Marcello Veiga


Relevant Degree Programs


Graduate Student Supervision

Doctoral Student Supervision (Jan 2008 - May 2019)
Learning from artisanal miners : a model for designing training programs with and for the artisanal mining sectoa (2018)

Worldwide, approximately 30 million people depend directly on artisanal mining of many different minerals to provide for themselves and their families. There has yet to be a successful and concerted effort to tackle the barriers which keep artisanal miners trapped in a cycle of poverty and poor environmental and health practices. The purpose of this thesis is to define how a successful training program for artisanal miners should be designed and how the program can be measured and evaluated. This research posits that for a training program to be successful, it should be designed based on a deep appreciation for the unique context in which the training takes place. Monitoring and evaluation of the program must be conducted thoroughly and consistently. Qualitative research methods were used to analyze a suite of training programs for artisanal miners to inform the design of a suite of Training Needs Assessment research tools, which were field-tested in Indonesia. This study found that training programs on mitigating environmental impacts of artisanal mining, formalizing artisanal miners, mercury eradication and occupational health and safety have not taken into account the context of the artisanal mining sector. The needs and motivations of the miners are often ignored and therefore, training programs have seen little sustained success. The amount of time and patience it requires for there to be uptake is often overlooked. A six-step framework for training artisanal miners was developed as an output of this thesis and can be used by practitioners so that the design, launch and evaluation of training programs for artisanal miners can be done more thoroughly and consistently.

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Indigenous communities sustainable development framework for LNG developments in Northwest B.C. (2017)

The extractives sector has the obligation to contribute to sustainable development in areas where resource exploitation occurs. Fulfilling this expectation is challenging in resource-dependent towns, that are periodically exposed to boom-bust dynamics. In northwest British Columbia, several large Liquefied Natural Gas (LNG) terminal projects have been proposed, involving high capital costs and several thousand workers for the construction phase. Indigenous Peoples are often negatively affected by such large developments, as their culture and sustenance is tied to the land and water. Many of these peoples are also unable to benefit from such developments, due to a lack of support mechanisms and the necessary training or education required for good paying jobs. This study investigates how large resource developments can contribute to sustainability in B.C. First Nations communities by finding ways to enhance benefits and minimize impacts from boom-bust dynamics. Two socio-economic surveys were conducted with the Kitsumkalum First Nation, which is one of the Tsimshian Tribes potentially affected by LNG developments. Additionally, 31 interviews were conducted with LNG, mining, government, economic development and First Nations representatives, from which common themes were identified and ranked. Results showed that although high school graduation rates (16% to 34%), university education rates (4.5% to 7.3%), and unemployment rates, (29.2% to 17.2%) have improved for on-reserve Kitsumkalum members between 2006 and 2016, many continue to struggle economically. Education, training and employment (ETE) was collectively ranked by all interviewed sectors as the most important for First Nations to move towards a sustainable future, while all sectors individually ranked ETE as No. 1, except for First Nations, who ranked the removal of social barriers as No. 1 and ETE as No. 2. The need for good governance to roadmap effective changes was ranked No. 2, while the need to remove social barriers was ranked No. 3 by all sectors. In light of these results, a new framework was proposed, which incorporates the need for community characterization, a strategic sustainable development plan, good governance, and improved shared decision making and partnerships, in order to better facilitate sustainable development of Indigenous communities within the context of large-scale resource developments.

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Socio-Economic Mine Closure (SEMC) framework : a comprehensive approach for addressing the socio-economic challenges of mine closure (2014)

This thesis seeks to investigate the initiatives that address the socio-economic implications of mine closure that have been implemented by three mining companies which are located in Mongolia, Argentina and Canada. It further addresses the perceptions of stakeholders, specifically community members, local government representatives and mining company employees regarding the initiatives that have been implemented by three mining companies. Additionally, the research examines six mining industry-related frameworks/guidelines, and explores the ways in which these documents interpret the socio-economics of mine closure. Finally, this thesis introduces and evaluates the Socio-Economic Mine Closure (SEMC) Framework, which was originally developed as part of this PhD investigation. There are 10 elements in the Framework: Policy, Presence, Participation, Planning, Performance, Promotion, Perseverance, Patience, Passion, and Personality.The SEMC Framework is assessed in multiple ways: a) against the current literature on mine closure; b) through an online survey in which 151 experts were invited to provide feedback on the elements and sub-element constituents of the Framework and c) by its utility in constructing the fieldwork survey and the feedback of survey participants indicating the appropriateness of the framework.The study indicates that it would be relevant, timely and appropriate for the mining industry to introduce, discuss and adopt the proposed SEMC Framework.The case study analyses, all of which employed interviews, group sessions, and distribution of survey material as part of their methodological approaches, reveal that each case has unique characteristics and that all are context-based. The case studies also indicate that all three situations reveal the presence of some common issues. For instance, the results of the study suggest that, in all three cases, communication levels need to be improved and augmented.An important finding of the overall study concerns the element Personality within the SEMC Framework. Although in both the online survey and in the survey distributed to study participants, this element was ranked as one of low importance, through the interviews, group sessions and researcher observations it became clear that the Personality of the company community liaison does play a significant role in maintaining and fostering relationships between mining companies and local stakeholders.

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Urban atmospheric mercury contamination from artisanal mining : mapping, modeling, and mitigation (2014)

Artisanal miners in more than 70 countries extract gold using mercury, which isoften evaporated in densely populated urban areas. This work explores the behaviour ofthese emissions, and the potential implications for human health. Maps of urban mercuryconcentrations are used to evaluate the impact of mercury reduction interventions andestimate the distribution of health hazard. Atmospheric dispersion modeling is also usedto corroborate inferences about the behaviour of urban mercury vapour that are derivedfrom observations, and to simulate hazard distributions.Miners decompose the amalgams (with 50 to 60% mercury) and melt the rawgold in shops located near the centre of each town without sufficient condensers orfilters. The average concentrations measured by mobile mercury vapour analyzertransects taken repeatedly over several weeks were 1.25 μgm -³ in 2010 in Segovia and0.331 μgm -³ in Andacollo (2009). Mobile mercury measurements and atmosphericdispersion modeling both indicate that mercury emissions from gold shops, though high,dissipate rapidly in space and time.Mobile mercury mapping along streets can detect most frequent emitters withonly a few weeks of mobile sampling. Observations of concentrations greater than1 μgm -³ indicate that within the past 5 minutes amalgam was being burned within a 200metre radius. Measurements from towers show the temporal variability of mercuryconcentrations, and show that large quantities of mercury are available for long-rangeatmospheric transport.By World Health Organization (WHO) standards, these towns are exposed to asignificant health hazard, and globally, the millions of miners as well as non-miners wholive in similar towns are at serious risk of neurological and renal disease. Various directand indirect indicators of gold production and mercury reduction also show thatmitigation efforts by the United Nations Industrial Organization (UNIDO) in Colombiahave reduced urban airborne mercury concentrations by approximately 50% in Segovia,Antioquia, despite a 30% increase in gold production during that three year period. Thisis attributable to the adoption of retorts by miners and regulations banning newprocessing centres to the rural periphery.

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Quantifying, reducing and improving mine water use (2013)

Water is vital to the mining industry; mines can require substantial amounts of water and are often located in some of the driest places on earth. Reducing water withdrawals and improving mine water use are key strategic requirements for moving toward a more sustainable mining industry. Mine water requirements often have significant technical, economic, environmental and political implications. This thesis quantifies global mine water withdrawals and discusses methods of improving mine water use by reducing water withdrawals and water-related energy consumption.The thesis is composed of four main sections. First, two methods are proposed to calculate global mining water withdrawals by commodity. One method is based on the amount of water required to process a tonne of ore and the other is based on the amount of water required to produce a tonne of concentrate. A large database was created, compiling data regarding ore production, commodity production, commodity prices, and mine water withdrawals between 2006 and 2009. The study estimates that global water withdrawals range from 6 to 8 billion m3 per annum. Second, the thesis presents a case study on the challenges faced and lessons learned during the design, start-up and modification of the water systems of a large copper mine site. Third, the thesis identifies multiple mine water reduction, reuse and recycle strategies that have been implemented around the world. A model is developed and used to show the potential impact of these strategies. The results of the modelling show how a hypothetical mine could reduce water withdrawals from 0.76 m³/t to 0.20 m³/t of ore processed or lower. In particular, the combination of ore pre-concentration and filtered tailings disposal reduced water consumption by over 74% of the base case. Finally, this thesis describes and demonstrates a method of determining the lowest energy option for a mine water network. The method uses a linear programming algorithm to compare options for matching water sources with consumers at mine sites. An example illustrates the method and shows how mine water system energy requirements can be reduced by over 50%.

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Gender differentiated impacts and benefits of artisanal mining : engendering pathways out of poverty. A case study of Katwe-Kabatooro Town Council, Uganda (2011)

Artisanal and small scale mining (ASM) is a crucial livelihood for over 20 million miners in developing countries throughout the world (Veiga and Baker, 2004). Despite misperceptions of “mining as men’s work”, ~40-50% of Africa’s artisanal miners are women who occupy critical roles in commercial, domestic and social spheres (Lahiri Dutt, 2003; Hinton et al, 2003a). The widespread poverty, environmental degradation and poor social conditions which characterize the ASM poverty cycle are largely attributed to its informal nature and use of crude technologies while its capacity to reduce poverty through increased incomes is also well recognized. Numerous policy reforms and interventions have been implemented accordingly with variable success.This research posits that ASM policy and action must further be informed by understanding of factors that determine livelihood outcomes through a gender lens. Both quantitative and qualitative methods were used to investigate the gender-differentiated constraints facing women and men miners compared to those in fishing, trading and other activities as well as the main assets or poverty reducing measures to which they have access.Based on a case study in the salt mining community of Katwe-Kabatooro Town Council in Western Uganda, it was found that women are clearly disadvantaged in most assets that comprise the foundation for sustainable livelihoods. Nevertheless, many women miners’ vulnerability has prompted them to “trade up” their assets of labour, cash and growing social capital through livelihood diversification, leading to improved socio-economic and health outcomes. While this suggests a clear pathway out of poverty, the majority of women miners often cope by using strategies that compromise their wellbeing, with far reaching implications for themselves and the community. Although a number of women have been able to overcome major constraints, gender inequalities were shown to play a prominent role in exacerbating the ASM poverty cycle. Findings point to women’s lack of autonomy and decision-making power as a root cause of negative outcomes for health and wellbeing of both women and men. If ASM policy and technical intervention increase emphasis on building human and social capital, more success can be achieved in realizing the poverty reduction potential of ASM.

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The demographic, economic and health fabric of mining communities in British Columbia, Canada (2011)

A significant number of communities in British Columbia (BC) are founded on mineral development and are subject to variable economic boom-and-bust cycles with implications for sustainability and community health. There were three main objectives of this multi-method PhD dissertation. The first was to quantitatively examine community level indicators describing economic, sustainability, and demographic characteristics (gained from Canadian Census data) of 31 BC rural resource based communities (with a focus on mining communities) during a period of time (1991 to 2001) when BC resource sectors experienced an economic downturn. The second was to assess the relationship between exposure to declining economic conditions and acute cardiovascular disease, chronic cardiovascular disease, and mental health outcomes in 29 BC rural resource-based using Statistics Canada Labour Force Survey data and Ministry of Health data over the same time period, again with a focus on mining. The third objective was to qualitatively investigate the experiences of health and social service providers using interviews, with respect to community health issues and the boom-bust mining cycle in a Northern remote coal mining community in British Columbia. During the decade under study, demographic and economic indicators indicated that mining communities were dependent on, and vulnerable to, economic activities and identified the need to strategize the sustainability of mining communities in British Columbia. Health data indicated that declining and bust economic conditions had a significant negative impact on the prevalence of acute cardiovascular disease and mental disorders in mining communities. Qualitative data revealed that the mining boom-bust cycle had negative effects on community health issues, and community health service provision. This dissertation concludes by proposing strategic opportunities aimed at the enhancement of mining community health and sustainability for policy-makers, communities, the mining industry and researchers to consider.

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Mercury in artisanal and small scale gold mining : identifying strategies to reduce environmental contamination in Southern Ecuador (2010)

This investigation builds on research about mercury use in custom processing centers in Portovelo-Zaruma Southern Ecuador, where around 3000 people are directly involved to produce around 9 tonnes/annum of gold. The lack of understanding about mercury dynamics during gold processing reduces the development of appropriate solutions to mitigate the environmental contamination. The analysis of the amalgamation systems in 8 centers indicated that 12 to 40% of the total mercury used in the process has been evaporated when amalgams are burned, 40 to 60% of mercury has been recovered and 1 to 35% of mercury has been lost with the tailings. The amalgamation of the whole ore in barrels (“Chanchas”) contributes to the highest concentrations of mercury in tailings (350 ppm Hg). Around 1.5 tonnes/annum of mercury has been likely released to the environment in Portovelo from which 71% goes to the air and the remaining mercury enters the cyanidation process. As amalgamation does not extract all the gold present in the ore, the mercury rich-tailings are processed with cyanide preferentially through Merrill-Crowe or Carbon in Pulp (CIP) system. The analysis of 7 cyanidation processing plants revealed that 51% and 14% of mercury is released as dissolved mercury from CIP and the Merrill-Crowe process respectively. Approximately 27% of mercury is released to the atmosphere with the Merrill-Crowe when zinc shavings are burned. The CIP process releases 3.72% of mercury during carbon elution. A laboratory cyanidation test confirmed that mercury dissolution from tailings is much slower than gold dissolution. The established division of labor in place among miners and owners of processing centers forces the use of mercury in amalgamation combined with cyanide leaching. As miners do not understand the actual process, they accept low levels of gold recovery by amalgamation, leaving the rich tailings to the owners of processing centers. This generates dependency on mercury and reduces the opportunity to improve the system. One lesson gleaned from this study is that a participatory integrated assessment approach may contribute to learning, increasing awareness, and it can help identify practical and effective options for reducing mercury contamination in artisanal gold mining operations.

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Planning and implementing solutions for artisanal gold mining sites, preventing environmental impacts and rehabilitating degraded areas : a Brazilian case study (2010)

Artisanal small scale gold mining (ASGM) is a large source of environmental, health and safety problems in more than 70 developing countries, employing more than 15 million people, motivated by the current high price of gold and lack of better economic opportunities. Around 200,000 miners are located in Brazil with 40,000 concentrated in the Tapajos River Basin, in the Amazon. In this region, they extract gold by using rudimentary processes, causing mercury contamination, river siltation and deforestation. This thesis conducted research in the Tapajós region highlighting the strengths of some initiatives introduced by the GEF/UNDP/UNIDO Global Mercury Project from 2002 to 2008. Its training program was delivered to 4,200 artisanal miners in 141 mining sites, and it focused on disseminating 20 good mining practices. Performance indicators have shown that the conformance to standards before and after the program improved from 22 to 51%, with highest success on reduction of mercury (43%) and river siltation (37%), and improvement of sanitation (40%) in the participating sites. This study suggests the use of a heuristic approach to environmental impact assessment and ways to address those variables in intervention programs through training and education. The study also presents a successful rehabilitation initiative using simple local materials. In the participating sites 128 pits were backfilled after training and some of them revegetated. In another case study, a pilot plant to pre-concentrate gold with centrifuge followed by intensive cyanidation of the concentrate in a ball mill has demonstrated to be a fast and advantageous alternative to replace the current 20-day vat leaching or even amalgamation. This pilot study reduced cyanide consumption more than 20 times and may represent an economy of US$150,000/a in NaCN. Finally, this study analyzes 20 Brazilian regulations that affect ASGM, shows that many of them have not been effective, and suggests recommendations that would help to organize the miners and give them proper access to training, technical assistance and technology.

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Realities and perceptions of human rights and the mining industry : a case study (2009)

Dealing with realities and perceptions of human rights in the mining industry context is important. Significant socio-economic risks to existing and potential mining operations arise when mining companies are believed responsible for or complicit in human rights abuses. Mining engineers responsible for projects need adequate awareness and sufficient capacity to manage these risks effectively. This research proceeded in two ways after reviewing the history of the evolution of human rights: It studied important examples of alleged human rights violations associated with mining companies, large and small. Historical data and the evolution of attitudes and perceptions within and about the Rio Tinto mining company’s operations worldwide were also examined. Qualitative research based on interviews with former and current executives and staff in Rio Tinto, other companies, government and civil society provided original data and captured perceptions, awareness, attitudes and practices. A categorized database developed with 178 cases of allegations of human rights abuses shows the breadth of the human rights challenges. Principal reasons why the question of human rights and the mining industry is important, including identified points of conflict between mining and society, were explored. Case studies were organized by point of conflict (use of security forces, indigenous peoples, labour rights, “pariah” or failing states, and national and regional jurisdiction conflict). Existing industry safeguard policies, practices, monitoring, verification and reporting were examined. The research determined, from recent evidence and allegations of complicity in human rights abuses, that voluntary initiatives alone are inadequate. Failures of host governments and companies to protect human rights necessitate effective mechanisms to investigate, and hold accountable, companies complicit in human rights abuses.A method was recommended for the industry to engage positively with all stakeholders in the mineral development cycle. Policies, codes, principles, checklists, voluntary initiatives, best practices, monitoring, verification and compliance reporting are recommended to exploration and mining companies serious about making commitments to respect human rights.

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Mineworkers' quality of life in remote communities : a multiple case study in the Brazilian Amazon (2008)

The mining industry has long played a significant role in regional development in remote regions throughout the world. For the last two decades, the industry has faced high expectations regarding sustainable development and corporate social responsibility, particularly in remote and environmentally sensitive areas. Mining community models and mineworkers’ accommodation strategies in remote locations have varied greatly, yet there has been little documented reflection on the various models’ performance or on their implications for the quality of life (QOL) of mineworkers and their families and for the pre-existing local communities. This multidisciplinary case study research used a subjective quality of life approach to investigate the levels of satisfaction with QOL and specific aspects of QOL domains in three communities: the company town, the gate development community and the integrated community. The triangulation of data from qualitative and quantitative methods was used to examine the major QOL factors that should be taken into account by mining companies, local governments and policy makers when planning for mine development in remote areas. Findings suggest that differences exist between the mineworkers’ levels of satisfaction with specific QOL aspects and how QOL predictors are defined in distinct mining community models. Even though the case studies represent clearly different models of mining communities, in general, mineworkers in the three communities seem to be only moderately satisfied with their quality of life. It is also suggested that employees living in two almost opposite models—the company town and the gate development community—seem to have similar levels of satisfaction with overall quality of life, suggesting that the investment in infrastructure and services limited to the boundaries of the company town is not reflected in a generally improved perception of overall quality of life in this community. Findings also support the argument for an environmental and social impact assessment process for new mines in remote areas. This process should include a full and integrated consideration of the economic, environmental and social impacts of the workforce migration to remote areas and the consequent intensification of the already rapid urbanization of environmentally sensitive areas such as the Brazilian Amazon.

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System Analysis Perspective: Lead-Acid Battery Recycling in British Columbia, Canada (2008)

No abstract available.

Master's Student Supervision (2010 - 2018)
A diagnostic assessment of operational, environmental and safety procedures in the onshore cassiterite artisanal mining sector in Indonesia (2018)

Cassiterite (SnO₂) is the main ore-mineral of tin, with tin constituting 78.8% and oxygen 21.2%. It is mostly mined in secondary deposits. Tin is one of the components in electronics like computers and smart phones, solder to produce welding wire and is also part of steel plates, which is commonly used in cars and of cans. Considering the world annual production of approximately 280,000 tonnes of tin, resources should sustain production for another 30 years. Approximately 97% of the world’s metallic tin comes from emerging and developing countries and around 25% of cassiterite around the globe is mined by artisanal miners, who use rudimentary techniques, resulting in frequent accidents and occupational hazards that generate health problems for operators and neighbors. The second largest producer of cassiterite in the world, the production of Indonesian artisanal miners constitutes about 40% of the global tin market. Indonesia’s export of tin in 2016 totaled almost 64,000 tonnes. Approximately 60% of cassiterite concentrate production in Indonesia, in 2017, came from artisanal miners in two islands, Bangka and Belitung, in 10,000 mining sites in total (Bangka 8,000 and Belitung 2,000), with more than 50,000 artisanal cassiterite miners (Bangka 40,000 and Belitung 10,000 miners), plus dependents. An individual artisanal miner making approximately US $176 per month. In comparison, the minimum wage in Indonesia is US$ 198/month. Tin recovery was estimated in 12% (metallurgical recovery), whereas the concentrate mass yield was calculated in 0.004% (mass recovery). Cassiterite is mined and processed by artisanal miners in Indonesia using simple techniques consisting of hoses, pumps and poorly constructed sluices boxes. Sixty miners died in Indonesia artisanal cassiterite mining per year, mostly buried in tin alluvial mines or trapped underwater during dredging offshore mining activities. The most common occupational risks are the risk of block sliding, falling and wall collapse. In order to improve organization, formalization, capacity building and, the passing of laws and standards to regulate the sector, important steps should be pursued. Moreover, a stronger and more effective government interference in inspection and training, and willingness of the stakeholders for implementing improvements are imperative.

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Business solutions to the formalization of artisanal gold mining (2016)

Artisanal and Small-scale Mining (ASM) exists in virtually every developing country with accessible mineral deposits. Typically ASM is an informal or in some cases illegal activity with numerous problems associated with it including mercury pollution, non-existent health and safety standards and abusive child labour practices. Furthermore ASM is often regulated to a “subsistence” activity that, along with poor financial management among the miners, keeps participants trapped in a cycle of poverty. Nonetheless, ASM is remarkably productive and has the potential to be extremely profitable as well as environmentally and socially responsible given guidance and formalization. Efforts to formalize ASM activity thus far have been government-led, top-down, heavy-handed attempts to police an activity that employs an estimated 20-30 million people world-wide, often in remote places and often in situations where they believe they have no economic alternative for survival. Not surprisingly, these efforts have met with limited success. The productive and potentially very profitable nature of this activity, where there is no shortage of demand for their extremely fungible product, lends itself readily to a business approach. Franchise businesses are effective in markets where consistency in operations and production are required, especially where such operations are attractive to capable local operators. The franchise model offers access to finance, improved technical capacity for increased recovery, business management expertise, access to banking and personal financial guidance, and a mechanism to reduce environmental and social risk. Furthermore, investors are increasingly wary of investing in junior mining companies as country-risk, resource nationalism, and social license to operate act as impediments to a project’s timely entry to production. ASM offers high social license with local operators and well-diversified country risk. Thus, a small-scale gold mining franchise offers an appealing opportunity to manage, as well as diversify against, such risk factors, while remaining in an extremely profitable and hitherto unexplored market. The reality in many places in Latin America is that partnerships with community locals have a much higher success rate than businesses without. Even nationals from other localities experience difficulties such as additional or longer permitting and harassment. This dynamic provides additional advantages to franchise structures.

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Geochemical assessment of the bioavailability of platinum group metals for phytomining (2016)

Phytomining is suggested as a novel technology to obtain platinum group metals (PGMs) nanoparticles from plants grown on the mineralized soil, rock, or on mine wastes. The primary determinant of metal uptake by a plant is the bioavailability of the metal in the soil-plant system. In this thesis project, the bioavailability of PGMs of several PGM-rich materials is assessed with respect to phytomining. Notably, feed, concentrate and tailings from North American Palladium (NAP) in Canada, and two gossan samples from Broken Hill (BH) mineral complex in Australia are assessed in the context of phytomining. Geochemical techniques are used to obtain the mineralogy, the total concentration of PGMs, and concentrations of PGMs extracted by chemicals. These methods assess the bioavailability of PGMs in the samples and enable the estimation regarding the available concentrations of Pd, Pt, Au and Cu to plants. Soil-associated factors such as pH, salinity (EC), and cation exchange capacity (CEC) have been shown to influence indirectly the bioavailability of PGMs. Thus, soil-associated factors were analyzed. Additionally, a selection model for the substrate of phytomining is proposed. The criteria for choosing substrate for the phytomining of Pd include available Pd concentration, pH, EC, CEC and available Cu concentration. This thesis concludes that the PGM species that can be extracted by ammonium acetate are the best indicators of their natural availability to plants. Those PGMs that can be extracted by fulvic acid and citrate-dithionite are good indicators as they can be soluble in soils. According to the selection model, the available Pd concentration of BH gossan 1 is higher than 2 mg/kg. Its low EC, high CEC, and proper pH make it a suitable substrate for plant growth. It is the best “one” of the five samples for phytomining of Pd. One thing to note is that high Cu-tolerant plant species should be chosen to grow on BH gossan 1 due to its high Cu concentration available to plants.

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Process analysis and energy efficiency improvement on Portland limestone cement grinding circuit (2015)

Worldwide cement production is a high energy consuming industry; 90% is thermal and 10% is electrical energy. This is the third most anthropogenic related carbon dioxide emitting industry in the world. With a rising price of energy and a growing emphasis on environmental issues the cement industry is facing significant challenges to both remain a competitive and sustainable. Composite cement manufacturing is one alternative that is used reduce energy use and greenhouse gas emissions. The dry grinding process used for finished product represents 40-50% of electrical energy consumption. It is a very inefficient process generally ranging around 1% efficient. This research evaluated the process of a typical Portland cement grinding circuit in order to identify inefficiencies in the process and how the operating parameters may be changed in order to improve the system’s performance. Tests were conducted using samples from a B.C. cement producer and results analyzed in order to characterize and build a high accuracy model that can be used as a bench marking tool. Representative sampling and mass balance were performed on the circuit using real steady state operative conditions data provided by process plant managers. Major research findings are:• Air separator efficiency is rated 46.06% efficiency at fractions below 35 microns.• High dust load feed and agglomeration are the main reasons for this low separator efficiency.• Agglomeration effect is related to overgrinding, high energy impacts and the use of limestone.• Whiten model is an adequate tool to fit and correct experimental data on cement air separators and to provide quantification of operating factors to evaluate the separation process.• Low grinding kinetics at ball mill compartment 01, suggests improper size grinding media selection and high wear rate for the case studied (for media and liners).

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Myths and realities in artisanal gold mining mercury contamination (2013)

The world faces a major gold rush currently. Worldwide 15 million people work directly in artisanal gold mining in more than 55 countries. The usual method of extraction is amalgamation and cyanidation, or very commonly a combination of both. Significant amounts of contaminants are released to rivers and soil, generating environmental and health concerns. The majority of artisanal miners are involved in micro-mining, but it is believed that the majority of contamination comes from small to large artisanal operations. Larger operations involve less people, but process much more material, re-leasing much more contaminants as well. The present work explains how contamination is generated, through a com-prehensive analysis of the labor division in small-scale mining sites around the world, and also analyses aspects of different intervention approaches.Different approaches are taken by different groups working on the problem around the world. This work evaluates the most common kinds of interven-tion, with special attention to technical and legal aspects in trying to eliminate mercury use in gold extraction. The study is conducted by comparing differ-ent interventions strategies to evaluate the myths and realities from an engineering perspective. Special attention is paid to the evaluation of alterna-tives to amalgamation process for gold such as intensive cyanidation, borax direct smelting and chlorination. Accordingly to the location in which the technology is introduced, different methods can be applied, but only cyanide remains a proven method to deal with complex ores.Important aspects such as education, training, financial aid and understand-ing of a community before intervention are also shown to be essential for success.The association of Small-scale Gold Mining and potential gold concentrate consumers is pointed to as a possible solution, applicable where concentrates can be shipped to a smelter. Association with large companies is cited as an alternative means to reduce contaminants generated by gold extraction as well.

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