Current mining is made up of several stages, from the discovery of the deposit, through exploitation, to finally the closure and post-closure of the mine. The first phase is the discovery of the deposit, which is carried out through prospecting and exploration, the objective of which is to know and define the extent, location and value of the mineral. Once that is done and through statistical and mathematical calculations, the size and grade of the deposit is estimated and used to create the pre-feasibility study, which theoretically determines the economics of the deposit, the initial investment and the possible key risks. The next step is the feasibility study, which evaluates the economic viability, technical and financial risks and the soundness of the project.

Both studies provide the mining company with as much information as possible about the deposit, with which they make the decision to invest or abandon the project. If the mineral deposit is economically viable, the mining company begins to plan how it will be extracted, the metallurgy, the amount of mineral to be recovered, the possible buyers and the type of concentrate that will be obtained. In addition, it is concerned with engineering, the costs of comminution and infrastructure, the legal and environmental requirements demanded by the mining institutes of each country, but above all how to obtain the necessary capital to operate the mine extraction.

To access the deposit mine it is necessary to extract the material that has no economic interest, also known as gangue. In the vast majority of cases the amount of gangue is double the mineral that is extracted during the entire life of the mine, therefore the company must consider removing and placing said waste. The establishment of the so-called tailings dams must have a detailed study of the geography of the place, to avoid possible environmental risks that could affect the fauna, flora and communities adjacent to the mine. Once the construction of the plant and the tailings dam is defined, the extraction and marketing of the mineral begins. The functionality and duration of the mine depends on the amount of mineral that the deposit has, and whether, over the years, its extraction continues to be economically profitable.

After several years of operation, the mining company must begin the closure and post-closure of the mine, the process of which is gradual, therefore it can take a long time. According to the mining laws and codes of each country, the closure of the works may be definitive or, to a lesser extent, partial. The vast majority of nations with large-tonnage mining industries require total mine closure, which involves dismantling the plant facilities and closing the entrances to the mines that were exploited underground. This process may be accompanied by reforestation of the site, with the aim of reestablishing the geographical and environmental characteristics that existed prior to the initiation of operations.

Contenido

Para explotar un mineral existen dos métodos: la minería a cielo abierto y la mina subterránea, siendo la primera la más común hoy en día. Según el investigador H.L. Hartmann en su ensayo Introductory Mining Engineering, la minería a cielo abierto produce el 85% de los minerales extraídos en los Estados Unidos, de los cuales el 95% de ellos corresponde a minerales metálicos.[28]​ Dentro de la minería a cielo abierto se encuentra la de los depósitos en placeres (también denominados yacimientos de tipo placer), que permite obtener valiosos minerales contenidos en la grava de los ríos, arena de playa o en sedimentos producidos por aluviones, cuyo proceso de extracción varía en ocasiones a los empleados en las minas a cielo abierto.[29]​.

Sin embargo, y en ciertas ocasiones específicas como en la extracción del uranio y de las tierras raras, existen métodos poco comunes, tales como la lixiviación in situ"). Esta nueva técnica consiste en crear hoyos desde la superficie hasta el respectivo depósito, pero aun así no se considera como un método a cielo abierto ni subterráneo. Para llevar a cabo la lixiviación in situ se requiere que los minerales sean solubles en agua como por ejemplo el potasio, cloruro de potasio, cloruro de sodio y sulfato de sodio. Otros minerales como los óxidos de uranio") y cobre necesitan soluciones de ácido o de carbonato para su disolución y posterior extracción.[30]​.

Open pit mining

Open pit mining or also called surface mining is carried out by removing vegetation (stripping) and the upper layers of rock, in order to reach the buried deposits. Surface mining can be divided into open pit mining —in our language known simply as a pit mine or open pit— which consists of the extraction of minerals through a huge pit in the ground, which can even reach several kilometers in length; quarrying, identical to open pit mining, but used in rock, sand and clay deposits;[31] (topography)") of the mountain where the deposit is located, mainly coal.[33]​ Within open pit mining there are placer deposits and the technique called landfill mining and reclamation (LFMR), which consists of extracting already processed minerals from the garbage of landfills "Landfill (garbage)").[34]​.

Underground mining

Underground mining or sometimes called subsoil mining is carried out by building tunnels or galleries, with the aim of penetrating the rock to reach the deposits. This type of method is classified according to the form of access; drift mining (horizontally), slope mining (diagonally) and shaft mining (vertically), or according to the extraction technique; of sinking or large blocks. Among those for caving are block caving, sublevel caving and panel caving, while stopes are divided into empty (sublevel stoping and vertical crater retreat (VCR)), supported (cut & fill and shrinkage) and self-supporting (open stopes and room & pillar).[35]​[36]​.

Mining at the bottom of the sea

Seabed mining, also known as underwater mining, is a relatively new mineral extraction process that takes place on the seabed. Ocean mining deposits are usually made around large areas of polymetallic nodules or active or extinct hydrothermal vents about 1,400-3,700 meters below the ocean surface. Hydrothermal vents create sulfide deposits containing precious metals such as silver, gold, copper, manganese, cobalt and zinc. The deposits are extracted using hydraulic pumps or bucket systems that bring the ore to the surface for processing.

Una vez que el mineral es extraído tiene que ser procesado de acuerdo a ciertos protocolos analizados durante años. La ciencia que estudia dicho proceso es la metalurgia extractiva, que es un área de la metalurgia que estudia la extracción de los metales preciosos de los minerales mediante medios químicos, mecánicos o electrolíticos.[38]​ Uno de los estudios de dicha ciencia es el procesamiento de minerales, que analiza los medios mecánicos de trituración, molienda y lavado, que permite la separación de los metales con valor económico de la ganga. Como la gran mayoría de los metales están presentes en los minerales de óxido y sulfuros, es necesario procesarlos mediante la fundición "Fundición (metalurgia)") o por medio de la reducción electrolítica. La ciencia que combina todos estos procesos ya sea la minería, la metalurgia extractiva y las ciencias geológicas, además de la economía del yacimiento y los posibles daños medioambientales, se denomina geometalurgia.[39]​.

Productive circuit

The production circuit, or also called the production process, is defined as the stages through which a mineral undergoes until it becomes a marketable product. Below is a list of the main processes that are applied to a metallic mineral. Of course, this list is a general one, since depending on the metal some threads may be included.

Al igual que muchas de las actividades humanas la minería produce serios problemas al medio ambiente, debido a sus diversos procesos mineros y químicos. Estos efectos pueden incluir erosión, formación de dolinas "Dolina (geología)"), pérdida de la biodiversidad, contaminación de las aguas subterráneas y superficiales, como también contaminación del suelo. En algunos casos, se incluye como factor adicional la deforestación en torno a la mina, con el objetivo de crear espacio suficiente para las instalaciones necesarias para su funcionamiento y el almacenamiento de residuos. Por su parte, la contaminación resultante de las fugas de sustancias químicas afecta directamente a la población local, si no se controla adecuadamente.[40]​ Un caso extremo de daño ambiental es el incendio en la mina de carbón de Centralia en Pensilvania, que desde 1962 arde por sus túneles ubicados debajo de la localidad estadounidense.[41]​.

En muchos países, las compañías mineras están obligadas a seguir y cumplir estrictos códigos de protección del medio ambiente con el fin de minimizar su impacto ambiental y evitar eventuales problemas a la comunidad adyacente. Estos códigos o reglamentos obligan a las mineras a realizar la evaluación de impacto ambiental, desarrollar planes de gestión ambiental, programar el cierre de la mina y elaborar monitoreos ambientales durante la operación y después del cierre. Por su parte, si las grandes compañías requieren buscar financiamiento internacional en instituciones como Equator Principles") y en la Corporación Financiera Internacional, deben cumplir otra serie de normas ambientales y, además, satisfacer los criterios de la inversión socialmente responsable.

Más allá de las exigencias establecidas por las instituciones financieras o por los organismos gubernamentales de cada país, con los años las grandes compañías mineras han autoregulado sus efectos al medio ambiente mediante una serie de códigos de conducta. En 2001, nueve de las grandes compañías crearon el Consejo Internacional de Minería y Metales") (ICMM, por sus siglas en inglés), cuyo objetivo es mitigar el daño al medio ambiente, reducir, reutilizar y reciclar los insumos, integrar en el concepto de mercado el desarrollo sustentable y contribuir a la conservación de la biodiversidad, entre otros puntos.[42]​ Actualmente, 23 compañías mineras y de metales en conjunto con 35 asociaciones mineras nacionales y regionales integran este consejo internacional. A su vez, algunas de ellas son miembros activos en la creación de políticas de ecoeficiencia de organizaciones como la Cámara de Comercio Internacional y el Consejo Empresarial Mundial para el Desarrollo Sostenible.[43]​.

Tailings contamination

One of the main elements of pollution generated by the mining industry is that caused by tailings, which are classified as sterile or mineralized waste, with high levels of acids and chemicals, and whose storage is an important part of the mine planning process. In simple terms, a tailings is the gangue or material that is not economically viable from the extractive process of the mining operation, the quantities of which vary depending on the metal to be extracted. For example, a mineral that contains 20% metal will produce about 4 tons of tailings, while if it has only 1% metal, its extraction could generate up to 99 tons of tailings.[44]​ In the case of gold mining, considered one of the highest gangue producers in the industry, only 5.3 grams of gold are obtained for each ton, that is, to achieve one ton of Au, about 200,000 tons of Au will be produced. tailings.[45]​.

To store the tailings, dams are built, which are engineering works made up of a retaining wall and a bucket, and which serve the same purpose as dams.[46] Until 2000, it was estimated that there were 3,500 dams in operation and that every year between two or three large dams and 35 smaller ones were created. Poor planning and construction can lead to severe risks for their environment, due to the failure of the retaining wall produced by the pressure of the tailings, the dragging of waste due to extensive rainfall, filtration of its waters to the surroundings and infiltration under the dam, lifting and dragging of fine material due to the wind, among others.[46]​ The collapse of a dam causes critical contamination in surface and underground waters, biodiversity, soil and surrounding populations due to the high concentrations of acid, mercury "Mercury (element)"), iron, arsenic and lead, among other chemicals typical of mineral processing.

Throughout history there have been serious accidents caused by the spill of tailings, for example, in 1965 and after an earthquake the dam of the El Soldado Mine collapsed, located in the commune of Nogales "Nogales (Chile)") in Chile, whose contamination spread for hundreds of kilometers, completely burying the El Cobre mining camp and causing the death of 200 people.[47]​ In 1996, in the Marcopper mine in On the Philippine island of Marinduque, 1.6 million cubic meters contaminated 27 kilometers of the banks of the Boac River and the coastal area. Its devastation meant the death of fish, river shrimp and pigs, the contamination of drinking water sources, the complete destruction of the Hinapulan barangay, the isolation of more than 20,000 people and the evacuation of a third of the villages in the province of Marinduque.[48]

For its part, on November 5, 2015, the worst tailings disaster in South America occurred when two dams at the Samarco Mineração S.A. mine, a company created by Vale S.A. and BHP Billiton, collapsed in the Bento Rodrigues subdistrict in the state of Minas Gerais in Brazil. In total, it was estimated that 55 million cubic meters of mud and iron ore waste killed the biodiversity of the Doce River, destroyed a town of 300 families, forced the suspension of water supplies to more than 250,000 people, left 15 dead and 12 missing, and left hundreds of millions of dollars in material and natural losses. Even, months later, it was confirmed that its waste reached Regencia beach in the state of Espírito Santo.[49][50]​.

La minería como industria ocurre en varios países del mundo, siendo Londres la capital mundial de esta actividad. La ciudad británica es la sede del principal mercado del mundo en transacción de metales no ferrosos y es la sede de las principales compañías mineras, tales como Rio Tinto Group, BHP Billiton y Anglo American. Otro mercado de importancia es el New York Mercantile Exchange, donde se contratan derivados financieros de algunos metales preciosos y productos energéticos como el petróleo y gas natural. Por último, la Bolsa de Shanghái está enfocada para aquellos países que exportan minerales a China, como por ejemplo las naciones situadas en las orillas del Océano Pacífico.[51]​ En el caso de los Estados Unidos la minería es considerada como una gran actividad financiera; sin embargo, está dominada por el carbón y la minería no metálica. No obstante, durante los últimos años diversos reglamentos han tratado de reducir la importancia de la actividad en el país.[52]​ En otros países anglosajones como Canadá y Australia, la minería desde hace décadas se ha convertido en parte significativa de la economía interna.

En 2002, la OCDE situó a Chile y Perú como los principales productores de minerales de Sudamérica y estimó que tenían un gran potencial económico durante los próximos años en dicho rubro.[53]​ Por su parte, la industria en África es una de las más importantes y a su vez emergentes, ya que a pesar de que su participación en la producción de cobre, plomo y zinc es relativamente menor, se estima que el continente posee un importante porcentaje de minerales del mundo, como por ejemplo el 40% de reservas de oro, el 60% de cobalto y el 90% de los minerales del grupo del platino.[54]​ En 2010, dos de las cuatro economías que más crecieron en el mundo son exportadores de minerales y a su vez africanas, Botsuana y República del Congo, mientras que las otras dos son exportadoras de petróleo.[55]​ En cuanto a los minerales de tierras raras, en 2013 China controlaba el 95% de la producción mundial de mencionados elementos.[56]​ Por su parte, Chile es el principal exportador de yodo con el 60% de la producción mundial y además, es el único productor global de nitratos o salitre.[57]​.

Mining classification

Each mineral-producing country uses various criteria to organize industry production and have a better understanding of its impact on the regional and national economy. The vast majority of countries use the criterion of the number of metric tons produced per year, although in some specific cases the capital of the mine, infrastructure or job creation is also included. Broadly speaking, the industry is classified into large, medium and small mining; However, in some countries such as Peru, a fourth classification is considered, artisanal mining.[58] Below are the characteristics of the three main divisions of mining and an example of the production figures required by the laws of Chile and Peru, considered by the OECD as the main mineral-producing countries in South America.

Mining companies

Mining companies are companies that carry out various activities to transform raw materials into specific products, whose competence depends on the production of extracted mineral and its quality and quantity.[60] Many of the large companies are multinational, private in nature and also with capital open to the public in international markets. However, there are certain public or state companies with a large market share, such as the Chilean Codelco and the Indian National Mineral Development Corporation.

For their part, mining companies are classified into five categories according to the extraction and commercialization of the respective resources. These are oil and gas, coal mining, metallic minerals, non-metallic minerals and quarries, and mining support activities.[61]​ Another way of classification is according to the net annual income earned by a company, classified as follows:[62]​.

In 2012, the services firm PwC made a list of the main mining companies worldwide, where it also highlighted the number of companies per country. In first place was Canada with nine companies, followed by England with seven and the United States with five.[55] It should be noted that BHP Billiton and Rio Tinto Group appear in both England and Australia, because they have capital from both countries. The same happens with Antofagasta plc, since it has capital from England and Chile.

Main mineral producers worldwide

In 2012, the United States Geological Survey (USGS) made a table with the largest gold, silver, copper and nickel producing countries worldwide. In turn, they were classified as developed, countries that have a track record in the field, emerging, countries that in recent decades have increased their participation worldwide, and developing, countries that have just begun large-scale activity. 16% nickel.[55]​.

Current mining is made up of several stages, from the discovery of the deposit, through exploitation, to finally the closure and post-closure of the mine. The first phase is the discovery of the deposit, which is carried out through prospecting and exploration, the objective of which is to know and define the extent, location and value of the mineral. Once that is done and through statistical and mathematical calculations, the size and grade of the deposit is estimated and used to create the pre-feasibility study, which theoretically determines the economics of the deposit, the initial investment and the possible key risks. The next step is the feasibility study, which evaluates the economic viability, technical and financial risks and the soundness of the project.

Both studies provide the mining company with as much information as possible about the deposit, with which they make the decision to invest or abandon the project. If the mineral deposit is economically viable, the mining company begins to plan how it will be extracted, the metallurgy, the amount of mineral to be recovered, the possible buyers and the type of concentrate that will be obtained. In addition, it is concerned with engineering, the costs of comminution and infrastructure, the legal and environmental requirements demanded by the mining institutes of each country, but above all how to obtain the necessary capital to operate the mine extraction.

To access the deposit mine it is necessary to extract the material that has no economic interest, also known as gangue. In the vast majority of cases the amount of gangue is double the mineral that is extracted during the entire life of the mine, therefore the company must consider removing and placing said waste. The establishment of the so-called tailings dams must have a detailed study of the geography of the place, to avoid possible environmental risks that could affect the fauna, flora and communities adjacent to the mine. Once the construction of the plant and the tailings dam is defined, the extraction and marketing of the mineral begins. The functionality and duration of the mine depends on the amount of mineral that the deposit has, and whether, over the years, its extraction continues to be economically profitable.

After several years of operation, the mining company must begin the closure and post-closure of the mine, the process of which is gradual, therefore it can take a long time. According to the mining laws and codes of each country, the closure of the works may be definitive or, to a lesser extent, partial. The vast majority of nations with large-tonnage mining industries require total mine closure, which involves dismantling the plant facilities and closing the entrances to the mines that were exploited underground. This process may be accompanied by reforestation of the site, with the aim of reestablishing the geographical and environmental characteristics that existed prior to the initiation of operations.

Contenido

Para explotar un mineral existen dos métodos: la minería a cielo abierto y la mina subterránea, siendo la primera la más común hoy en día. Según el investigador H.L. Hartmann en su ensayo Introductory Mining Engineering, la minería a cielo abierto produce el 85% de los minerales extraídos en los Estados Unidos, de los cuales el 95% de ellos corresponde a minerales metálicos.[28]​ Dentro de la minería a cielo abierto se encuentra la de los depósitos en placeres (también denominados yacimientos de tipo placer), que permite obtener valiosos minerales contenidos en la grava de los ríos, arena de playa o en sedimentos producidos por aluviones, cuyo proceso de extracción varía en ocasiones a los empleados en las minas a cielo abierto.[29]​.

Sin embargo, y en ciertas ocasiones específicas como en la extracción del uranio y de las tierras raras, existen métodos poco comunes, tales como la lixiviación in situ"). Esta nueva técnica consiste en crear hoyos desde la superficie hasta el respectivo depósito, pero aun así no se considera como un método a cielo abierto ni subterráneo. Para llevar a cabo la lixiviación in situ se requiere que los minerales sean solubles en agua como por ejemplo el potasio, cloruro de potasio, cloruro de sodio y sulfato de sodio. Otros minerales como los óxidos de uranio") y cobre necesitan soluciones de ácido o de carbonato para su disolución y posterior extracción.[30]​.

Open pit mining

Open pit mining or also called surface mining is carried out by removing vegetation (stripping) and the upper layers of rock, in order to reach the buried deposits. Surface mining can be divided into open pit mining —in our language known simply as a pit mine or open pit— which consists of the extraction of minerals through a huge pit in the ground, which can even reach several kilometers in length; quarrying, identical to open pit mining, but used in rock, sand and clay deposits;[31] (topography)") of the mountain where the deposit is located, mainly coal.[33]​ Within open pit mining there are placer deposits and the technique called landfill mining and reclamation (LFMR), which consists of extracting already processed minerals from the garbage of landfills "Landfill (garbage)").[34]​.

Underground mining

Underground mining or sometimes called subsoil mining is carried out by building tunnels or galleries, with the aim of penetrating the rock to reach the deposits. This type of method is classified according to the form of access; drift mining (horizontally), slope mining (diagonally) and shaft mining (vertically), or according to the extraction technique; of sinking or large blocks. Among those for caving are block caving, sublevel caving and panel caving, while stopes are divided into empty (sublevel stoping and vertical crater retreat (VCR)), supported (cut & fill and shrinkage) and self-supporting (open stopes and room & pillar).[35]​[36]​.

Mining at the bottom of the sea

Seabed mining, also known as underwater mining, is a relatively new mineral extraction process that takes place on the seabed. Ocean mining deposits are usually made around large areas of polymetallic nodules or active or extinct hydrothermal vents about 1,400-3,700 meters below the ocean surface. Hydrothermal vents create sulfide deposits containing precious metals such as silver, gold, copper, manganese, cobalt and zinc. The deposits are extracted using hydraulic pumps or bucket systems that bring the ore to the surface for processing.

Una vez que el mineral es extraído tiene que ser procesado de acuerdo a ciertos protocolos analizados durante años. La ciencia que estudia dicho proceso es la metalurgia extractiva, que es un área de la metalurgia que estudia la extracción de los metales preciosos de los minerales mediante medios químicos, mecánicos o electrolíticos.[38]​ Uno de los estudios de dicha ciencia es el procesamiento de minerales, que analiza los medios mecánicos de trituración, molienda y lavado, que permite la separación de los metales con valor económico de la ganga. Como la gran mayoría de los metales están presentes en los minerales de óxido y sulfuros, es necesario procesarlos mediante la fundición "Fundición (metalurgia)") o por medio de la reducción electrolítica. La ciencia que combina todos estos procesos ya sea la minería, la metalurgia extractiva y las ciencias geológicas, además de la economía del yacimiento y los posibles daños medioambientales, se denomina geometalurgia.[39]​.

Productive circuit

The production circuit, or also called the production process, is defined as the stages through which a mineral undergoes until it becomes a marketable product. Below is a list of the main processes that are applied to a metallic mineral. Of course, this list is a general one, since depending on the metal some threads may be included.

Al igual que muchas de las actividades humanas la minería produce serios problemas al medio ambiente, debido a sus diversos procesos mineros y químicos. Estos efectos pueden incluir erosión, formación de dolinas "Dolina (geología)"), pérdida de la biodiversidad, contaminación de las aguas subterráneas y superficiales, como también contaminación del suelo. En algunos casos, se incluye como factor adicional la deforestación en torno a la mina, con el objetivo de crear espacio suficiente para las instalaciones necesarias para su funcionamiento y el almacenamiento de residuos. Por su parte, la contaminación resultante de las fugas de sustancias químicas afecta directamente a la población local, si no se controla adecuadamente.[40]​ Un caso extremo de daño ambiental es el incendio en la mina de carbón de Centralia en Pensilvania, que desde 1962 arde por sus túneles ubicados debajo de la localidad estadounidense.[41]​.

En muchos países, las compañías mineras están obligadas a seguir y cumplir estrictos códigos de protección del medio ambiente con el fin de minimizar su impacto ambiental y evitar eventuales problemas a la comunidad adyacente. Estos códigos o reglamentos obligan a las mineras a realizar la evaluación de impacto ambiental, desarrollar planes de gestión ambiental, programar el cierre de la mina y elaborar monitoreos ambientales durante la operación y después del cierre. Por su parte, si las grandes compañías requieren buscar financiamiento internacional en instituciones como Equator Principles") y en la Corporación Financiera Internacional, deben cumplir otra serie de normas ambientales y, además, satisfacer los criterios de la inversión socialmente responsable.

Más allá de las exigencias establecidas por las instituciones financieras o por los organismos gubernamentales de cada país, con los años las grandes compañías mineras han autoregulado sus efectos al medio ambiente mediante una serie de códigos de conducta. En 2001, nueve de las grandes compañías crearon el Consejo Internacional de Minería y Metales") (ICMM, por sus siglas en inglés), cuyo objetivo es mitigar el daño al medio ambiente, reducir, reutilizar y reciclar los insumos, integrar en el concepto de mercado el desarrollo sustentable y contribuir a la conservación de la biodiversidad, entre otros puntos.[42]​ Actualmente, 23 compañías mineras y de metales en conjunto con 35 asociaciones mineras nacionales y regionales integran este consejo internacional. A su vez, algunas de ellas son miembros activos en la creación de políticas de ecoeficiencia de organizaciones como la Cámara de Comercio Internacional y el Consejo Empresarial Mundial para el Desarrollo Sostenible.[43]​.

Tailings contamination

One of the main elements of pollution generated by the mining industry is that caused by tailings, which are classified as sterile or mineralized waste, with high levels of acids and chemicals, and whose storage is an important part of the mine planning process. In simple terms, a tailings is the gangue or material that is not economically viable from the extractive process of the mining operation, the quantities of which vary depending on the metal to be extracted. For example, a mineral that contains 20% metal will produce about 4 tons of tailings, while if it has only 1% metal, its extraction could generate up to 99 tons of tailings.[44]​ In the case of gold mining, considered one of the highest gangue producers in the industry, only 5.3 grams of gold are obtained for each ton, that is, to achieve one ton of Au, about 200,000 tons of Au will be produced. tailings.[45]​.

To store the tailings, dams are built, which are engineering works made up of a retaining wall and a bucket, and which serve the same purpose as dams.[46] Until 2000, it was estimated that there were 3,500 dams in operation and that every year between two or three large dams and 35 smaller ones were created. Poor planning and construction can lead to severe risks for their environment, due to the failure of the retaining wall produced by the pressure of the tailings, the dragging of waste due to extensive rainfall, filtration of its waters to the surroundings and infiltration under the dam, lifting and dragging of fine material due to the wind, among others.[46]​ The collapse of a dam causes critical contamination in surface and underground waters, biodiversity, soil and surrounding populations due to the high concentrations of acid, mercury "Mercury (element)"), iron, arsenic and lead, among other chemicals typical of mineral processing.

Throughout history there have been serious accidents caused by the spill of tailings, for example, in 1965 and after an earthquake the dam of the El Soldado Mine collapsed, located in the commune of Nogales "Nogales (Chile)") in Chile, whose contamination spread for hundreds of kilometers, completely burying the El Cobre mining camp and causing the death of 200 people.[47]​ In 1996, in the Marcopper mine in On the Philippine island of Marinduque, 1.6 million cubic meters contaminated 27 kilometers of the banks of the Boac River and the coastal area. Its devastation meant the death of fish, river shrimp and pigs, the contamination of drinking water sources, the complete destruction of the Hinapulan barangay, the isolation of more than 20,000 people and the evacuation of a third of the villages in the province of Marinduque.[48]

For its part, on November 5, 2015, the worst tailings disaster in South America occurred when two dams at the Samarco Mineração S.A. mine, a company created by Vale S.A. and BHP Billiton, collapsed in the Bento Rodrigues subdistrict in the state of Minas Gerais in Brazil. In total, it was estimated that 55 million cubic meters of mud and iron ore waste killed the biodiversity of the Doce River, destroyed a town of 300 families, forced the suspension of water supplies to more than 250,000 people, left 15 dead and 12 missing, and left hundreds of millions of dollars in material and natural losses. Even, months later, it was confirmed that its waste reached Regencia beach in the state of Espírito Santo.[49][50]​.

La minería como industria ocurre en varios países del mundo, siendo Londres la capital mundial de esta actividad. La ciudad británica es la sede del principal mercado del mundo en transacción de metales no ferrosos y es la sede de las principales compañías mineras, tales como Rio Tinto Group, BHP Billiton y Anglo American. Otro mercado de importancia es el New York Mercantile Exchange, donde se contratan derivados financieros de algunos metales preciosos y productos energéticos como el petróleo y gas natural. Por último, la Bolsa de Shanghái está enfocada para aquellos países que exportan minerales a China, como por ejemplo las naciones situadas en las orillas del Océano Pacífico.[51]​ En el caso de los Estados Unidos la minería es considerada como una gran actividad financiera; sin embargo, está dominada por el carbón y la minería no metálica. No obstante, durante los últimos años diversos reglamentos han tratado de reducir la importancia de la actividad en el país.[52]​ En otros países anglosajones como Canadá y Australia, la minería desde hace décadas se ha convertido en parte significativa de la economía interna.

En 2002, la OCDE situó a Chile y Perú como los principales productores de minerales de Sudamérica y estimó que tenían un gran potencial económico durante los próximos años en dicho rubro.[53]​ Por su parte, la industria en África es una de las más importantes y a su vez emergentes, ya que a pesar de que su participación en la producción de cobre, plomo y zinc es relativamente menor, se estima que el continente posee un importante porcentaje de minerales del mundo, como por ejemplo el 40% de reservas de oro, el 60% de cobalto y el 90% de los minerales del grupo del platino.[54]​ En 2010, dos de las cuatro economías que más crecieron en el mundo son exportadores de minerales y a su vez africanas, Botsuana y República del Congo, mientras que las otras dos son exportadoras de petróleo.[55]​ En cuanto a los minerales de tierras raras, en 2013 China controlaba el 95% de la producción mundial de mencionados elementos.[56]​ Por su parte, Chile es el principal exportador de yodo con el 60% de la producción mundial y además, es el único productor global de nitratos o salitre.[57]​.

Mining classification

Each mineral-producing country uses various criteria to organize industry production and have a better understanding of its impact on the regional and national economy. The vast majority of countries use the criterion of the number of metric tons produced per year, although in some specific cases the capital of the mine, infrastructure or job creation is also included. Broadly speaking, the industry is classified into large, medium and small mining; However, in some countries such as Peru, a fourth classification is considered, artisanal mining.[58] Below are the characteristics of the three main divisions of mining and an example of the production figures required by the laws of Chile and Peru, considered by the OECD as the main mineral-producing countries in South America.

Mining companies

Mining companies are companies that carry out various activities to transform raw materials into specific products, whose competence depends on the production of extracted mineral and its quality and quantity.[60] Many of the large companies are multinational, private in nature and also with capital open to the public in international markets. However, there are certain public or state companies with a large market share, such as the Chilean Codelco and the Indian National Mineral Development Corporation.

For their part, mining companies are classified into five categories according to the extraction and commercialization of the respective resources. These are oil and gas, coal mining, metallic minerals, non-metallic minerals and quarries, and mining support activities.[61]​ Another way of classification is according to the net annual income earned by a company, classified as follows:[62]​.

In 2012, the services firm PwC made a list of the main mining companies worldwide, where it also highlighted the number of companies per country. In first place was Canada with nine companies, followed by England with seven and the United States with five.[55] It should be noted that BHP Billiton and Rio Tinto Group appear in both England and Australia, because they have capital from both countries. The same happens with Antofagasta plc, since it has capital from England and Chile.

Main mineral producers worldwide

In 2012, the United States Geological Survey (USGS) made a table with the largest gold, silver, copper and nickel producing countries worldwide. In turn, they were classified as developed, countries that have a track record in the field, emerging, countries that in recent decades have increased their participation worldwide, and developing, countries that have just begun large-scale activity. 16% nickel.[55]​.