La Oroya metallurgical complex: Peru

La Oroya metallurgical complex: Peru

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By Ing. Agustín Mamani Mayta

In La Oroya, weather conditions play an important role in air quality for the city and its surroundings; One of the most salient problems is the location of the Oroya Antigua with more than thirteen thousand inhabitants just three hundred meters from the Foundry and separated only by the Mantaro River. Pollution will persist for unpredictable times.

"La Oroya is considered the Metallurgical Capital of South America and is the fifth most polluted city on Earth"

1.- Summary

The metallurgical complex of La Oroya, located in the central region of Peru, since 1922, has been processing polymetallic concentrates in the copper, lead and zinc circuits in an integral way, and produces 20 products between metals and by-products; being on earth one of the four polymetallic foundries that process this type of materials. This strength and added the rise in the price of metals, makes their operation more competitive, with the inherent consequences of environmental pollution by the fumes emanating from the main chimney and fugitive emissions.

2.- Introduction

It is well known that the operations and processes used in foundries and refineries are technologies that come from the 1920s or so; With these technologies, Premium metals are produced, from polymetallic concentrates.

By the very nature of their technology they are exclusively designed to process concentrate and dirty minerals. On earth there are only very few metallurgical companies dedicated to treating dirty concentrates (Dowa Mining Ltda., In Japan; Hoboken from Union Miniere, in Belgium; Ronskar from Boliden Minerals, in Sweden and La Oroya from Doe Run Peru SRL, in Peru ), because by treating clean concentrates, the company would go bankrupt. Modern competition is strong, where the maquilas are regulated (cost of processing concentrates into intermediate or final products).

The metallurgical complex of La Oroya located at an altitude of 3,750 meters above sea level, unlike others that exist on land, is the only one that processes copper, lead and zinc concentrates through differentiated procedures, which are closely linked by transfers, miscellaneous and cleaning that are manipulated, according to their analysis in subsequent processes, as the case may be in the relevant circuits. In other words, in this network of dependent relationships between the three circuits, nothing is lost, everything has commercial value.

It is important to differentiate what we call dirty concentrates; They are those where the impurities exceed the limits; To cite an example, arsenic in copper or lead concentrates that are above 1.0%; lead in the copper circuit or vice versa; zinc in copper and lead concentrates; antimony above 0.5%; and bismuth above 0.15%; These parameters are regulated in the supply and demand market at an international level.

The moisture content in the raw material also has negative implications, both for the seller and the buyer. The excess of water in the material that exceeds for example 10% is penalized by the surplus, by handling and greater consumption of fuel in its drying, among other factors, which are considered within the operations and the process.

3.- Strengths and opportunities of the metallurgical complex

The competitive advantages of the metallurgical complex that make it highly profitable, can be indicated:

• Maquilas and refining costs are differentiated by processing polymetallic concentrates with high impurities.

• The so-called polluting elements "impurities" of the material to be processed, depending on the material and the circuit to be processed (circuits of: copper, lead and zinc), are penalized in accordance with the international supply and demand market that regulates them (LME , COMEX, LONDON, etc.). These elements give the company considerable marginal cost, because these impurities are recovered in the main process and treated through a differentiated process, thus obtaining by-products that have more value than the main metals (tellurium, selenium, indium, bismuth, etc. .).

• When the buyer-seller negotiation is carried out, not all the metallic content of a payable item is paid at 100% of the fine content, but the losses inherent to the process are considered, which fluctuate between 0.5% and 3.0% depending on In the smelting or refining stage, this negotiation mechanism is called “recovery”.

Due to their operational complexity, these losses in spills, gases, metallic vapors, fumes, etc., present in the pyrometallurgical and hydrometallurgical processes are recovered, by a) the particulate materials with heavy metals present in the metallurgical fumes in the Cottrells, Bag systems Houses, Scrubbers, except for those issued by fugitive emissions; and b) spills, leaks, etc., through continuous and constant cleaning and transferred according to their physicochemical analysis to the metal or by-product production processes.

• Within the original Environmental Management and Adaptation Program (PAMA) prepared by the Centromín Peru S.A. administration. and duly approved by the Ministry of Energy and Mines, the project for the abandonment of "zinc ferrite deposits", stored in Huanchan and within the Smelter facilities since the administration of Cerro de Pasco Corporation (since 1952, about 1.5 million tons have been accumulated). Due to its high value in metal content "zinc, lead, copper, manganese, silver, etc." (whose valuation is above US $ 230 million). The Doe Run Perú SRL administration through Directorial Resolution No. 283-2001-EM / DGAA (09.05.2201) manages the transfer of said project for its administration. It builds a modern flotation plant for the processing of zinc ferrites and their respective commercialization, obtaining an advance sale with the company Trafigura Cormin for 40 million US dollars and with which it supports as economic support for the expansion of the PAMA until 2009 ( El Comercio newspaper, December, 2005).

The operation of the metallurgical complex, from the Cerro de Pasco Corporation, Centromin Peru S.A. company, to the current administration; economically and financially, it was and will always be profitable.

In current circumstances, with the rise in metals, it is a panacea for the company Doe Run Peru SRL, a subsidiary of the Doe Run Company based in Missouri, a member of the transnational company Renco Group Inc., whose largest shareholder is Mr. Ira Rennert , presenting the propitious conditions for the fulfillment of the Program of Adequacy and Environmental Management "PAMA" and the consequent modernization of the complex.

4.- Weaknesses and risks of the metallurgical complex

The metallurgical complex also presents weaknesses and threats that with an ecosystem approach lead to corporate analysis and search for progressive and mediated solutions in some and immediate in others:

• The company Doe Run Peru SRL, administrator of the metallurgical complex, is not a mining company that produces concentrates, minerals, etc., its facilities are properly designed to process raw materials from different sources and varied concentrations of impurities and valuable metals and convert them into metals and by-products. Concentrates and minerals are purchased from the national market between 60% and 80%, and the rest is bought from the international market, depending largely on the availability of raw materials in the market, such as Spot purchases or contracts for three, four, five years, etc. The acquisition in quantity and quality of materials that enter the Peruvian territory, from countries where coincidentally they cannot be treated as they are prohibited by their environmental regulations, always remains a question. Therefore, it is important to know the type of materials that enter through an insightful characterization by the public and private organizations responsible for these activities for the benefit of the health of the population and workers, the local and regional ecosystem.

• Another worrying question is the heavy vehicular traffic from Lima, capital of Peru to Oroya (at a distance of 175 kilometers) that must be declared in emergency. Trucks loaded with concentrates, minerals, and other raw materials circulate daily from Callao and Lima to La Oroya; and they return loaded with intermediate products produced in the metallurgical complex (eleven metals and nine by-products), available to satisfy the national demand in a small proportion and the rest to the international market, via Callao. Concentrates also arrive, fluxes from other regions via Cerro de Pasco, Huancayo to La Oroya. It is worth mentioning that La Oroya, due to its geographical location, is an obligatory passage for the central region and the central jungle, both by road and railroad.

• The technology used in the foundry continues to maintain the same processes since 1922 for copper, 1928 for lead and 1952 for zinc, as only additional modifications were made: Thus, during the administration of the company Centromin Perú SA, the oxygen plant, in 1994; the new sintering plant, in 1983; modifications in the metallurgical indices of the copper melting bed and the Oxy fuel project, in 1994. During the administration of the company Doe Run Peru SRL, the implementation of tuyeres control of the lead furnaces, construction of the short rotary furnace for treat recirculating materials with high impurities, treatment plant for zinc ferrites accumulated in the Huanchan deposits.

Peru's environmental regulations are not in accordance with international standards, as shown in the following table from the World Bank:

Table N ° 1 - World Bank

PollutantPrimary Lead and Zinc Foundries
mg / m3
Copper primary smelters
mg / m3
Ministerial Resolution 315-96-EM / VMM
mg / m3
Arsênico, As0,100,5025
Cádmio, Cd0,050,05
Sulfur Dioxide, SO24001000
Lead, Pb0,500,2025
Particulate Material, PM2020100

Source: World Bank; Presentation by Renan Poveda; Lime; 12.04.2005

Under these conditions, compliance with the LMP (Maximum Permissible Limit), therefore the "ECA" air quality standard, can be achieved relatively within the environmental standards defined in our Country, which is very far from the international standards, defined by WHO, CDC, OSHA, EPA for this type of activities, leaving as a question: "who guarantees that these LMP are adequately complied with", due to the technology used there will always be episodes harmful to the environment and human health.

• As the metallurgical complex is designed to process concentrates and polymetallic minerals (there is no characterization of these chemical elements in concentrates, minerals, bulk, fluxes and others). By technical deduction, the presence of metallic and non-metallic components can be demonstrated (in percentages, parts per million, parts per billion), defined in the periodic table of elements present in raw materials; that within metallurgical operations have little or minimal impact due to weight content. Of which, a part, during the pyrometallurgical, hydrometallurgical and electrowinning processes are passivated and / or removed from the process as complexes, oxides, sulfides, etc., for processing in another stage of the copper and lead circuit mainly, and, for another part, as slags that are transported by cable car to Huanchan .; Rather, how would the presence of metals that is properly called “Toxic Cocktail” be explained that are not produced in the metallurgical complex, but are in the environment and in the human body, as indicated in Table N ° 1.

Table N ° 2 - Combined exposure of various toxic elements.

Geometric means (µg / L)
La OroyaConceptionUS population
Berileo ***
Molybdenum *53,5873,3745,00
Antimony *4,021,560,134

* Statistically significant between La Oroya and Concepción (p <0.05)
** Below detection level (0.009 µg / L)
*** 95% sample below detection level (0.072 µg / L)

Source: University of San Luis, USA; Archbishopric of Huancayo; Study on environmental pollution in the homes of La Oroya and Concepción and its effects on the health of its residents; December 2005

• One risk that the metallurgical complex will have to face is with respect to contamination. Since 1922 the air, water and soil are being polluted and there is an environmental liability with shared responsibility between the state (Centromin Peru S.A.) and Doe Run Peru SRL; that technically, socially, economically and financially it will be impossible to remedy, due to lack of resources to remedy more than 14 thousand hectares of land directly affected by metallurgy. The state created the company Activos Mineros with a social capital (trust) of 22 million dollars and requires 45 million dollars to solve the environmental liabilities of La Oroya and other mining camps and assume projects that were under the administration of Centromin Peru SA ( El Comercio newspaper, February 3, 2007). In La Oroya, with the expansion of the PAMA, a legal vacuum remained to be defined, regarding the remediation of the soils and areas affected by the smelter (Centromin Perú SA assumed its responsibility for remediation, after the company Doe Run Perú SRL de compliance with the PAMA as of January 2007 and has reduced the emission of pollutants into the environment). Leachates, products of the reaction of water with particulate matter associated with heavy metals and that have accumulated since 1922 (85 years) in the soil, would be affecting the groundwater table and altering the physicochemical and bacteriological composition of the groundwater and surface water that consumes the population.

• Although the process is continuous during the process from the preparation of the melting beds "beds" (mixture of concentrates, minerals, fluxes, transfers, miscellaneous, cleaning) for copper, lead and silica with percentages of fine content (beds copper around 18 to 19% copper; lead beds with 39 to 40% lead) and other payable or penalisable elements that are present in these, to reach refined copper or lead it takes approximately between 28 and 15 days, there are and there will always be fugitive emissions due to the process itself, this no one can stop or remedy, prevent if.

• As well as in the metallurgical complex, quality Metals and By-products are obtained that are recognized worldwide thanks to ancient technology and the quality, wisdom and efficiency of existing human resources, presents significant environmental problems due to air, water and soil contamination Either by the discharges of liquid effluents into bodies of water, gas emissions and particulate matter associated with heavy metals and sulfur dioxide into the environment that is affecting flora and fauna.

Table N ° 3 - Emissions of pollutants into the atmosphere by the metallurgical complex - 1922 - 2002

PollutantDownloaded by Cerro de Pasco Corporation
T * 1000
Downloaded by the company Centromin Perú S.A.
1974 – 1997
t * 1000
Downloaded by the company Doe Run Peru SRL
1997 – 2002
t * 1000
Total downloaded
1922 – 2002
t * 1000
Lead, Pb95,326,33,2124,8
Arsenic, As190,618,32,0210,9
Particulate matter, PM869,8100,312,4982,5
Sulfur dioxide, S0213 690,68 430,81 761,323 882,7

Source: MEM; SVS Ingenieros y Golder Associates Brasil Ltda .; Special examination of the revegetation project of areas affected by smoke from Centromin Peru S.A.'s PAMA in La Oroya; August 2003; Table 6.5; P. 51

• For more sulfuric acid plants that are built in the zinc, lead and copper circuits, they will not be able to eliminate the emissions of sulfur such as sulfur dioxide existing in the metallurgical fumes to the environment. According to studies carried out by the company of 100% (1 015 tons of sulfur dioxide), with the repowering of the sulfuric acid plant in the zinc circuit and the construction of sulfuric acid plants in the Lead circuits (Sintering Plant ) and copper (Reverber plants and converters) will only reduce approximately 79% of sulfur emissions to the environment (Doe Run Peru SRL, expansion of PAMA 2007-2009), the rest (21%) will continue to emanate, with the danger that These discharged particulate materials are below PM10 and PM2.5, with serious risk for the surrounding population (in other countries, international organizations are already considering PM 1).

Table N ° 4 - Loss of pollutants to the environment

Main fireplace
ton. per day
Fugitive emissions
ton. per day
ton. per day
Sulfur dioxide925.0090,001 015,00

Source: Doe Run Peru srl operating plan, 2004 – 2011

The sulfuric acid produced in the three plants with a production capacity of 395,000 tons per year, the company will have a domestic and foreign market for its commercialization; Bearing in mind that the Southern Peru Copper Corporation in its smelter in Ilo has a sulfuric acid plant with modern technology, with a production capacity of 750,000 tons per year and a recovery efficiency of 94% and with a market already defined (Southern Peru Copper Corporation, PAMA) It is necessary to consider two aspects: a) sulfuric acid within Peruvian regulations is considered a controlled chemical product (IQF) because it has an impact on the production of cocaine, and, b) its commercialization in the domestic market As international it presents risks, as it is, its handling and land transport "tank cars" (railway line and road), as it is a product of high corrosivity and toxicity; If not, let's review within the specialized literature "the safety data sheet (MSDS in English) of sulfuric acid".

One thing is certain, that the pollution will persist for unpredictable times, due to the emanation of gases, fumes, vapors and particulate matter emitted by the main chimney and by the events of fugitive emissions; the mitigation of environmental liabilities, and if to these assets, we add pollution from urban and industrial solid waste, visual, acoustic, light and electromagnetic pollution.

• La Oroya for its strategic location, with a rugged and sloping topography, meteorological conditions play an important role in air quality for the city and its surroundings; One of the most salient problems is the location of the Oroya Antigua with more than thirteen thousand inhabitants just three hundred meters from the Foundry and separated only by the Mantaro River, where fugitive emissions converge caused by the pyrometallurgical processes of the Foundry, which are difficult to quantify by its irregularity and rapid dispersion in the environment and its mobility towards the city at ground level. According to studies carried out by specialized institutions hired by the company Doe Run Peru SRL, they conclude that the impact of fugitive emissions is eight times greater than the impact of those emanating from the main chimney for the same heavy metals (McVehil, Monnet and associates). According to studies carried out by DIGESA, by specialized entities for CONAM, an agreement between the University of San Luis-Missouri and the Archdiocese of Huancayo and CDC, the contamination is found in the city of Huancayo (distance 140 km). In addition, there is an inconsistency between the increase in the production of metals and by-products, the reduction of emissions of particulate materials associated with heavy metals from the main chimney and fugitive emissions, air quality and the levels of intoxication of the population with heavy metals. (SVS engineers SA, Golder Associates Brasil Ltda.) That will have to be validated by means of a pertinent inspection and monitoring.

Thermal inversions, a climatic process that occurs when the upper layer of the atmosphere stays hotter than the lower layer (degree of cooling of the soil surface), causing gases, combustion fumes, vapors, metallic fumes and particulate matter with heavy metals that are released into the environment by the main chimney and fugitive emissions descend and are concentrated in the city and its surroundings, between 8.00 am and 11.00 a.m. with negative effects on human health and biodiversity. According to the evaluations made by Gesta Zonal Aire de La Oroya of the available information, approximately 93% of the days of the year were found to have the presence of thermal inversion to a greater or lesser degree of periodicity (acute and chronic episodes in relation to the time of residence): The National Environmental Council "CONAM" approved the plan to clean the air in La Oroya, based on the document "baseline diagnosis" prepared by the Gesta Zonal del Aire, the Ministry of Health being responsible for the implementation of Alert states.

• To date, the Foundry dispenses a main chimney (167.75 meters high) as the only source emitting metallurgical and constituent fumes into the environment; that emits approximately 35,400 cubic meters per minute of combustion fumes, a mixture of gases, vapors, metallic fumes and particulate matter with heavy metals. According to the company, to date, around 5,000 kilos of particulate material are being emitted into the environment (lack of supervision and validation by a specialized company with the participation of civil society), at a height of 129.63 meters above the The chimney has an automatic dust loss sampler installed, it dates from the modernization of the main chimney, to date more than 66 years have passed without being replaced by a modern one like the other five air quality monitoring stations o implementation of a state-of-the-art sampler that provides the required information in real time; what certainty will the data provided by that old sampler have. Today, modern technology allows the availability of information in real time, using satellite monitoring models, implementing the telemetry system for the control of emissions to the environment by the main chimney and fugitive emissions and preventive actions to avoid chronic episodes.

• The company states in its different communication media that they eliminated and / or reduced liquid emissions to the environment, as is the case of discharges to the Yauli River and the Mantaro River; solid emissions such as the washing of heavy and light cargo means of transport; Experience shows us that there is no technology or effective process, it always presents failures at any moment or unforeseeable circumstance, because there is nothing perfect; contingency plans will be effective to be mentioned when there is a disaster in the pipelines, bag houses, chimneys, structures, etc.

5. Conclusions

• It is important to carry out corporate and transparent actions with the participation of the authorities, private companies and civil society in the monitoring of metallurgical operations and control of the progress of the PAMA according to the schedule of investments committed to the Peruvian state by the company and the citizen participation in the post PAMA

• More scientific studies should be carried out with the participation of private companies and other national and international institutions specialized in the matter, to determine the toxicokinetics and toxicodynamics of the elements present in the environment; that have synergistic or antagonistic actions; It is only giving priority to the element lead, passing to second order sulfur dioxide, cadmium, arsenic, mercury, bismuth, antimony, and other heavy metals that pose risks to human health, flora and fauna.

• It is important to know the quantity and quality of the raw material processed in the metallurgical complex with its respective characterization; likewise, the characterization of the chemical elements present in the combustion fumes, gas mixtures, vapors, metallic fumes and particulate matter with heavy metals that are emitted by the main chimney and fugitive emissions.

There is much to comment, it only remains to hope that the private company Doe Run Peru SRL in accordance with its business philosophy "achieve international quality standards" and "work with public consent" will comply with its commitments to the Peruvian state, honoring its word to the Oroon population and the central region, leaving aside the assistance inherent to ancient mining, bearing in mind that modern mining advocates a joint work between the company, the state and the population committed to pollution.

6.- Bibliography

1. Alfaro A .; Lead Pollution in Callao, Peru; June 2006.
2. Archbishopric of Huancayo, Saint Louis University-United States; Study on environmental pollution in the homes of La Oroya and Concepción and its effects on the health of their residents, Report of first biological results; December 2005.
3. Balvin D., Ames E .; Gaps in mining policy to protect the health of people in the area of ​​influence of mining-metallurgical activities. Preliminary document; Lima, June 2003.
4. Blacksmith Insititute; Top 10 polluted sites - 2006 (The 10 most polluted places), Annual Report 2006
5. CDC; Development of a comprehensive intervention plan to reduce exposure to Lead and other pollutants in the La Oroya mining center, Peru; Spanish version; August 2005.
6. Cederstav A, Barandiaran A; La Oroya does not wait; SPDA-AIDA; September 2002.
7. Centromin Perú S.A .; Environmental Adaptation and Management Program "PAMA" - La Oroya Metallurgical Complex; December 1996.
8. College of Engineers of Peru; La Oroya Metallurgical Complex and its future investments; Metallurgy, materials and steel magazine, N ° 2; September 2004.
9. CONAM, Plan to clean the air of La Oroya, August 2006.
10. Congress of the Republic, Commission for the environment and ecology; Final report of the investigative subcommittee on compliance with the PAMAs and EIAs of the mining companies, 2003.
11. Cornejo A, Gottesfeld P .; Indoor lead levels, La Oroya- Peru; October 2004.
12. DIGESA; Study of Lead in blood in a selected population of La Oroya, November 1999.
13. DIGESA; Study of dispersion of heavy metals in samples of soil, dust, water and wild vegetation in the urban area and dressing rooms of La Oroya-Junín; August 2001.
14. Doe Run Peru SRL; PAMA for the La Oroya Metallurgical Complex, Period 2004-2001; February 2004.
15. Doe Run Peru SRL; Study of lead levels in blood in La Oroya, July 2001.
16. EPA; Measures imposed by the United States Environmental Protection Agency (EPA) to mitigate the impacts of lead contamination in the city of Herculaneum - Missouri; December 2000.
17. La Oroya Zonal Air Gesture; Baseline diagnosis La Oroya; 2004.
18. Integral Consulting, Inc .; Report on the study of risk to human health, La Oroya Metallurgical Complex, December 2005.
19. McVehil-Monnett Associates, Inc; Air quality dispersion modeling for the study of risks to human health; La Oroya Metallurgical Complex; September 2005.
20. Quijandría J., MEM; Program of Adaptation and Environmental Management PAMA of the La Oroya Smelter, Exhibition in the Congress of the Republic; April 2004.
21. SVS Ingenieros S.A., Golder Associates Brasil Ltda .; Special examination of the project for revegetation of areas affected by smoke from Centromin Peru S.A.'s PAMA. in La Oroya; August 2003.
22. SENES Consultants Limited; Critical review of the Environmental Adequacy and Management Program (PAMA) of the Doe Run Smelter in La Oroya, Peru; final report; November 2003.
23. Ugarte, J .; Study of the areas affected by smoke in La Oroya; nineteen ninety six.
24. UNES, Evaluation of the quality of air, water and soils in the Province of Yauli La Oroya, years 2001, 2002, 2203, 2004 and 2005.

* Agustín Mamani Mayta
Chemical Engineer - Master's Degree in Environmental Management - Diploma in air quality. Former Councilor of the Provincial Municipality of Yaul, La Oroya



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    the quality is normal, I thought it would be worse, but I was wrong and I'm glad about it)

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  4. Des


  5. Hien

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