Marcello M. Veiga

Clean artisanal gold mining: a utopian approach?

Artisanal and small-scale mining (ASM) provides an important source of livelihood for rural communities throughout the world. These activities are frequently accompanied by extensive environmental degradation and deplorable socio-economic conditions, both during operations and well after mining activities have ceased. As gold is easily sold and not influenced by the instability of local governments, it is the main mineral extracted by artisanal miners. Mercury (Hg) amalgamation is the preferred gold recovery method employed by artisanal gold miners and its misuse can result in serious health hazards for miners involved in gold extraction, as well as for surrounding community inhabitants, who may be exposed to mercury via the food chain. The rudimentary techniques characteristic of ASM result in a number of occupational hazards, other although most risks are primarily attributed to machinery accidents and ground failure, such as landslides and shaft collapses. Several technologies and methods commonly utilized by large-scale mining operations can be downsized to smaller scale operations. However, the likelihood that miners will adopt these large-scale methods, or those developed specifically for ASM, depends upon some key factors. For an artisanal miner, these factors include: (1) increased or comparable simplicity, (2) quick recovery of the economic mineral, and (3) demonstrated financial gain. Other practical aspects, such as the availability of materials (chemicals, steel rods, piping, generators, etc), capital and operating cost requirements and access to technical support, also influence acceptance of new techniques. This article will review four inter-related areas: first, the limitations and benefits, for ASM, of a number of specific technologies; second, the role of Processing Centers in education, information dissemination and provision of “clean” services; third, benefits and challenges associated with formalization of ASM activities; and fourth, the contribution of ASM to the development of sustainability of communities, primarily through diversification of livelihoods. The appropriate application of technologies, particularly given the diversity of ASM communities around the world, will also be explored.  2002 Elsevier Science Ltd. All rights reserved.

Socioeconomic Consequences of Mercury Use and Pollution

Abstract In the past, human activities often resulted in mercury releases to the biosphere with little consideration of undesirable consequences for the health of humans and wildlife. This paper outlines the pathways through which humans and wildlife are exposed to mercury. Fish consumption is the major route of exposure to methylmercury. Humans can also receive toxic doses of mercury through inhalation of elevated concentrations of gaseous elemental mercury. We propose that any effective strategy for reducing mercury exposures requires an examination of the complete life cycle of mercury. This paper examines the life cycle of mercury from a global perspective and then identifies several approaches to measuring the benefits of reducing mercury exposure, policy options for reducing Hg emissions, possible exposure reduction mechanisms, and issues associated with mercury risk assessment and communication for different populations.

Mercury contamination from artisanal gold mining in Antioquia, Colombia: The world's highest per capita mercury pollution.

The artisanal gold mining sector in Colombia has 200,000 miners officially producing 30tonnes Au/a. In the Northeast of the Department of Antioquia, there are 17 mining towns and between 15,000 and 30,000 artisanal gold miners. Guerrillas and paramilitary activities in the rural areas of Antioquia pushed miners to bring their gold ores to the towns to be processed in Processing Centers or entables. These Centers operate in the urban areas amalgamating the whole ore, i.e. without previous concentration, and later burn gold amalgam without any filtering/condensing system. Based on mercury mass balance in 15 entables, 50% of the mercury added to small ball mills (cocos) is lost: 46% with tailings and 4% when amalgam is burned. In just 5 cities of Antioquia, with a total of 150,000 inhabitants: Segovia, Remedios, Zaragoza, El Bagre, and Nechí, there are 323 entables producing 10-20tonnes Au/a. Considering the average levels of mercury consumption estimated by mass balance and interviews of entables owners, the mercury consumed (and lost) in these 5 municipalities must be around 93tonnes/a. Urban air mercury levels range from 300ng Hg/m(3) (background) to 1million ng Hg/m(3) (inside gold shops) with 10,000ng Hg/m(3) being common in residential areas. The WHO limit for public exposure is 1000ng/m(3). The total mercury release/emissions to the Colombian environment can be as high as 150tonnes/a giving this country the shameful first position as the worlds largest mercury polluter per capita from artisanal gold mining. One necessary government intervention is to cut the supply of mercury to the entables. In 2009, eleven companies in Colombia legally imported 130tonnes of metallic mercury, much of it flowing to artisanal gold mines. Entables must be removed from urban centers and technical assistance is badly needed to improve their technology and reduce emissions.

World emissions of mercury from artisanal and small scale gold mining

We estimate mercury releases from artisanal and small scale gold mining (ASGM) based on available data about mercury and gold exports and imports by country and from field reports from the countries known to have active ASGM communities. The quality of the estimates ranges from reasonable to poor across the countries. This paper aims to give a first order estimate of the amount and location of mercury being released into the environment globally by ASGM, to motivate stakeholders to improve the quality of these estimates, to illustrate the linkages between global mercury trade and its use in ASGM, and the fourth objective is to provide a practical outline of the options available for reducing mercury use in ASGM. We estimate that artisanal and small scale gold mining releases between 640 to 1350 Mg of mercury per annum into the environment, averaging 1000 Mg yr-1, from at least 70 countries. 350 Mg yr-1 of this are directly emitted to the atmosphere while the remainder (650 Mg yr-1) are released into the hydrosphere (rivers, lakes, soils, tailings). However, a significant but unknown portion of the amount released into the hydrosphere is later emitted to the atmosphere when it volatilizes (latent emissions). Considering that ASGM is growing, latent emissions conservatively amount to at least 50 Mg yr-1 bringing the total emission of mercury to the atmosphere from ASGM to 400 Mg yr-1. This estimate of emission to the atmosphere differs from the previous one provided in the 2002 UNEP Global Mercury Assessment both in terms of its magnitude (400 Mg yr-1, versus 300 Mg yr-1) and in the way the estimate has been made. The current estimate is based on a better understanding of ASGM and on a wider variety of information sources, more field evidence, better extrapolation methods, and independent testing by analysis of official trade data.

Abandoned artisanal gold mines in the Brazilian Amazon: A legacy of mercury pollution

The modern gold rush in the Brazilian Amazon attracted millions of people to become artisanal miners in order to escape complete social marginalization. The rudimentary nature of artisanal mining activities often generates a legacy of extensive environmental degradation, both during operations and well after mining activities have ceased. One of the most significant environmental impacts is derived from the use of mercury (Hg), which is illegal for use in gold amalgamation in Brazil, but continues to be the preferred method employed by artisanal gold miners. The general population is unaware of the capricious nature of mercury and artisanal mining activities. Moreover, individuals in positions of political or economic influence tend to be negatively biased towards artisanal mining and government policies do not effectively address the realities of these activities. Affected communities have consequently been ignored, and mistrust towards outside parties is high. Not surprisingly, miners are suspicious of and unlikely to employ externally derived solutions to reduce mercury emissions. This article reviews the use of mercury in artisanal mining and highlights the role miners, governments and non-governmental organizations (NGOs) have played in communicating facts, perpetuating myths and deriving solutions for mercury pollution. This article also raises some key concerns that must be addressed to understand the behaviour of mercury in the environment and identifies solutions for problems facing communities where artisanal gold mining operations have been abandoned.

Building Capacity in Small-Scale Mining Communities: Health, Ecosystem Sustainability, and the Global Mercury Project

The Global Mercury Project (GMP) is an initiative of the United Nations in collaboration with numerous government and nongovernment organizations to promote knowledge and capacity building on the links between small-scale gold mining practices and health, ecosystem, and social factors, and to implement interventions that reduce mercury pollution and exposure caused by mining activities in developing countries. Knowledge regarding the use of mercury and the dynamics of complex environmental, health, socioeconomic, and cultural conditions in and surrounding small-scale mining sites is particularly needed for the purpose of developing appropriate community-based measures to reduce mercury-related problems. GMP strategies aim to build upon local knowledge and practices to train miners on the use of cleaner and affordable technologies of mining and mineral processing in order to minimize negative impacts. The initiative is especially proactive in facilitating transdisciplinary and participatory models of community interaction, involving local, regional, and international stakeholders in each of the strategy design, community assessment, and community intervention phases. The six participating countries are Brazil, Indonesia, Lao People’s Democratic Republic, Sudan, Tanzania, and Zimbabwe. This article outlines GMP’s objectives and scope of activities and also highlights achievements, challenges, and opportunities for future development.

An estimation of the artisanal small-scale production of gold in the world.

The increase in gold price of over 400% between 2002 and 2012, due to a shift towards safe investments in a period of crisis in the global economy, created a rapid increase in gold production. A response to this shift in production was observed for artisanal and small-scale mining (ASM) units in remote locations of the world, but this phenomenon has not been quantified yet. The work presented here was done to provide a quantitative tool for estimation of the gold (Au) produced by ASM and the population of workers involved in the production process, and assessment of mercury (Hg) consumed. The following hypotheses were addressed: i) It is possible to estimate, on first approximation, the amount of Au production in the world by artisanal mining; ii) Au production by artisanal mining varies by country and continent and iii) Hg consumption due to ASM can be correlated with the methods applied in the different countries and continents for the production of Au. To do this we estimated the number of miners, calculated the change in Au price and production and then applied an adjustment factor to calculate Hg production by country and continent. The amount of Au produced depends on technology of the miners by continents (highest in South America, medium in Asia and Central America, and lowest in Africa), and the geologic setting (not investigated here). The results of the estimation show that, as of 2011, over 16 million Artisanal Miners, in the world, were involved in gold extraction (mining or treatment), producing between 380 and 450 t of gold per year, with clear global behavior between the continents in terms of recovery efficiency, confirmed by data on Hg release that is higher in countries with lower technology.

Mercury Reduction in Munhena, Mozambique: Homemade Solutions and the Social Context for Change

Abstract The health and environmental impacts of artisanal gold mining are of growing concern in Munhena, Mozambique, where more than 12,000 people are involved in such activities. Gold is extracted using mercury amalgamation, posing a considerable threat to human and environmental health. A pilot project ascertained the feasibility of reducing mercury use and emissions by promoting control measures utilizing local resources. Retorts were fabricated with local materials. Training workshops introduced the homemade retorts, and a portable mercury monitor revealed effective mercury reduction. Barriers to widespread technology adoption include poverty, lack of knowledge and trust, and the free supply of mercury from private gold buyers. Homemade retorts are inexpensive and effective, and miners could benefit by building community amalgamation centers. The government could play a greater role in gold purchasing to reduce mercury pollution.

Using Performance Indicators to Evaluate an Environmental Education Program in Artisanal Gold Mining Communities in the Brazilian Amazon

Abstract The Tapajos River Basin in the Brazilian Amazon is the location of one of the largest concentrations of artisanal and small-scale miners in the world. Today, 40 000 miners produce 8 t of gold annum−1 and at least double this amount of mercury is released into the environment. This region was selected under the Global Mercury Project, a United Nations program that aims to reduce the environmental and health impacts caused by mercury through the application of cleaner technologies and increased awareness. A group of educators provided support to miners, training 4200 people in 141 mining locations. The effectiveness of this training was evaluated based on 20 performance indicators. After 120 days of training, an absolute improvement of approximately 29% had been achieved. As a result of this training, it is estimated that annual mercury emissions in Tapajos have been reduced by 1762 kg or around 10% of the total mercury released in the region.

Mercury and Artisanal Mining in China

Throughout the world, the growth of artisanal or small-scale mining has resulted in serious mercury pollution issues. While these problems are well studied in much of the world, little has been written about the state of affairs in the Peoples Republic of China. It is vital to understand how the situation has evolved in China to determine if Chinas methods of dealing with these environmental and health problems could be applicable to other parts of the world, or if techniques and solutions developed outside of China could be used by the Chinese. Artisanal mining employs about 6 million people in China, who often work in deadly conditions, and contributes to environmental degradation on a huge scale. Chinese artisanal mercury, coal, and gold miners emit hundreds of tonnes of mercury into the environment annually. Artisanal gold miners often use muller mills, which amalgamate whole ores and thus increase mercury contamination in the tailings; more than 14 parts mercury can be lost per part of gold recovered. Many operations do not use retorts, leading to mercury vapor contamination. In 1997, artisanal and small-scale mining emitted approximately 381 tonnes of mercury, of which 226 tonnes were due to gold mining. The implementation of simple measures, such as providing communities with accessible education regarding environmental issues, encouraging the use of retorts, and discouraging the amalgamation of whole ores, would help to mitigate these problems.