Minera San Cristobal
Encyclopedia
Minera San Cristobal S.A. (MSC) is a world-class Bolivian mining company that focuses on mining for silver
, lead
and zinc
in the remote province of Nor Lipez in the Bolivian department of Potosi. Minera San Cristobal is a wholly owned subsidiary of the Sumitomo Corporation
, one of Japan’s leading industrial groups.
The first drilling activities started in August 1996 when Apex Silver Mines Limited
was established with the purpose of purchasing and developing silver, zinc and lead exploitation projects worldwide.
In February 2000, Minera San Cristobal S.A. (MSC) was incorporated and ASC Bolivia LDC transferred all its mining concessions in the district of San Cristobal to MSC. The company launched a program to build and remodel mining camps, requiring significant investments in machinery and equipment.
In 2006, the Sumitomo Corporation acquired 35 percent of MSC’s shares from majority shareholder Apex Silver Mines Ltd. Three years later, MSC became a wholly owned subsidiary of the Sumitomo Corporation.
The principal deposit is made up of two mineralized zones, known as Jayula and Tesorera, which are lodged in the central part of a volcanic sedimentary basin that is four kilometers (≈2.5 mi) in diameter. Located three kilometers (≈1.86 mi) southwest of Tesorera is another deposit known as Animas.
The principal minerals of economic interest in these deposits are sphalerite
, galena
and argentite
, which correspond to zinc, lead and silver sulfides, respectively.
is used.
In order to quantify the mine’s reserves, approximately 160,000 meters of holes were drilled. Based on the results of this extensive drilling program, it was determined the mine contained 226 million metric tons of proven and probable sulfide reserves, grading 1.68 percent of zinc, 0.53 percent of lead and 51 grams of silver per ton.
method, using state-of-the-art equipment and machinery. Mineral Reserves Associates (MRA) originally designed and planned the mining operation, using the floating cone technique. At present, all the design and planning is done at the site.
Ore
extracted from the open pit is transported to the crushing plant using 200-ton trucks, and the waste is taken and deposited in storage dumps. Once crushed, the ore is then transported over a 1.7 kilometer-long (1 mile) overland conveyor belt to the concentration plant.
This production rate requires the daily moving of 150,000 tons of rock, of which 40,000 tons of ore grade are transported to the concentration plant for treatment. The concentration plant consists of a primary crusher
, a 1.7 kilometer-long (1 mile) overland conveyor belt, a milling circuit with a semi-autogenous (SAG) mill and two ball mill
s. It also has cyclone banks for recirculation and size classification of the load, a differential flotation circuit where the two types of concentrates are separated, and a filtration and drying plant.
to the San Cristobal mine, stretching 100 kilometers (≈62 miles), and includes two bridges spanning the Colorado
and Grande de Lipez rivers.
The second road links the mine to the train station in Avaroa, at the Bolivian border with Chile
. This road is 135 km long (≈84 miles), and connects the Ollague – Calama – Antofagasta road.
station. At this point it connects to the Uyuni – Estacion Avaroa – Mejillones railroad.
Total hauling distance from the Toldos plant in San Cristobal (Bolivia) to the Mejillones
port (Chile) is approximately 650 kilometers (≈400 miles). The railway serves as the only means of transportation for concentrates being transported from the production facility to the seaport. Zinc-silver and lead-silver concentrates produced by MSC are transported from the plant to the port in sealed cylindrical metal containers, with an estimated capacity of 21 tons each.
On an average day, the mine exports approximately 1,300 tons of zinc-silver concentrate and 300 tons of lead-silver concentrate.
The runway is 2,400 meters (≈7,800 feet) in length. The facility was designed to service both executive planes and larger aircrafts. The strip is properly equipped and authorized for nighttime operations in case of emergency. It is owned and operated by MSC.
A Town Move Commission was created, and members visited the nearby towns of Quechisla, Tupiza and Uyuni to study their architectural styles and speak with community leaders about relocating the town and the church of San Cristobal. The company submitted a proposal to the residents of San Cristobal, who provided feedback and suggested revisions.
On June 9, 1998, the Agreement for Relocation of the village was signed, and was ratified by the prefect of Potosi and the president of the Civic Committee of Potosi (COMCIPO). The agreement was also officially approved by the vice minister of mining, the municipal mayor and the municipal agent.
In order to ensure transparency, quality and efficiency, all construction work was supervised by an independent construction firm. All community stakeholders had a role in the planning and development process.
The newly constructed community consists of a hospital, chapel, school, city hall, sports and athletic fields, 145 houses, roads, sanitary facilities, and electricity. The new town of San Cristobal was officially inaugurated with a special ceremony on June 9, 1999.
Soon after the new town was populated, the rights to the mine were transferred to a newly incorporated company known as Minera San Cristobal.
Minera San Cristobal retains the dedication to the new community, including maintaining its new improved standards of sanitation, security and well-being.
In 1998, the company met with the community of San Cristobal to relocate the town safely away from the location where mining operations were about to start. The company invested more than US $400,000 to ensure that the move occurred safely and without incident. The efforts to move the church were undertaken in keeping with international standards and traditions for moving religious structures with all due reverence and care. Local and regional religious leaders were consulted and had significant input in the process to relocate the church safely and effectively.
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
, lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
and zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
in the remote province of Nor Lipez in the Bolivian department of Potosi. Minera San Cristobal is a wholly owned subsidiary of the Sumitomo Corporation
Sumitomo Corporation
Sumitomo Corporation is one of the largest worldwide trading company , and is a diversified corporation. Sumitomo is headquartered in the Harumi Island Triton Square Office Tower Y in Chūō, Tokyo, Japan...
, one of Japan’s leading industrial groups.
History
In 1994, the Andean Silver Corporation, and its subsidiary ASC Bolivia LDC, were incorporated for developing mining projects in South America. A partnership with MINTEC, a leading Bolivian mining consulting company, provided the option to buy concessions from the San Cristobal and Toldos groups.The first drilling activities started in August 1996 when Apex Silver Mines Limited
Apex Silver Mines
Apex Silver Mines from Denver, Colorado was a US-American transnational mining corporation with a tax haven address in the Cayman Islands.Since its start in 1993, Apex Silver Mines Ltd...
was established with the purpose of purchasing and developing silver, zinc and lead exploitation projects worldwide.
In February 2000, Minera San Cristobal S.A. (MSC) was incorporated and ASC Bolivia LDC transferred all its mining concessions in the district of San Cristobal to MSC. The company launched a program to build and remodel mining camps, requiring significant investments in machinery and equipment.
In 2006, the Sumitomo Corporation acquired 35 percent of MSC’s shares from majority shareholder Apex Silver Mines Ltd. Three years later, MSC became a wholly owned subsidiary of the Sumitomo Corporation.
Ore deposits
San Cristobal has been a renowned source of silver production since the 1500s. Since then, the area has been one of the most abundant sources of silver in the Western hemisphere.The principal deposit is made up of two mineralized zones, known as Jayula and Tesorera, which are lodged in the central part of a volcanic sedimentary basin that is four kilometers (≈2.5 mi) in diameter. Located three kilometers (≈1.86 mi) southwest of Tesorera is another deposit known as Animas.
The principal minerals of economic interest in these deposits are sphalerite
Sphalerite
Sphalerite is a mineral that is the chief ore of zinc. It consists largely of zinc sulfide in crystalline form but almost always contains variable iron. When iron content is high it is an opaque black variety, marmatite. It is usually found in association with galena, pyrite, and other sulfides...
, galena
Galena
Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...
and argentite
Argentite
Argentite was primarily treated as a mineral belonging to the galena group, cubic silver sulfide , occasionally found as uneven cubes and octahedra, but more often as dendritic or earthy masses, with a blackish lead-grey color and metallic lustre. All these forms are structurally not argentite, but...
, which correspond to zinc, lead and silver sulfides, respectively.
Type of mineralization
The San Cristobal deposit is characterized by mineralization in the form of thin veins, veinlets and disseminations, which combine to form a low-grade mineral deposit. While extensive, the deposit cannot be efficiently tapped using traditional underground mining methods, for which an open-pit systemSurface mining
Surface mining , is a type of mining in which soil and rock overlying the mineral deposit are removed...
is used.
In order to quantify the mine’s reserves, approximately 160,000 meters of holes were drilled. Based on the results of this extensive drilling program, it was determined the mine contained 226 million metric tons of proven and probable sulfide reserves, grading 1.68 percent of zinc, 0.53 percent of lead and 51 grams of silver per ton.
Mining
The San Cristobal mine operates under the open-pitSurface mining
Surface mining , is a type of mining in which soil and rock overlying the mineral deposit are removed...
method, using state-of-the-art equipment and machinery. Mineral Reserves Associates (MRA) originally designed and planned the mining operation, using the floating cone technique. At present, all the design and planning is done at the site.
Ore
Ore
An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....
extracted from the open pit is transported to the crushing plant using 200-ton trucks, and the waste is taken and deposited in storage dumps. Once crushed, the ore is then transported over a 1.7 kilometer-long (1 mile) overland conveyor belt to the concentration plant.
Production
The mine produces approximately 1,300 metric tons per day of zinc-silver concentrates and 300 metric tons per day of lead-silver concentrates, attaining an estimated annual output volume of 600,000 tons of concentrates.This production rate requires the daily moving of 150,000 tons of rock, of which 40,000 tons of ore grade are transported to the concentration plant for treatment. The concentration plant consists of a primary crusher
Crusher
A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or recycled, or to reduce the size of a solid mix of raw materials , so that pieces...
, a 1.7 kilometer-long (1 mile) overland conveyor belt, a milling circuit with a semi-autogenous (SAG) mill and two ball mill
Ball mill
A ball mill is a type of grinder used to grind materials into extremely fine powder for use in mineral dressing processes, paints, pyrotechnics, and ceramics.-Description:...
s. It also has cyclone banks for recirculation and size classification of the load, a differential flotation circuit where the two types of concentrates are separated, and a filtration and drying plant.
Roads
Two-way gravel roads were constructed to facilitate the transportation of personnel, materials, input and machinery, both from within Bolivia and from the ports. The first road connects the town of UyuniUyuni
Uyuni is a city in the southwest of Bolivia. It primarily serves as a gateway for tourists visiting the world's largest salt flats, the nearby Salar de Uyuni.-Origin:...
to the San Cristobal mine, stretching 100 kilometers (≈62 miles), and includes two bridges spanning the Colorado
Colorado
Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...
and Grande de Lipez rivers.
The second road links the mine to the train station in Avaroa, at the Bolivian border with Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...
. This road is 135 km long (≈84 miles), and connects the Ollague – Calama – Antofagasta road.
Railway
To move the zinc-silver and lead-silver concentrates from San Cristobal to the world, a special railroad, 1 meter wide, and 65 kilometres (40.4 mi) long was constructed from the concentration plant to the Río GrandeRio Grande
The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...
station. At this point it connects to the Uyuni – Estacion Avaroa – Mejillones railroad.
Total hauling distance from the Toldos plant in San Cristobal (Bolivia) to the Mejillones
Mejillones
Mejillones is a Chilean port city and commune in Antofagasta Province, Antofagasta Region. Its name is the plural form of the Spanish mejillón meaning "mussel", referring to a particularly abundant species and preferred staple food of its indigenous inhabitants. It is situated in the northern side...
port (Chile) is approximately 650 kilometers (≈400 miles). The railway serves as the only means of transportation for concentrates being transported from the production facility to the seaport. Zinc-silver and lead-silver concentrates produced by MSC are transported from the plant to the port in sealed cylindrical metal containers, with an estimated capacity of 21 tons each.
On an average day, the mine exports approximately 1,300 tons of zinc-silver concentrate and 300 tons of lead-silver concentrate.
Air Transportation
Six kilometers (≈3.7 miles) south of the MSC processing plant is a private landing strip providing air service for the mine.The runway is 2,400 meters (≈7,800 feet) in length. The facility was designed to service both executive planes and larger aircrafts. The strip is properly equipped and authorized for nighttime operations in case of emergency. It is owned and operated by MSC.
Triple Certification
- MSC is proud to be recognized for having achieved the requirements for three certifications: ISO 9001 certification, the international process establishing the standards for quality management systems; ISO 14001 certification, an environmental management standard; and the OHSAS 18001 certification, which outlines parameters for health and safety.
- OHSAS 18001 certification is a voluntary international standard against which organizations are assessed on their health and safety performance. Its purpose is to help organizations control occupational health and safety risks.
- ISO 9001, awarded to MSC on May 10, 2010, certification is an internationally recognized standard for the quality management of businesses.
- ISO 14001, awarded to MSC on May 31, 2010, is a standard for environmental management systems that aims to reduce the environmental footprint of a business and to decrease the pollution and waste it produces.
Community Relations
Social responsibility and community efforts led to the construction of a new village at San Cristobal and relocation of its historic church. The new community includes significant upgrades to its infrastructure, including providing residents with reliable power, water and sanitation for the first time.Moving the Town
In 1998, negotiations began with locals to relocate the village and upgrade the quality of life of its residents. The town was located in an area close to major ore deposits.A Town Move Commission was created, and members visited the nearby towns of Quechisla, Tupiza and Uyuni to study their architectural styles and speak with community leaders about relocating the town and the church of San Cristobal. The company submitted a proposal to the residents of San Cristobal, who provided feedback and suggested revisions.
On June 9, 1998, the Agreement for Relocation of the village was signed, and was ratified by the prefect of Potosi and the president of the Civic Committee of Potosi (COMCIPO). The agreement was also officially approved by the vice minister of mining, the municipal mayor and the municipal agent.
In order to ensure transparency, quality and efficiency, all construction work was supervised by an independent construction firm. All community stakeholders had a role in the planning and development process.
The newly constructed community consists of a hospital, chapel, school, city hall, sports and athletic fields, 145 houses, roads, sanitary facilities, and electricity. The new town of San Cristobal was officially inaugurated with a special ceremony on June 9, 1999.
Soon after the new town was populated, the rights to the mine were transferred to a newly incorporated company known as Minera San Cristobal.
Minera San Cristobal retains the dedication to the new community, including maintaining its new improved standards of sanitation, security and well-being.
Moving the Church
The colonial church at the Bolivian village of San Cristobal was declared a national monument in December 1967. While the exact date for the initial construction of the church has been lost, it appears in chronicles from the 1600s as already being in existence.In 1998, the company met with the community of San Cristobal to relocate the town safely away from the location where mining operations were about to start. The company invested more than US $400,000 to ensure that the move occurred safely and without incident. The efforts to move the church were undertaken in keeping with international standards and traditions for moving religious structures with all due reverence and care. Local and regional religious leaders were consulted and had significant input in the process to relocate the church safely and effectively.