This thesis is motivated by problems studied as part of the Diavik Waste Rock Pile Project. Located at the Diavik Diamond Mine in the Northwest Territories, with academic support from the University of Waterloo, the University of Alberta, and the University of British Columbia, this project focuses on constructing mine waste rock piles and studying their physical and chemical properties and the transport processes within them. One of the main reasons for this investigation is to determine the effect of environmental factors on acid mine drainage (AMD) due to sulfide oxidation and the potential environmental impact of AMD. This research is concerned with modeling pressure driven flow through waste rock piles. Unfortunately, because of the irregular shape of the piles, very little data for fluid flow about such an obstacle exists, and the numerical techniques available to work with this domain are limited. Since this restricts the study of the mathematics behind the flow, this thesis focuses on a cylindrical domain, since flow past a solid cylinder has been subjected to many years of study. The cylindrical domain also facilitates the implementation of a pseudo-spectral method. This thesis examines a pressure driven flow through a cylinder of variable permeability subject to turbulent forcing. An equation for the steady flow of an incompressible fluid through a variable permeability porous medium is derived based on Darcy's law, and a pseudo-spectral model is designed to solve the problem. An unsteady time-dependent model for a slightly compressible fluid is then presented, and the unsteady flow through a constant permeability cylinder is examined. The steady results are compared with a finite element model on a trapezoidal domain, which provides a better depiction of a waste rock pile cross section.

Acid Mine Drainage (AMD) is an environmental problem that eventually occurs in sulfide rich mine sites. In Turkey most of the metal mines are associated with sulphide minerals and are potential AMD generators. The purpose of this PhD thesis is to practice universally accepted tools for the prediction of AMD potential for a new metallic mine development. This study involves evaluation of geological data, geochemistry, mineralogy, and acid-base accounting (static tests) data, obtained from the Erzincan-ili&ccedil / &Ccedil / &ouml / pler Gold Prospect case. The mineralization in &Ccedil / &ouml / pler is in sulfide and oxide types. The oxide is a supergene alteration and porphyry-copper type gold mineralization is classified as an intermediate sulfidation. The major lithologies observed in the study area are the regionally un-correlated meta-sedimentary lithologies, Munzur Limestone, and the &Ccedil / &ouml / pler Granitoid.Thirty-eight representative samples were tested for AMD prediction purposes. Sixteen more were included to the sampling scheme for site characterization. Both acid producing and neutralizing lithologies are present in the mine site. Similarly it was revealed that the sulphate sulfur content of the samples were insignificant that any determined total sulfur amount can be directly considered as the factor for AMD production. Geochemical data revealed arsenic enrichments up to 10000 ppm in the study area. Therefore, during the operational stage, in addition to the planning to avoid or minimize AMD, it is necessary to take precautions against arsenic mobilization during the design of the AMD neutralization scheme. Both Kinetic studies and the heavy metal mobilization related to AMD are kept out of the scope of this investigation. Similarly, management and abatement stages of AMD are excluded.

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains viii, 92 p. : ill., maps (some col.). Includes abstract. Includes bibliographical references (p. 56-62).

The processes that control the reductive dissolution of Mn0₂ by Fe(II) under conditions simulating the effects of acid mine drainage on subsurface environments and the subsequent precipitation of Fe(III) has been investigated. Results from real-time, in situ X-ray absorption spectroscopy (XAS) flow-through reaction cell studies indicate that a mixed Fe/Mn solid phase with the local structure of the spinel mineral jacobsite (MnFe₂O₄) is formed after the Mn0₂ surfaces are coated with ferric precipitates. In the absence of previously precipitated Fe(III), no reduced manganese solid is formed. The ferric precipitates do not incorporate significant quantities of Mn(II) down gradient from the reactive Fe(II) front. The maximum amount of the original Mn0₂ incorporated into this jacobsite-like solid is 5%. Results from batch experiments showed similar results compared to the flow-through experiments, with an initially fast rate of Mn(II) release, followed by a much slower release after 5-10 min had elapsed. The reaction products, Fe(III)(aq) and Fe(III)(s) were found to decrease the initial reaction rate. A simple model was developed to describe the temporal concentrations of Mn(II)(aq), Fe(II)(aq), and Fe(III)(aq) that include a Langmurian blocking function to describe the effects of the ferric reaction products on the reaction rate. The model also allowed for a second order process to occur at long time that was dependent solely on the aqueous concentrations of Fe(II) and Mn02. The formation of the ferric reaction products were found to transform from aqueous sulfate complexes to (presumable) ternary surface complexes with sulfate. Within 10 h, these precipitates may have formed chains of edge-sharing octahedra on the order of 60 Å. The precipitates have large amount of sulfate associated with them, which may preclude the formation of ferrihydrite, and may indicate the formation of schwertmannite. The average Fe:SO₄ ratio was 4.4 ± 1.0, a value similar to that reported for schwertmannite. The presence of goethite was identified by X-ray diffraction as early as 50 d, indicating that sulfate is being excluded from the precipitates. The release of Mn(II), FeT, and sulfate was controlled by diffusion, which may also be the process that controls the rate of transformation.

No description available.

Laboratory and field studies were completed to characterize the geochemistry and microbiology of drainage emanating from low-S content waste-rock test piles at the Diavik Diamond Mine (Diavik) from 2007 through 2010. The potential use of small-scale laboratory humidity-cell experiments to predict the water quality from larger-scale field-based experiments also was examined. Waste rock at Diavik is segregated into three categories according to sulfide content: Type I (target concentration: < 0.04 wt. % S), Type II (target concentration: 0.04 to 0.08 wt. % S) and Type III (target concentration: > 0.08 wt. % S). Four high-density polyethylene tanks, 2 m in diameter by 2 m in height, were filled with and surrounded by waste rock (active zone lysimeters; AZLs) at the Diavik site to study the upper 2 m of the active zone within a waste-rock pile and to evaluate the quality of effluent released from waste rock with differing S contents (Type I AZLs: 0.014 wt. % S and Type III AZLs: 0.035 wt. % S). In addition, three waste-rock test piles also were constructed at Diavik, two uncovered test piles (Type I test pile: 0.035 wt. % S and Type III test pile: 0.053 wt. % S) and a third pile was constructed based on the mine-closure plan which consists of waste rock (Type III: 0.082 wt. % S) capped with a 1.5 m layer of till and a 3 m layer of Type I material (Covered test pile). Each test pile is underlain by a high-density polyethylene geomembrane that captures and directs water to outflow drains. Results show that the release and transport of blasting residuals could be used as a resident tracer, indicating the first flush of water through the AZLs and the test piles. Variations in concentrations of blasting residuals and the gradual rate of dissipation provide an indication of the heterogeneity of the distribution of blasting residuals and the relative contributions of water and solutes from different flow paths. As temperatures within the test piles increase in response to ambient air temperature increases, larger proportions of the test pile contributed to the outflow, and increased concentrations of blasting residuals were observed in waste-rock test pile effluent. Effluent from the Type I AZLs and test pile maintained near-neutral pH (ranged from 5.8 to 8) with concentrations of SO₄²⁻ < 500 mg L⁻¹. These results suggest that the near-neutral pH values were associated with the presence of carbonates in the waste rock and the lack of intense acid generation. As ambient air temperatures increased in spring and summer of each year, the measured pH in the Type III test-pile drainage decreased from near-neutral in May (pH 7.5) to acidic conditions by October (ranged from 5 to 4.5). As the pH in the Type III test pile decreased, concentrations of SO₄²⁻ and dissolved metals increased (e.g. SO₄²⁻ > 1500 mg L⁻¹) suggesting sulfide oxidation was occurring. Maximum concentrations of SO₄²⁻, Al, Zn, Ni, Co, and Cu were observed in 2009 during the first flush of water through the Type III test pile. A sequence of acid-neutralization reactions was inferred based on the water chemistry of the effluent derived from the Type III AZLs and waste-rock test pile. This acid-neutralization sequence is similar to those observed at other AMD impacted sites. A series of mineral dissolution-precipitation reactions controlled pH and metal mobility; carbonate-mineral dissolution consumed H⁺ generated from sulfide-mineral oxidation at near neutral pH and the dissolution of Al and Fe (oxy)hydroxides consumed H⁺ at pH < 5.0. The cover system on the Covered test pile dampened the effects of ambient air temperature on the internal temperatures within the core of the Covered test pile. As a result, the Covered test pile had a relatively steady change in flow rate, with decreased flow from June to August, which led to a slow but prolonged release of sulfide-mineral oxidation products, such as SO₄²⁻ and dissolved metals, including Ni, Co, Zn, Cd, and Cu, compared to the uncovered Type III test pile. The pH decreased in 2008 and remained low for the duration of the study, whereas the pH in the uncovered test pile was near-neutral at the beginning of each field season in May and decreased to < 4.2 by the end of the field season in November. The microbiological-community profiles observed in the AZLs and waste-rock test piles suggest typical AMD-related species were present in acidic effluent with elevated concentrations of metals, whereas typical soil microbes were present in effluent with a near-neutral pH and lower concentrations of SO₄²⁻ and dissolved metals. The Type III AZLs, Type III test pile, and Covered test pile maintained populations of acidophilic Fe-oxidizers, whereas, the Type I AZLs and Type I test pile maintained populations of neutrophilic S-oxidizers. Laboratory humidity-cell (1 kg) results were scaled up to estimate the water quality from the Type III AZLs (6 t) using measured physical and chemical parameters. The results suggested over-prediction of SO₄²⁻ and metal concentrations when low mean annual precipitation occurred, limiting flushing of predicted oxidation products. In subsequent years with higher mean annual precipitation oxidation products from previous years were liberated and resulted in the under prediction of SO₄²⁻ and metal concentrations. Additionally, Fe and Al were over-predicted because Fe and Al concentrations in the AZL effluent may be controlled by the solubility and formation of secondary minerals, such as Fe oxyhydroxides, jarosite, and goethite, which were not included in the scaling procedure.

Laboratory and field studies were completed to characterize the geochemistry and microbiology of drainage emanating from low-S content waste-rock test piles at the Diavik Diamond Mine (Diavik) from 2007 through 2010. The potential use of small-scale laboratory humidity-cell experiments to predict the water quality from larger-scale field-based experiments also was examined. Waste rock at Diavik is segregated into three categories according to sulfide content: Type I (target concentration: < 0.04 wt. % S), Type II (target concentration: 0.04 to 0.08 wt. % S) and Type III (target concentration: > 0.08 wt. % S). Four high-density polyethylene tanks, 2 m in diameter by 2 m in height, were filled with and surrounded by waste rock (active zone lysimeters; AZLs) at the Diavik site to study the upper 2 m of the active zone within a waste-rock pile and to evaluate the quality of effluent released from waste rock with differing S contents (Type I AZLs: 0.014 wt. % S and Type III AZLs: 0.035 wt. % S). In addition, three waste-rock test piles also were constructed at Diavik, two uncovered test piles (Type I test pile: 0.035 wt. % S and Type III test pile: 0.053 wt. % S) and a third pile was constructed based on the mine-closure plan which consists of waste rock (Type III: 0.082 wt. % S) capped with a 1.5 m layer of till and a 3 m layer of Type I material (Covered test pile). Each test pile is underlain by a high-density polyethylene geomembrane that captures and directs water to outflow drains. Results show that the release and transport of blasting residuals could be used as a resident tracer, indicating the first flush of water through the AZLs and the test piles. Variations in concentrations of blasting residuals and the gradual rate of dissipation provide an indication of the heterogeneity of the distribution of blasting residuals and the relative contributions of water and solutes from different flow paths. As temperatures within the test piles increase in response to ambient air temperature increases, larger proportions of the test pile contributed to the outflow, and increased concentrations of blasting residuals were observed in waste-rock test pile effluent. Effluent from the Type I AZLs and test pile maintained near-neutral pH (ranged from 5.8 to 8) with concentrations of SO₄²⁻ < 500 mg L⁻¹. These results suggest that the near-neutral pH values were associated with the presence of carbonates in the waste rock and the lack of intense acid generation. As ambient air temperatures increased in spring and summer of each year, the measured pH in the Type III test-pile drainage decreased from near-neutral in May (pH 7.5) to acidic conditions by October (ranged from 5 to 4.5). As the pH in the Type III test pile decreased, concentrations of SO₄²⁻ and dissolved metals increased (e.g. SO₄²⁻ > 1500 mg L⁻¹) suggesting sulfide oxidation was occurring. Maximum concentrations of SO₄²⁻, Al, Zn, Ni, Co, and Cu were observed in 2009 during the first flush of water through the Type III test pile. A sequence of acid-neutralization reactions was inferred based on the water chemistry of the effluent derived from the Type III AZLs and waste-rock test pile. This acid-neutralization sequence is similar to those observed at other AMD impacted sites. A series of mineral dissolution-precipitation reactions controlled pH and metal mobility; carbonate-mineral dissolution consumed H⁺ generated from sulfide-mineral oxidation at near neutral pH and the dissolution of Al and Fe (oxy)hydroxides consumed H⁺ at pH < 5.0. The cover system on the Covered test pile dampened the effects of ambient air temperature on the internal temperatures within the core of the Covered test pile. As a result, the Covered test pile had a relatively steady change in flow rate, with decreased flow from June to August, which led to a slow but prolonged release of sulfide-mineral oxidation products, such as SO₄²⁻ and dissolved metals, including Ni, Co, Zn, Cd, and Cu, compared to the uncovered Type III test pile. The pH decreased in 2008 and remained low for the duration of the study, whereas the pH in the uncovered test pile was near-neutral at the beginning of each field season in May and decreased to < 4.2 by the end of the field season in November. The microbiological-community profiles observed in the AZLs and waste-rock test piles suggest typical AMD-related species were present in acidic effluent with elevated concentrations of metals, whereas typical soil microbes were present in effluent with a near-neutral pH and lower concentrations of SO₄²⁻ and dissolved metals. The Type III AZLs, Type III test pile, and Covered test pile maintained populations of acidophilic Fe-oxidizers, whereas, the Type I AZLs and Type I test pile maintained populations of neutrophilic S-oxidizers. Laboratory humidity-cell (1 kg) results were scaled up to estimate the water quality from the Type III AZLs (6 t) using measured physical and chemical parameters. The results suggested over-prediction of SO₄²⁻ and metal concentrations when low mean annual precipitation occurred, limiting flushing of predicted oxidation products. In subsequent years with higher mean annual precipitation oxidation products from previous years were liberated and resulted in the under prediction of SO₄²⁻ and metal concentrations. Additionally, Fe and Al were over-predicted because Fe and Al concentrations in the AZL effluent may be controlled by the solubility and formation of secondary minerals, such as Fe oxyhydroxides, jarosite, and goethite, which were not included in the scaling procedure.

This thesis is motivated by problems studied as part of the Diavik Waste Rock Pile Project. Located at the Diavik Diamond Mine in the Northwest Territories, with academic support from the University of Waterloo, the University of Alberta, and the University of British Columbia, this project focuses on constructing mine waste rock piles and studying their physical and chemical properties and the transport processes within them. One of the main reasons for this investigation is to determine the effect of environmental factors on acid mine drainage (AMD) due to sulfide oxidation and the potential environmental impact of AMD. This research is concerned with modeling pressure driven flow through waste rock piles. Unfortunately, because of the irregular shape of the piles, very little data for fluid flow about such an obstacle exists, and the numerical techniques available to work with this domain are limited. Since this restricts the study of the mathematics behind the flow, this thesis focuses on a cylindrical domain, since flow past a solid cylinder has been subjected to many years of study. The cylindrical domain also facilitates the implementation of a pseudo-spectral method. This thesis examines a pressure driven flow through a cylinder of variable permeability subject to turbulent forcing. An equation for the steady flow of an incompressible fluid through a variable permeability porous medium is derived based on Darcy's law, and a pseudo-spectral model is designed to solve the problem. An unsteady time-dependent model for a slightly compressible fluid is then presented, and the unsteady flow through a constant permeability cylinder is examined. The steady results are compared with a finite element model on a trapezoidal domain, which provides a better depiction of a waste rock pile cross section.

Os impactos ambientais provocados por determinadas atividades econômicas podem causar prejuízos em terceiros já que a ação deletéria sobre o meio prejudica e, em alguns casos, inviabiliza a existência de outras atividades. Nesse contexto, enquadra-se a mineração de carvão. Em tal atividade, o contato da água – superficial, subterrânea ou pluvial – com elementos específicos resultantes das escavações, na presença de oxigênio e de microorganismos, forma a chamada drenagem ácida de mina que, em grande parte dos casos, é despejada em cursos d’água adjacentes prejudicando outros usos da água. Assim, o presente trabalho tem por objetivo elaborar uma metodologia de planejamento da explotação do carvão mineral em bacias hidrográficas que busque a produção ótima do minério com a internalização dos custos de tratamento do efluente gerado a fim de que os parâmetros de qualidade da água, estabelecidos pela Resolução 357 do CONAMA, sejam respeitados e, desse modo, diminua a incidência de prejuízos em terceiros. Tal metodologia é pautada pela elaboração de um modelo capaz de simular, ao longo do tempo de explotação das minas, a carga de poluentes lançada nos cursos d'água de uma bacia hidrográfica. Após a coleta de dados, a implantação da metodologia se dá por diversos cenários. O primeiro deles é a análise da situação em que não há internalização dos custos ambientais. Constatou-se que os limites estabelecidos pelo CONAMA são ultrapassados. O segundo cenário caracteriza-se pela tentativa de enquadramento dos cursos d’água na classe 1, com a internalização dos custos ambientais. Dadas as condições de tratamento de efluentes, tal enquadramento não foi possível. O terceiro cenário diz respeito à tentativa de enquadramento na classe 3 dadas as mesmas condições do segundo cenário. Os resultados mostram ser possível tal enquadramento. A elevação dos custos ambientais para enquadramento na classe 1 determina o quarto cenário. Ainda como forma de enquadrar os cursos d’água da bacia na classe 1, é estabelecida uma divisão na operação das minas. Assim, no quinto cenário são consideradas apenas três minas e no sexto cenário são consideradas as demais. Além das concentrações de determinados parâmetros ao longo do tempo, também são mostrados os gráficos de produção das minas em cada cenário. Por fim, são comparados os ganhos obtidos em cada cenário e os fluxos de caixa dos cenários 1, 2 e 3 para que sirvam de subsídio para a classificação das águas da bacia segundo a Resolução 357. / The environmental impacts provoked by determined economic activities can cause financial damages to third parts since the deleterious action harms and, in some cases, makes impracticable the existence of other activities. In this context, the coal mining is situated. In such activity, the contact of superficial water, groundwater or rainwater with specific elements resultant from the drillings, in presence of oxygen and microorganisms, forms the acid mine drainage, that, to a large number of the cases, is poured into adjacent rivers harming other uses of the water. Thus, the present work aims to elaborate a methodology of the mineral coal exploitation planning in river basins that achieves the excellent production of the ore with the costs of effluent treatment internalization so that water quality parameters, established by CONAMA’s Resolution 357, are respected and there is no incidence of damages to third parts. Such methodology is based on the elaboration of a model that is capable of simulating, during the mines exploitation time, the load of pollutants launched in river basins water. After the data collection, the methodology is implemented in diverse scenarios. The first one of them is the analysis of the situation where there is no environmental costs internalization. It is evidenced that the limits established are exceeded. The next scenario is characterized by the attempt of framing water courses in class 1, with environmental costs internalization. Given the conditions of treatment of effluent, such framing was not possible. The third scenario considers the attempt of framing in class 3 given the same conditions of scene 2. The results show that the framing is possible. The rise of environmental costs to frame in class 1 determines the fourth scenario. Still as a form to fit water courses in class 1, a division in mine’s operation is established. Thus, in the fifth scenario only three mines are considered and in the sixth scenario the others are considered. In addition to the concentrations of certain parameters during the exploitation period, the graphs of mine production in each scene are also shown. Finally, the profits obtained in each scenario and the cash flows of scenes 1, 2 and 3 are compared in order to serve as subsidy to classify the river basin waters according to CONAMA’s Resolution 357.

A drenagem ácida de mina (DAM) gerada no processo de mineração de carvão, na presença de minerais sulfetados, tem provocado danos ambientais significativos no ecossistema de sua abrangência. Tecnologia de tratamento ativo baseada em processos de Neutralização, Precipitação e Sedimentação tem sido empregada para atenuar a carga de poluentes no efluente, antes do seu descarte em corpos receptores. A mesma, apesar da sua eficiência vem se mostrando bastante onerosa quando aplicada durante um longo período, devido aos custos com insumos, manutenção, potencial humano e energia. Nos últimos anos, vem sendo desenvolvidos sistemas que socorrem-se da ocorrência natural de processos químicos, biológicos e físicos para purificar água de mina contaminada. Estes são designados sistemas passivos, cuja implantação e funcionamento tem se mostrado menos onerosa em relação ao sistema ativo. Capão da Roça, situado no município de Charqueadas é uma das regiões do Brasil onde ocorre contaminação de solos e rios pela DAM gerada a partir de um depósito de rejeitos. Aplicando o fluxograma recomendado por diversos autores para a seleção do sistema passivo, tomando em conta as características do efluente achou-se viável instalar um canal aberto de calcário para o tratamento da DAM do Capão da Roça em virtude de a mesma apresentar acidez maior que a alcalinidade, oxigênio dissolvido maior que 5mg/l, Fe+3 maior que 25% em relação ao Fe2+. A quantidade de efluente e a declividade do terreno da área estudada permite que se opere com vazão maior que 12m3/h no sistema passivo. De acordo com a acidez do efluente foi determinado o tempo de detenção de 1hora para o tratamento da DAM no sistema. A partir de estudos similares sobre o uso de calcário em sistemas passivos, encontrou-se a massa de 338,6 toneladas para o empreendimento funcionar em 10 anos, considerando uma dissolução de calcário de 100%, num canal com 10% de declividade, 1m de profundidade e 2, 5 metros de largura para tamponar uma solução de DAM com vazão de 1000 L.min-1 num canal de 47metros de cumprimento. De acordo com cálculos baseados num modelo empírico, ficou demonstrado que o diâmetro e área de superfície do calcário poderão diminuir ao longo do tempo, considerado a sua dissolução. / Acid mine drainage (AMD) generated in the coal mining process in the presence of sulfide minerals, have been causing significant environmental damages to the ecosystem of its coverage. Active treatment technology based on neutralization, precipitation and sedimentation processes, has been used to alleviate the load of pollutants in the effluent prior to discharges into receiving bodies. Despite their efficiency has proved quite costly when applied over a long period due to input costs, maintenance, manpower and energy. In recent years project defined 'passive treatment' has been developed as the improvement of water quality using only naturally occurring chemical, biological and physical processes, hence, the deployment and operation have been less costly compared to the active systems. Capão da Roça, located in the municipality of Charqueadas is one of the regions of Brazil where occurs contamination of soils and rivers by AMD generated from a waste dump. Using the flowchart recommended by several authors for selecting the passive system, taking into account the wastewater characteristics, was found to be feasible to install an open limestone channel for the treatment of AMD because it has higher acidity than alkalinity, dissolved oxygen greater than 5mg / l, Fe3+ greater than 25 % in relation to Fe2+. The amount of effluent and the slope of the study area terrain allows to operate with a flow rate greater than 12m3/ h in the passive system. According to the acidity of the effluent was determined retention time of 1 hour for the treatment of the AMD system. From similar studies on the use of limestone in passive systems, was found the mass of 338.6 tons for the enterprise operating over 10 years, assuming a 100% limestone dissolution channel with a 10% slope, 1 meter deep and 2,5 meters wide to buffer an AMD solution with a flow rate of 1000 L.min-1 in channel with 47 meters of length. According to the calculations based on empirical model, it was shown that the diameter and the surface area of limestone may decline over time, considering its dissolution.