Cyanidation of mercury-rich tailings in artisanal and small-scale gold mining: identifying strategies to manage environmental risks in Southern Ecuador

In many countries, such as Brazil, Colombia, Ecuador, Indonesia, Venezuela and Zimbabwe, amalgamated tailings are leached with cyanide to recover remaining gold. This paper describes a recently completed study conducted at seven gold processing centers in Portovelo-Zaruma, Southern Ecuador, which involved consultation with local miners. The objective of the study was to understand the behaviour of mercury (with a focus on mercury loss) in artisanal gold mining operations through the evaluation of two cyanidation processes (Merrill-Crowe and Carbon-in-pulp), using a participatory approach. In order to assess the kinetics of mercury dissolution in cyanide, a bottle roll test was conducted in the laboratory. In the Merrill-Crowe cyanidation process, an average of 24.2% of metallic mercury was determined to be trapped at the bottom of the agitation tanks; 33.1% of mercury is lost in association with solid material and 11.7% is lost in solution. Approximately 31.0% of mercury in solution is sent to the zinc precipitation cells from which 27.8% is precipitated on the zinc shavings, with 3.23% remaining in solution. The mercury precipitated on to the zinc is lost to the atmosphere when the shavings are burned at 900 °C. In the Carbon-in-pulp (CIP) leaching system, 11.2% of the mercury is lost with the solid tailings; 31.6% of the mercury is associated with fine particles in suspension and 50.8% is likely dissolved. About 2.68% is trapped at the bottom of the tank and 3.72% is absorbed by the activated carbon. The bottle roll test revealed that mercury dissolution is directly proportional to cyanide concentration. At 10 g/ton of cyanide, approximately 42% of mercury was leached, whereas all gold was solubilized. During this study, miners recognized the risk associated with the cyanidation of mercury-rich tailings, and were aware of how much mercury is discharged to local streams and to the atmosphere. The active participation of miners in this study has led to the strengthening of their knowledge and awareness of mercury contamination, and has enhanced their understanding of the nature of the problem, as well as the weaknesses and strengths of the system they operate.     

Strategies for reducing the environmental impact of reprocessing mercury-contaminated tailings in the artisanal and small-scale gold mining sector: insights from Tapajos River Basin,Brazil

Worldwide, the environmental impacts of artisanal and small-scale gold mining (ASGM) are extensive. Annual losses from mercury, which is used to amalgamate gold, are in the range of 1000 tonnes, and at advanced sites, there is the additional threat of cyanide contamination.Recent developments in The Brazilian Amazon, an area populated by 200,000 small-scale gold miners, have the potential to reduce these impacts considerably. In the locality of Garimpo Ouro Roxo, miners are presently using amalgamation and cyanidation in vat-leaching. Each cycle typically recovers 50% of the gold and lasts 20 days (per tank), consuming around 3300 kg NaCN/month. A new process has been developed and implemented in a pilot plant in this area, involving gravity concentration followed by cyanidation in a ball mill. Concentrate leaching is conducted with a PVC capsule filled with activated carbon inserted in the cyanide solution in the mill. The cycle takes less than 24 h and recovers up to 98% of the gold in the concentrate. The main advantages of wide adoption of this method, apart from a reduced gold recovery cycle and improved recovery, include possible phase out of amalgamation altogether, and marked reductions in cyanide consumption (from current 22,000 kg–980 kg annually).     

Reducing mercury pollution from artisanal gold mining in Munhena,Mozambique

Artisanal small-scale mining (ASM) is responsible for over 90% of gold production in Mozambique. In 2005, a 15-day pilot training project was held in the village of Munhena, a gold mining community. This intervention aimed at raising awareness related to the environmental and health impacts of mercury amalgamation and introduced alternative practices to reduce mercury release and exposure. In 2007, a 9-day evaluation of the pilot campaign was accomplished and knowledge in regards to mining methods, and the ASM government–community operating relations in Munhena were updated. Miners in Munhena are organized in an association of over 3000 members, work on a 25 year Government granted 143 ha concession and generate a substantial income (producing over 5 kg of gold per month). There remain, however, serious barriers towards sustainable community development. ASM associated environmental and health costs are high, as mercury continues to be used and lost to the environment, and cyanide will be introduced soon. The Government of Mozambique has laid the foundation for supporting this sector; however, resources are limited, and thus restrict ability to fully address these issues. Importantly, malaria and HIV/AIDS are not diagnosed and/or treated effectively within the community, and basic necessities are absent. This paper concludes with recommendations focused on enhancing the ASM sector in Mozambique, and overcoming barriers to sustainability in the community of Munhena.     

The role of artisanal and small-scale mining in China's economy

The last decades have seen increased international attention paid to a number of features of artisanal and small-scale mining (ASM). The beneficial roles of ASM in society and the economy in many countries, however, are often overlooked, while its negative impacts dominate official press coverage and scholarly publications of the sector. Through a review of the available literature and statistics, this paper works toward building a balanced picture of the overall role of ASM in China. First, the positive and negative impacts of ASM internationally are reviewed, followed by a short review of suggested and actual international policy responses. Then an examination of the impacts and role of ASM in China is undertaken. The authors argue that the contributions of ASM outweigh its negative impacts, but the central government needs to make more effort to regulate, guide and encourage the development of ASM and to create a sound environment for its operations.     

Mercury consumption and contamination of environment in gold mining in China

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A matter of approach: the retort's potential to reduce mercury consumption within small-scale gold mining settlements in Tanzania

The mercury-based gold extraction processes prevalent within small-scale mining are both efficient and harmful. While ensuring relatively high levels of gold recovery, they cause environmental and health problems for people living within mining settlements. This mercury consumption can be minimized by using a simple mercury recycling device known as a retort. While mining legislation in Tanzania dictates the use of retorts for gold recovery, virtually no miners use them, indicating the inadequacy of previous introduction attempts. During action research, retorts were introduced in two mining settlements through a thorough and participatory approach. Twenty miners were given retorts and their attitudes and receptiveness to them were studied. Of the recipients, 18 used the retorts over a period of five months, recycling 10 kilos of mercury. Less mercury was spilled into the environment and miners saved money normally spent on purchasing mercury. The findings have implications for the strategies of development interventions targeting mercury-instigated problems within small-scale gold mining.     

Nanomaterials for environmental burden reduction, waste treatment, and nonpoint source pollution control: a review

Nanomaterials are applicable in the areas of reduction of environmental burden, reduction/treatment of industrial and agricultural wastes, and nonpoint source (NPS) pollution control. First, environmental burden reduction involves green process and engineering, emissions control, desulfurization/denitrification of nonrenewable energy sources, and improvement of agriculture and food systems. Second, reduction/treatment of industrial and agricultural wastes involves converting wastes into products, groundwater remediation, adsorption, delaying photocatalysis, and nanomembranes. Third, NPS pollution control involves controlling water pollution. Nanomaterials alter physical properties on a nanoscale due to their high specific surface area to volume ratio. They are used as catalysts, adsorbents, membranes, and additives to increase activity and capability due to their high specific surface areas and nano-sized effects. Thus, nanomaterials are more effective at treating environmental wastes because they reduce the amount of material needed.     

Coastal flooding,climate change and environmental justice: identifying obstacles and incentives for adaptation in two metropolitan Boston Massachusetts communities

We explored the possible future impacts of increased coastal flooding due to sea level rise and the potential adaptation responses of two urban, environmental justice communities in the metropolitan Boston area of Massachusetts. East Boston is predominantly a residential area with some industrial and commercial activities, particularly along the coastal fringe. Everett, a city to the north of Boston, has a diversified industrial and commercial base. While these two communities have similar socioeconomic characteristics, they differ substantially in the extent to which residents would be impacted by increased coastal flooding. In East Boston, a large portion of residents would be flooded, while in Everett, it is the commercial/industrial districts that are primarily vulnerable. Through a series of workshops with residents in each community, we found that the target populations do not have an adaptation perspective or knowledge of any resources that could assist them in this challenge. Furthermore, they do not feel included in the planning processes within their communities. However, a common incentive for both communities was an intense commitment to their communities and an eagerness to learn more and become actively engaged in decisions regarding climate change adaptation. The lessons that can be applied to other studies include 1) images are powerful tools in communicating concepts, 2) understanding existing cultural knowledge and values in adaptation planning is essential to the planning process and 3) engaging local residents at the beginning of the process can create important educational opportunities and develop trust and consensus that is necessary for moving from concept to implementation.     

靖远矿区生态恢复与环境治理措施

靖远矿区经过了四十多年的开发建设 ,目前矿区生态遭到严重破坏 ,环境问题日益突出。由地下开采而引起的地表塌陷、矿井固体废物大量遗弃、高矿化度矿井水和瓦斯气体大量排放、土地沙化、植被减少 ,日益恶化的矿区生态环境质量 ,已严重制约和影响到本区经济发展和社会稳定 ,成为亟待解决的重大问题。本文通过分析 ,试图找出解决问题的办法     

Gold mining in Australia: linking historical trends and environmental and resource sustainability

The mining of gold has been and continues to be an important aspect of Australian industry. Gold mining moved quickly from fossicking and alluvial sources in the 1850's to hard rock mining. This paper presents, arguably for the first time, a detailed historical compilation of Australian gold mining production data. This data is then analysed in the context of sustainability, focussing particularly on mineral resource sustainability and the broader aspects of environmental impacts now commonly reported by some mining companies in annual sustainability performance reports. The key trends which are demonstrated by the data include a long-term decline in ore grade, increased open cut mining, substantive increases in tailings and waste rock production, as well as showing the impact of new technologies and economics on available gold resources. The available environmental data on material and energy inputs to and pollutant emissions from gold production is also presented, showing a clear sensitivity to ore grade. In terms of sustainability, these relationships raise significant issues such as increasing greenhouse footprint per unit gold produced, potential impacts on energy and water consumption, as well as overall gold resource sustainability. The paper presents a unique case study of the resource and environmental sustainability of the Australian gold mining sector with major implications for sustainability policy and reporting.     

Integrated environmental assessment and pollution prevention in Vietnam: the case of anthracite production

Using the concept of life cycle analysis, the whole life cycle of anthracite production in Vietnam was assessed and the environmental “hot-spots” were identified. These include (i) dust pollution at coal transfer points or piles in storage; (ii) noise pollution resulting from the usage of heavy equipment, and (iii) high volume of acid and turbid mine water discharged into the environment.Pollution prevention and treatment options were identified and discussed in this study which consists of wet treatment of dust, planning, collection and treatment of mine water, planting of trees for dust and noise reduction as well as minimization of erosion. Some recommendations are made for pollution abatement from coal production and improvement of anthracite production in the region.     

Policing and polluting: The role of practices in contemporary urban environmental pollution governance

Over the past 30 years, urban environmental pollution governance has been increasingly influenced by ideas of New Public Management. However, there is increasing evidence that it is failing in its promise to deliver efficient and effective regulation. The critiques are mounting of risk-based approaches, where regulators are increasingly accountable for the costs (and benefits) of their interventions upon firms.There is a particular lack of research on the role of conduct and practices involved on the ‘front line’ of regulation. This constrains our ability to understand how more efficient effective urban environmental pollution control might develop. This paper focuses on the regulator field officers and business duty holders of environmental compliance, who have direct contact in the processes and administration of regulation. Applying theories of social practice to environmental regulation, the paper provides new insights into compliance and enforcement practices, as these workers seek to prevent pollution, remediate sites and manage waste. The analysis reveals disconnects between expectations of enforcing and managing compliance; and between practices of policing and polluting.Using an ethnographic-informed approach to understand the social practices of regulation has not been attempted in this way before. It reveals new insights into limitations of current approaches to regulation, and indicates interventions that could lead to improved compliance outcomes in a post-New Public Management era in urban pollution governance.     

Corporate social responsibility in the mining industry: Exploring trends in social and environmental disclosure

In recent years, concerns about the sustainability and social responsibility (CSR) of businesses have become an increasingly high profile issue in many countries and industries, none more so than the mining industry. For mining, one outcome of the CSR agenda is the increasing need for individual companies to justify their existence and document their performance through the disclosure of social and environmental information. This paper explores recent trends in the reporting of such impacts and issues in the global mining industry. It offers a detailed review of the development of the media of social and environmental disclosure in the mining industry, and of the factors that drive the development of such disclosure. A temporal analysis of the recent trends in disclosure using a case study of the world's 10 largest mining companies is presented. Whilst there is evidence of increasing sophistication in the development of social and environmental disclosure, there is considerable variation in the maturity of reporting content and styles of these companies. The paper offers a simple classification of reporting companies, from ‘leaders’ to ‘laggards’. Stronger leadership and co-operation from the top reporting companies is necessary to support the laggards of the industry.     

An approach and preliminary model of integrating ecological and economic constraints of environmental quality in the Guayas River estuary, Ecuador

We describe conceptual and simulation models of land use within the intertidal zone of the Guayas River estuary to quantify the contribution of mangrove wetlands to maintaining environmental quality of a tropical estuary. The goal of this exercise is to demonstrate the important consideration of ecological constraints in determining economic and management decisions; and how modeling can be used to quantify impacts of land use such as loss of mangrove wetlands on environmental quality. Our conceptual model treats solar energy, river flow, and tides as forcing functions that control the properties of estuarine ecosystems, but also describes market forces and cultural policies as constraints on properties of socioeconomic systems. The controversy of coastal resource management in Ecuador centers around the relative impacts of shrimp pond construction and management as negative feedbacks to the environmental quality of the Guayas River estuary. Unique oceanographic processes and land use changes contribute to complex issues of water and habitat quality in this tropical estuary, the largest estuarine complex on the Pacific coast of South America. A dynamic box model was developed for the estuary and calibrated with data collected from a 14 month survey of water quality parameters throughout the estuary. Scenarios included conversion of mangroves to shrimp ponds in three regions of the estuary, and the construction of a dam by varying three different rates of river discharge at 100, 50 and 10% of 1989 base flow. Good water quality is maintained by the low residence time of water in the estuary (11 d) because of seasonally high river flow and tidal exchange. With a 90% reduction of mangrove forests in the estuary caused by shrimp pond construction, total nitrogen concentrations increased 5 fold. However, as river discharge decreased to 10%, the same construction caused a 60 fold increase in nitrogen concentrations to 250 μM. Increases in nitrogen concentrations were higher in the upper estuary region, with much less change in the lower estuary. Thus the sensitivity of environmental quality to changes in land use in the intertidal and upland zone are linked to the hydrography of the estuary and is site specific. In the future, the combinations of these ecological models together with economic analyses of the goods and services of mangroves may provide better techniques to evaluate the economic impacts of specific coastal zone management decisions.     

Can integrated control strategies for multiple emissions enhance cost-efficiency in environmental policy?: Evidence from Sweden

The aim of this paper is to clarify the magnitude of the sub-optimization cost associated with separate control strategies for compliance with the Swedish environmental quality objectives. The marginal reduction costs are estimated using a separate and an integrated version of a deterministic linear programming model. To investigate whether the accuracy of the data is decisive for the result of this study, an extensive sensitivity analysis that deals with both the disparity in discount rates in data and the different types of measures, is carried out in four steps. It can be concluded that the results are robust for possible and probable faults in data. The main findings are that there are no substantial sub-optimization costs for separate control strategies for CO₂, NO_X and SO₂, but an integrated action strategy could imply enhanced cost-efficiency in reductions of VOC and particles.     

包头市环境污染治理设施第三方运营利弊分析及对策建议

第三方运营管理模式是环境污染治理设施运营管理深入发展的必然趋势。本文就包头市区域性、集约式污染治理设施以及环境污染重点行业企业污染源治理设施实施第三方运营的制约因素和有利因素开展研究,为包头市推行环境污染源治理设施的治理集约化、产权多元化、运营市场化在制度机制建设和政策措施保障等方面提出合理化建议,从而使第三方运营的管理模式更好的为包头市环保工作服务。     

Review on environmental policies in China:Evolvement,features,and evaluation

This article reviews the development of current environmental policies in China and the great progress made during 1979–2006. Applying lessons learned from industrialized countries to its own situation, China’s environmental policies have the following main features: (1) to explore command and control measures to their fullest extent, (2) to strive to raise funding for environmental protection, (3) to identify who should take accountability for environmental protection; (4) to encourage strategies of “combination of prevention and control” and “integrated utilization”, (5) to embrace openness in the field of environmental policy and early international cooperation. During the past 30 years, China’s environmental policies have evolved and deepened: status expanded the national basic policies of environmental protection by adding a sustainable development strategy, focus changed from pollution control to a combination of pollution control and ecological protection, method changed from end control to source control, scope changed form point source control to watershed and territory pollution control, and management style changed from primarily using executive power to using legal and economic measures. This article introduces how they are evaluated by the international community and provides the prospects of the policies.     

瑞典维纳恩湖的沉积物和鱼类种群中的汞:污染后的恢复状况

过去流入维纳恩湖的含汞废水颇多.通过连续测定沉积物和鱼体中的汞来监测其影响和恢复状况.汞的主要源头来自湖北岸的一座氯工厂.尽管60年代从源头流出的废水中汞水平有了根本性的减少,附近湖泊沉积物中汞的水平从70年代中期以来只下降了一半多.狗鱼(Esox lucus)体内汞的水平在同期下降的幅度相似.湖泊受影响最大的部分比受影响最小的部分要高出30%.湖泊中的鲈鱼(Percafhviatilis)和三文鱼鱼体内汞水平不高.尽管维纳恩湖沉积物中汞水平有所增加,比起位于同一地区而没有受当地汞废水污染湖泊内的鱼来说,维纳恩湖鱼体内汞的水平相对来说并不算高.据估算,湖内鱼类总生物量所含的汞不到湖泊底部沉积物上层活性生物层所含汞总量的千分之一.这显示了各种环境因子的潜在影响,并促使我们将来要继续对汞水平进行监测.     

A review of the state of research,policies and strategies in addressing leakage from reducing emissions from deforestation and forest degradation (REDD+)

Leakage from policies to reduce emissions from deforestation and forest degradation (REDD+) must be monitored, measured and mitigated to ensure their effectiveness. This paper reviews research on leakage at the large (international and national) and small (subnational and project) scales to summarize what we already know, and highlight areas where research is urgently needed. Most (11 of 15) studies published until 2005 estimated leakage of fossil-fuel-based emissions from large-scale interventions such as the United Nations Framework Convention on Climate Change Kyoto Protocol. Many studies on leakage from landuse-based emissions more relevant for REDD+ emerged afterwards (11 of 15), mostly focusing on smaller-scale interventions (8 of the 11 studies). There is a deficiency in qualitative studies showing how leakage develops from an intervention, and the factors influencing this process. In–depth empirical research is needed to understand activities and actors causing emissions (Emissions), the way those activities move spatially in response to policies (Displacement), the way policies affect carbon (C) emitting activities (Attribution) and the amount of resulting emissions produced (Quantification). The cart is thence before the horse: the knowledge necessary to form practical and accurate working definitions, typologies and characterizations of leakage is still absent. Despite this, there is a rush to measure, monitor and mitigate leakage. The concept of leakage has not matured enough, leading to vague definitions of leakage, its components, and scale. We suggest ways to improve the concept of leakage and argue for more empirical research and at various scales to add to our collective knowledge of Emissions, Displacement, Attribution and Quantification.