The nominal installed capacity of the smelter is 1,200,000 tons of concentrate per year.

Copper concentrates from Toquepala and Cuajone are transported by railroad to the smelter, where they are smelted using an ISASMELT furnace, converters and anode furnaces to produce copper anodes with 99.7% copper. At the smelter, the concentrates are mixed with flux and other material and sent to the ISASMELT furnace producing a mixture of copper matte and slag which is tapped through a taphole to either of two rotary holding furnaces, where these smelted phases will be separated. Copper matte contains approximately 63% copper. Copper matte is then sent to the four Pierce Smith converters, where the material is oxidized in two steps: (1) the iron sulfides in the matte are oxidized with oxygen enriched air and silica is added producing slag that is sent to the slag cleaning furnaces, and (2) the copper contained in the matte sulfides is then oxidized to produce blister copper, containing approximately 99.3% copper. The blister copper is refined in two anode furnaces by oxidation to remove sulfur with compressed air injected into the bath. Finally, the oxygen content of the molten copper is adjusted by reduction with injection of liquefied petroleum gas with steam into the bath. Anodes, containing approximately 99.7% copper are cast in two casting wheels. The smelter also can produce blister copper bars, especially when an anode furnace is in general repair.

Major equipment at the Ilo smelter includes One Isasmelt furnace, two rotary holding furnaces, four Pierce-Smith converters, two slag cleaning furnaces, two anodes furnaces, one casting twin-wheel, one blister holding furnace, one casting blister wheel, one waste heat boiler, one superheated steam, and three electrostatic precipitators.

The off gases from the smelter are treated to recover over 92% of the incoming sulfur received in the concentrates producing 98.5% sulfuric acid. The gas stream from the smelter with 11.34% SO2 is split between two plants: The No. 1 acid plant (single absorption/single contact) and the No. 2 plant (double absorption/double contact). Approximately, 16% of the acid produced is used at our facilities with the balance sold to third parties. We anticipate that our internal usage will be over 80% when the Tia Maria project begins operation.

The smelter also has two oxygen plants. Plant No. 1, with 254 tons per day of production capacity and Plant No.2, with 1,045 tons per day of capacity.

In addition, the smelter includes a seawater intake system, two desalinization plants to provide water for the process, an electric substation and one centralized control using advanced computer technology.

In 2010, the Ilo smelter marine trestle started operation. This facility allows us to offload directly to offshore ships the sulfuric acid produced, avoiding hauling cargo through the city of Ilo. The 500 meter long marine trestle is the last part of the Ilo smelter modernization project. Currently all overseas shipments of sulfuric acid are being made using the marine trestle.

Refinery

The Ilo refinery consists of a receiving and preparing anode facility, an electrolytic plant, a precious metal plant and a number of ancillary installations. The refinery is producing grade A copper cathode of 99.998% purity. The nominal capacity is 280,000 tons per year. Anodic slimes are recovered from the refining process and then sent to the precious metals facility to produce refined silver, refined gold and commercial grade selenium.

Anodes are suspended in tanks containing an aqueous solution of sulfuric acid and copper sulfate. A low voltage but high amperage electrical current is passed through the anodes, chemical solution and cathodes, in order to dissolve copper which is deposited on initially very thin starting sheets increasing its thickness to produce high grade copper cathodes containing at least 99.99% copper. During this process, silver, gold and other metals, including palladium, platinum and selenium, along with other impurities, settle on the bottom of the tank in the form of anodic slime. This anodic slime is processed in a precious metal plant where silver, gold and selenium are recovered.

Major equipment at the refinery includes One electrolytic plant, with 926 commercial cells, fifty-two starting sheet cells, sixteen primary liberator cells, twenty-four secondary liberator cells, one anodic slime treatment circuit (includes leaching and centrifugation), and one electrolytic bleeding-off system by railroad to Toquepala’s leaching plants.

Main equipment at the precious metals plant includes one selenium reactor and system to produce commercial grade selenium powder, one Wenmec anodic slime roaster reactor, one tilting Copella furnace, twenty-six silver electrorefining cells including an induction furnace for shots and silver ingots production, and one hydrometallurgical system for gold recovery.

The refinery also has these facilities:

2. (1) Production control: Provides sampling and sampling preparation for samples coming from the operating units, as well as SXEW, smelter and external services.
3. (2) Laboratory: Provides sample analysis services throughout the Company, including the analysis of final products like copper cathodes, electrowon cathodes, copper concentrates and oil analysis.
4. (3) Maintenance: Responsible for maintenance of all equipment involved in the process.
5. (4) Auxiliary facilities: Includes one desalinization plant to produce 1,000 cubic meters per day fresh water and a Gonella boiler to produce steam used in the refinery, one Babcock boiler used as spare and two stand-by KMH boilers.

Other facilities in Ilo are a coquina plant with a production capacity of 200,000 tons per year of seashells and a lime plant with a capacity of 80,000 tons per year. We also operate an industrial railroad to haul production and supplies between Toquepala, Cuajone and Ilo.

The industrial railroad’s main equipment includes fifteen locomotives of different types including 4000HP EMD’s SD70, 3000HP EMD’s GP40-3, 2250HP GE U23B and others. The rolling stock has approximately 496 cars of different types and capacities, including ore concentrate cars, gondolas, flat cars, dump cars, boxcars, tank cars and others. The track runs in a single 214 kilometer standard gauge line and supports a 30-ton axle load. The total length of the track system is around 257 kilometers including main yards and sidings.

The infrastructure includes 27 kilometers of track under tunnels and one concrete bridge. The industrial railroad includes a car repair shop which is responsible for maintenance and repair of the car fleet. Annual tonnage transported is approximately 5.1 million tons.

Mine Exploration

During 2011 at Nueva Rosita, 2,640 meters of diamond drilling were performed at the Esperanzas and Nueva Rosita open pits. Through this drilling we identified approximately 0.18 million tons of coal reserves.