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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Fechamento de mina : análise de casos selecionados sob os focos ambiental, econômico e social

Camelo, Marta Sawaya Miranda January 2006 (has links)
Submitted by Maurílio Figueiredo (maurilioafigueiredo@yahoo.com.br) on 2013-02-22T20:37:44Z No. of bitstreams: 1 DISSERTAÇÃO_FechamentoMinaAnálise.pdf: 10307728 bytes, checksum: 1e0a8b681953d6247fca43770c70a6dc (MD5) / Approved for entry into archive by Neide Nativa (neide@sisbin.ufop.br) on 2013-02-25T14:20:57Z (GMT) No. of bitstreams: 1 DISSERTAÇÃO_FechamentoMinaAnálise.pdf: 10307728 bytes, checksum: 1e0a8b681953d6247fca43770c70a6dc (MD5) / Made available in DSpace on 2013-02-25T14:20:57Z (GMT). No. of bitstreams: 1 DISSERTAÇÃO_FechamentoMinaAnálise.pdf: 10307728 bytes, checksum: 1e0a8b681953d6247fca43770c70a6dc (MD5) Previous issue date: 2006 / ABSTRACT: The concern about the environment come imposing itself for a few decades, becoming today, a world phenomenon and causing a rethink of attitudes in all the activities that intervene direct or indirectly in the environment. In the mining, according to this new conscience, the society also comes demanding a new boarding for the question of mine closure (known internationally for design for mine closure). A joint effort has been materialized, causing adjustments in the mining projects since its implantation, until its deactivation and closing, as well as in the legal systems that intervene in this aspect in Brazil. There is still a lack of studies developed in this area and a lot still has to be done, therefore the choice of the subject for this thesis. It is intended, during this work: to present a description of the evolution of Brazilian legislation; to approach some aspects of the international legislation relating them with the current trends; to propose a discussion about effectiveness of the fulfillment of the legislation and its impediments in the process of mining closure. It is expected to culminate this work discussing concrete cases of mining closure that allow the improvement of future plans of mining closure. / A preocupação com a questão ambiental vem se impondo há algumas décadas, tornando-se, hoje, um fenômeno mundial e provocando um repensar de atitudes em todas as atividades que interferem direta ou indiretamente no meio ambiente. Na mineração, em decorrência dessa nova consciência, a sociedade vem exigindo uma nova abordagem também para a questão do fechamento de mina (conhecido internacionalmente por design for mine closure). Um esforço conjunto vem se materializando, provocando ajustes nos projetos de mineração desde sua implantação até sua desativação e fechamento, bem como nos ordenamentos jurídicos que interferem nesse aspecto no Brasil. Ainda são poucos os estudos desenvolvidos nessa área, e muito ainda precisa ser feito, por isso a escolha do tema para essa dissertação. Pretende-se, no desenrolar deste trabalho: apresentar um histórico da evolução da legislação brasileira vigente; abordar alguns aspectos da legislação internacional relacionando-as com as tendências atuais; propor uma discussão sobre a efetividade do cumprimento da legislação e seus entraves no processo de fechamento de mina. Espera-se culminar esse trabalho discutindo casos concretos de fechamento de mina que permitam o aprimoramento de futuros planos de fechamento de mina. __________________________________________________________________________________________________________________________________________________
2

Tratamento de incertezas no planejamento do fechamento de mina. / Dealing with uncertainty in the mine closing planning.

Neri, Ana Claudia 23 May 2013 (has links)
Incertezas são inerentes ao planejamento de fechamento de mina, atividade que requer o trato de complexas questões técnicas, sociais, econômicas e ambientais em perspectiva de longo prazo e com base em informação e conhecimentos fragmentados e não sistemáticos. Incertezas nas tomadas de decisões podem resultar em ações de fechamento ineficazes e/ou ineficientes, ou seja, que não alcancem os objetivos esperados e/ou demandem vultosos recursos financeiros, humanos e outros. Esta pesquisa procurou compreender a natureza das incertezas presentes no processo de planejamento de fechamento de mina por meio da definição de suas causas, tipos e formas de tratamento e analisar como são abordadas em guias de boas práticas. Incerteza, no contexto do planejamento de fechamento de mina, é entendida como uma situação na qual há conhecimento incompleto, imprevisibilidade ou não há um único entendimento do processo a ser gerenciado. Nesse contexto, as principais causas das incertezas são, respectivamente, insuficiência de conhecimento, variabilidade do comportamento dos componentes do processo, no tempo e no espaço e diferentes enfoques ou recortes da situação analisada. Foram definidos oito tipos de incertezas pertinentes ao planejamento de fechamento de mina, agrupadas em três componentes (i) naturais (incertezas ambientais, geológicas, geotécnicas), (ii) técnicos (incertezas operacionais, tecnológicos), (iii) socioeconômicos (incertezas sociais, regulatórias, gerenciais, econômicas). Associações de empresas e órgãos públicos têm publicado guias e documentos de diretrizes para orientar as empresas a planejar o fechamento de mina. No entanto, esses guias não parecem ser explícitos quanto ao reconhecimento e tratamento de incertezas no planejamento de fechamento. Assim, por meio da técnica de análise de conteúdo, quatro guias de boas práticas foram examinados para verificar, se e como, abordam ou recomendam diretrizes para lidar com incertezas no planejamento de fechamento. Os resultados mostraram que certos tipos de incerteza são reconhecidos pelos guias, que recomendam algumas diretrizes para lidar, em especial, com incertezas ambientais, sociais, regulatórias e econômicas. Porém, (i) os guias não demonstram uma clara concepção ou entendimento das incertezas inerentes ao planejamento de fechamento de mina, embora em algumas situações reconheçam sua existência e influência; (ii) a maior ênfase dos guias em relação aos aspectos ambientais pode induzir as empresas a alocarem responsabilidades para tratar questões relativas ao fechamento ao departamento de meio ambiente ou de relações comunitárias e não induzirem que sejam tratadas a nível estratégico pela alta direção da empresa e (iii) a maioria dos guias, não fornece diretrizes para melhorar e avaliar a qualidade das informações/conhecimento nas tomadas de decisões. É proposto um esquema analítico para lidar com as incertezas no planejamento de fechamento, composto por três etapas: (i) identificação dos tipos de incertezas; (ii) definição das causas das incertezas e (iii) definição de ações e estratégias para lidar com as incertezas. Espera-se que a proposta possa contribuir para que as empresas de mineração considerem, de maneira estruturada, as incertezas em suas decisões relativas ao fechamento, e que órgãos públicos possam utilizá-la para avaliar as informações apresentadas em planos de fechamento e demais estudos técnicos relativos à autorização e licenciamento de projetos. / Uncertainties are intrinsic to the mine closure planning, activity which involves complex long-term technical, social, economic and environmental questions, based on fragmented and non-systematic information and knowledge. Uncertainties in decision-making may lead to inefficacious closing actions, which do not achieve the expected goals and/or demand a lot of financial, human and other types of resources. This research aimed at understanding the nature of the uncertainties involved in the mine closure planning process by defining their causes, types and ways to deal with them and analyzing how they are treated in best-practice guidelines. Uncertainty in the context of mine closure planning is understood as a situation in which there is incomplete knowledge, unpredictability or no single way to understand the process to be managed. In this context, the main causes of uncertainties are respectively: lack of knowledge, time and space variability of the behavior of the components in the process and different approaches or understanding about the analyzed situation. Eight types of uncertainties regarding the mine closure planning have been defined and grouped in three components: (i) natural (environmental, geological and geotechnical uncertatinty), technical (operational and technological uncertatinty), (iii) social- economical (social, regulatory, management and economic uncertainties). Enterprises associations and public agencies have been publishing guidelines to provide the companies with advice on how to plan the mine closure. However, these guidelines do not seem to be explicit in recognizing and dealing with uncertainty in the closure planning. Thus, using the content analysis technique, four best practice guidelines have been examined in order to determine whether and how they approach or produce advice to deal with uncertainty in the closure planning. The results have shown that certain types of uncertainty are addressed by the guidelines, which provide some advices to deal particularly with environmental, social, regulatory and economic uncertainties. Nevertheless, the guidelines: (i) do not present a clear concept or understanding about the uncertainty which are intrinsic to the mine closure planning, although in some situations the recognize their existence and influence; (ii) the higher emphasis on the environmental aspects used by the guidelines may induce the companies to allocate reponsibilities to deal with x questions related with the closure, the environmental department or the relations with the community and cause them not be treated in strategic level by the company and (iii) most guidelines do not provide advices on how to improve and evaluate the quality of the information/knowledge of the decision-making. An analytical scheme composed by three steps is proposed to deal with the uncertainties in the closure planning: (i) identification of the uncertainty type; (ii) definition of uncertainty causes and (iii) definitions of actions and strategies to deal with uncertainties. This proposal may contribute for the mining companies to consider in a structured way the uncertainties in their closure-related decisions and for the public agencies to evaluate the information present in closure plans and other technical studies related to licensing projects.
3

Sistematização de procedimentos para o fechamento temporário de minas de agregados

Centeno, Camila Lamonato January 2017 (has links)
O presente trabalho descreve uma metodologia utilizada para a construção de um procedimento padronizado a ser utilizado por técnicos do Departamento Nacional de Produção Mineral (DNPM) para avaliação de solicitação de suspensão temporária do empreendimento por um período determinado. O método está implementado através de um formulário construído para ser aplicado na fiscalização de campo prevista na legislação mineral em caso de solicitação de suspensão das atividades de mineração, inicialmente com proposta de aplicação em minas a céu aberto de agregados. A proposta desenvolvida parte do princípio que a justificativa apresentada pela empresa é satisfatória e que ela entregou todos os documentos previstos na legislação, também de maneira satisfatória e sistematiza itens de caráter atual do empreendimento para classificar de forma padronizada e objetiva o estado atual da unidade solicitante. A metodologia possui a intenção de complementar a análise, torná-la menos subjetiva e confirmar as informações contidas nos documentos entregues. O procedimento também visa que os impactos sejam mitigados e que a área permaneça sob cuidados permanentes do empreendedor, sem agravamento dos passivos, assim como, possibilite a retomada das operações de forma segura. / This work describes a methodology used to construct a standard procedure to be used by technicians of the National Department of Mineral Production (DNPM) to evaluate the request for mining temporary suspension for a certain period. The method is implemented through a form, built to be applied in the field inspection provided for the mineral legislation in case of request for suspension of the mining activities, initially with proposal of application in open cast mines of aggregates. The idea developed assumes that the justification presented by the company is satisfactory and that it showed all documents provided for the legislation, also in a satisfactory manner. It systematizes items of current character to classify in a standardized and objective way the mine that is requesting suspension. The methodology intents to complement the analysis, make it less subjective and confirm the information contained in the submitted documents. The procedure also aims at mitigating the impacts and that the area remains under permanent care and maintenance, without aggravating the liabilities, as well as, enable to return the operations in a safe way.
4

Impacts of mining and mine closure on water quality and the nature of the shallow aquifier, Yandi Iron Ore Mine

Gardiner, Sean Jonathan January 2003 (has links)
The Hamersley Yandi Iron Ore Mine of Hamersley Iron Pty. Ltd. is located in the Pilbara region, Western Australia, approximately 90km north west of the town of Newman. The iron ore has accumulated in a palaeochannel as an enriched Channel Iron Deposit (CID). Mining in other parts of this palaeochannel has been practised since 1991. Named deposits in the province are, from west to east, Munjina, Pool, Meander, Western, Central, Eastern, Junction and the Billiard deposits.Presently the CID acts as an aquifer and transmits water through its fracture system. It is the main conduit for the regional groundwater. The Water and Rivers Commission of Western Australia considers the groundwater in the alluvial beds of the Weeli Wolli Creek overlying the CID to be a useful resource. The groundwater is currently used for stock watering so the quality should be preserved.Part of the four possible closure plans of the Yandi Mine is to backfill the excavated channel with waste rock from the mining operation. The waste material will consist of the uneconomic grade lateritic pisolite iron ore, together with colluvium and alluvium overburden. The closure plans will also leave behind two pit lakes.The impact of these closure plans vary but each plan will leave pit lakes containing water with high salinity and this may adversely affect the quality of the groundwater downstream of the lakes.The hydraulic conductivity of the shallow aquifer may be impaired by swelling clays found in parts of the waste material. This impact would be reduced if the chosen closure plan was one with hydrogeological flow management.The water quality downstream of the pit lakes will change and the environmental impact on the groundwater will depend on which closure plan is chosen. This thesis suggests a number of options for consideration.
5

Mount Morgan: images and realitiesdynamics and decline of a mining town

Cosgrove, Betty Alveen, b.cosgrove@cqu.edu.au January 2001 (has links)
Most histories and reports of Mount Morgan concentrate on the mining experience and financial achievements of the first Company rather than the mining town. This dissertation presents a social history of Mount Morgan that addresses the establishment, rise and fall of the town during the period of the first syndicate and succeeding company, 1883-1927. The thesis contends that the transformation of the landscape was to industrial, urban space where the working-class attitudes of miners and others defined a town character, despite the aspiration of many to social status through private enterprise and public influence. Further, the scope of research encompassed local involvement in colonial and state politics, and the presence of local government authority, law courts and press that placed an urban stamp on the town. Issues discussed also relate to geographic, climatic and single company influences that caused the difference between Mount Morgan and other mining towns that did not survive. The traditional perception of mining town impermanence was contradicted at Mount Morgan, where town and suburban communities were witness to a range of collective support in religious adherence, benefit associations, fraternalism and ritual, leisure, sport, education, and social cohesion in times of mining disaster. Moreover, despite increasing familial connections, antagonistic attitudes prevailed between the defensively parochial town of Mount Morgan and the nearby regional centre of Rockhampton. The rise of unionism at Mount Morgan challenged an apathetic working-class population to workplace solidarity in reaction to the Company's long established, almost feudal control of the town as well as the mine. It is argued that, despite a decade of failing ore markets and soaring production costs at the mine, the attitudes and actions of a union dominated workforce were paramount in decline of the town and ultimate closure of the mine. Mount Morgan survived the exodus of thousands of residents. A defiant place, the town exhibited a pride bolstered by the perpetuation of myths that presented a public image shielded from the life-long realities of economic and social adversity.
6

Sistematização de procedimentos para o fechamento temporário de minas de agregados

Centeno, Camila Lamonato January 2017 (has links)
O presente trabalho descreve uma metodologia utilizada para a construção de um procedimento padronizado a ser utilizado por técnicos do Departamento Nacional de Produção Mineral (DNPM) para avaliação de solicitação de suspensão temporária do empreendimento por um período determinado. O método está implementado através de um formulário construído para ser aplicado na fiscalização de campo prevista na legislação mineral em caso de solicitação de suspensão das atividades de mineração, inicialmente com proposta de aplicação em minas a céu aberto de agregados. A proposta desenvolvida parte do princípio que a justificativa apresentada pela empresa é satisfatória e que ela entregou todos os documentos previstos na legislação, também de maneira satisfatória e sistematiza itens de caráter atual do empreendimento para classificar de forma padronizada e objetiva o estado atual da unidade solicitante. A metodologia possui a intenção de complementar a análise, torná-la menos subjetiva e confirmar as informações contidas nos documentos entregues. O procedimento também visa que os impactos sejam mitigados e que a área permaneça sob cuidados permanentes do empreendedor, sem agravamento dos passivos, assim como, possibilite a retomada das operações de forma segura. / This work describes a methodology used to construct a standard procedure to be used by technicians of the National Department of Mineral Production (DNPM) to evaluate the request for mining temporary suspension for a certain period. The method is implemented through a form, built to be applied in the field inspection provided for the mineral legislation in case of request for suspension of the mining activities, initially with proposal of application in open cast mines of aggregates. The idea developed assumes that the justification presented by the company is satisfactory and that it showed all documents provided for the legislation, also in a satisfactory manner. It systematizes items of current character to classify in a standardized and objective way the mine that is requesting suspension. The methodology intents to complement the analysis, make it less subjective and confirm the information contained in the submitted documents. The procedure also aims at mitigating the impacts and that the area remains under permanent care and maintenance, without aggravating the liabilities, as well as, enable to return the operations in a safe way.
7

Sistematização de procedimentos para o fechamento temporário de minas de agregados

Centeno, Camila Lamonato January 2017 (has links)
O presente trabalho descreve uma metodologia utilizada para a construção de um procedimento padronizado a ser utilizado por técnicos do Departamento Nacional de Produção Mineral (DNPM) para avaliação de solicitação de suspensão temporária do empreendimento por um período determinado. O método está implementado através de um formulário construído para ser aplicado na fiscalização de campo prevista na legislação mineral em caso de solicitação de suspensão das atividades de mineração, inicialmente com proposta de aplicação em minas a céu aberto de agregados. A proposta desenvolvida parte do princípio que a justificativa apresentada pela empresa é satisfatória e que ela entregou todos os documentos previstos na legislação, também de maneira satisfatória e sistematiza itens de caráter atual do empreendimento para classificar de forma padronizada e objetiva o estado atual da unidade solicitante. A metodologia possui a intenção de complementar a análise, torná-la menos subjetiva e confirmar as informações contidas nos documentos entregues. O procedimento também visa que os impactos sejam mitigados e que a área permaneça sob cuidados permanentes do empreendedor, sem agravamento dos passivos, assim como, possibilite a retomada das operações de forma segura. / This work describes a methodology used to construct a standard procedure to be used by technicians of the National Department of Mineral Production (DNPM) to evaluate the request for mining temporary suspension for a certain period. The method is implemented through a form, built to be applied in the field inspection provided for the mineral legislation in case of request for suspension of the mining activities, initially with proposal of application in open cast mines of aggregates. The idea developed assumes that the justification presented by the company is satisfactory and that it showed all documents provided for the legislation, also in a satisfactory manner. It systematizes items of current character to classify in a standardized and objective way the mine that is requesting suspension. The methodology intents to complement the analysis, make it less subjective and confirm the information contained in the submitted documents. The procedure also aims at mitigating the impacts and that the area remains under permanent care and maintenance, without aggravating the liabilities, as well as, enable to return the operations in a safe way.
8

Tratamento de incertezas no planejamento do fechamento de mina. / Dealing with uncertainty in the mine closing planning.

Ana Claudia Neri 23 May 2013 (has links)
Incertezas são inerentes ao planejamento de fechamento de mina, atividade que requer o trato de complexas questões técnicas, sociais, econômicas e ambientais em perspectiva de longo prazo e com base em informação e conhecimentos fragmentados e não sistemáticos. Incertezas nas tomadas de decisões podem resultar em ações de fechamento ineficazes e/ou ineficientes, ou seja, que não alcancem os objetivos esperados e/ou demandem vultosos recursos financeiros, humanos e outros. Esta pesquisa procurou compreender a natureza das incertezas presentes no processo de planejamento de fechamento de mina por meio da definição de suas causas, tipos e formas de tratamento e analisar como são abordadas em guias de boas práticas. Incerteza, no contexto do planejamento de fechamento de mina, é entendida como uma situação na qual há conhecimento incompleto, imprevisibilidade ou não há um único entendimento do processo a ser gerenciado. Nesse contexto, as principais causas das incertezas são, respectivamente, insuficiência de conhecimento, variabilidade do comportamento dos componentes do processo, no tempo e no espaço e diferentes enfoques ou recortes da situação analisada. Foram definidos oito tipos de incertezas pertinentes ao planejamento de fechamento de mina, agrupadas em três componentes (i) naturais (incertezas ambientais, geológicas, geotécnicas), (ii) técnicos (incertezas operacionais, tecnológicos), (iii) socioeconômicos (incertezas sociais, regulatórias, gerenciais, econômicas). Associações de empresas e órgãos públicos têm publicado guias e documentos de diretrizes para orientar as empresas a planejar o fechamento de mina. No entanto, esses guias não parecem ser explícitos quanto ao reconhecimento e tratamento de incertezas no planejamento de fechamento. Assim, por meio da técnica de análise de conteúdo, quatro guias de boas práticas foram examinados para verificar, se e como, abordam ou recomendam diretrizes para lidar com incertezas no planejamento de fechamento. Os resultados mostraram que certos tipos de incerteza são reconhecidos pelos guias, que recomendam algumas diretrizes para lidar, em especial, com incertezas ambientais, sociais, regulatórias e econômicas. Porém, (i) os guias não demonstram uma clara concepção ou entendimento das incertezas inerentes ao planejamento de fechamento de mina, embora em algumas situações reconheçam sua existência e influência; (ii) a maior ênfase dos guias em relação aos aspectos ambientais pode induzir as empresas a alocarem responsabilidades para tratar questões relativas ao fechamento ao departamento de meio ambiente ou de relações comunitárias e não induzirem que sejam tratadas a nível estratégico pela alta direção da empresa e (iii) a maioria dos guias, não fornece diretrizes para melhorar e avaliar a qualidade das informações/conhecimento nas tomadas de decisões. É proposto um esquema analítico para lidar com as incertezas no planejamento de fechamento, composto por três etapas: (i) identificação dos tipos de incertezas; (ii) definição das causas das incertezas e (iii) definição de ações e estratégias para lidar com as incertezas. Espera-se que a proposta possa contribuir para que as empresas de mineração considerem, de maneira estruturada, as incertezas em suas decisões relativas ao fechamento, e que órgãos públicos possam utilizá-la para avaliar as informações apresentadas em planos de fechamento e demais estudos técnicos relativos à autorização e licenciamento de projetos. / Uncertainties are intrinsic to the mine closure planning, activity which involves complex long-term technical, social, economic and environmental questions, based on fragmented and non-systematic information and knowledge. Uncertainties in decision-making may lead to inefficacious closing actions, which do not achieve the expected goals and/or demand a lot of financial, human and other types of resources. This research aimed at understanding the nature of the uncertainties involved in the mine closure planning process by defining their causes, types and ways to deal with them and analyzing how they are treated in best-practice guidelines. Uncertainty in the context of mine closure planning is understood as a situation in which there is incomplete knowledge, unpredictability or no single way to understand the process to be managed. In this context, the main causes of uncertainties are respectively: lack of knowledge, time and space variability of the behavior of the components in the process and different approaches or understanding about the analyzed situation. Eight types of uncertainties regarding the mine closure planning have been defined and grouped in three components: (i) natural (environmental, geological and geotechnical uncertatinty), technical (operational and technological uncertatinty), (iii) social- economical (social, regulatory, management and economic uncertainties). Enterprises associations and public agencies have been publishing guidelines to provide the companies with advice on how to plan the mine closure. However, these guidelines do not seem to be explicit in recognizing and dealing with uncertainty in the closure planning. Thus, using the content analysis technique, four best practice guidelines have been examined in order to determine whether and how they approach or produce advice to deal with uncertainty in the closure planning. The results have shown that certain types of uncertainty are addressed by the guidelines, which provide some advices to deal particularly with environmental, social, regulatory and economic uncertainties. Nevertheless, the guidelines: (i) do not present a clear concept or understanding about the uncertainty which are intrinsic to the mine closure planning, although in some situations the recognize their existence and influence; (ii) the higher emphasis on the environmental aspects used by the guidelines may induce the companies to allocate reponsibilities to deal with x questions related with the closure, the environmental department or the relations with the community and cause them not be treated in strategic level by the company and (iii) most guidelines do not provide advices on how to improve and evaluate the quality of the information/knowledge of the decision-making. An analytical scheme composed by three steps is proposed to deal with the uncertainties in the closure planning: (i) identification of the uncertainty type; (ii) definition of uncertainty causes and (iii) definitions of actions and strategies to deal with uncertainties. This proposal may contribute for the mining companies to consider in a structured way the uncertainties in their closure-related decisions and for the public agencies to evaluate the information present in closure plans and other technical studies related to licensing projects.
9

Sinkhole formation due to subsurface erosion above undermined ground

Breyl, Jacobus January 2019 (has links)
In November 2016, 38 sinkholes formed due to subsurface erosion above undermined ground on Donkerhoek farm near Sasolburg. The fact that the sinkholes formed more than 24 years after mining in the area ceased, emphasised the need for a method to predict the likelihood of sinkhole formation due to subsurface erosion. This is especially relevant for mining houses required to quantify their mine closure risks. The purpose of this study was to investigate the mechanisms and soil properties involved in the formation of the 38 sinkholes on Donkerhoek farm through a fieldwork and laboratory testing programme and develop a method to predict the likelihood of sinkhole formation. Three areas were selected for test pit excavation: an area with large sinkholes, one with small sinkholes and a third with no sinkholes but with a history of subsidence crack formation. The same mechanism of sinkhole formation was observed in both the large and small sinkhole areas: at the soil-rock interface, soil was being eroded into a subsidence crack in the rock, resulting in an upwards migrating cavity and the eventual formation of a sinkhole on surface when the cover over the cavity collapsed. This was the first time that this mechanism was observed in the Sasolburg area, having previously only been identified in the Secunda area. The laboratory tests, carried out on samples obtained during the fieldwork, included foundation indicator, dispersivity, XRF and XRD, soil water retention curves, consolidated undrained triaxial and permeability tests. By comparison of the results from the different study areas, it was concluded that the larger sinkholes form in areas with highly dispersive soils, higher clay content, higher swell potential and a higher capacity to retain suctions when wetted. The following soil properties and factors were identified as the main contributors to sinkhole formation: • The strength of the lid, which is highly influenced by the unsaturated behaviour of the lid material. The lid strength determines the sinkhole diameter; • The erodibility of the material which is influenced by dispersivity and the material obtaining a crumb structure due to desiccation; • The activity of the soil, which influences the volume changes during drying and thereby the width and depth of desiccation cracks; and • The thickness of the soil layer overlying the rockhead. With the critical factors identified, the Van der Merwe method to predict sinkhole size was used as basis to develop an index method to predict the likelihood of sinkhole formation due to subsurface erosion above undermined ground. The method considers combinations of the following factor groups to express a high or low likelihood of the formation of large or small sinkholes in a particular area: • The strength of the lid material, mainly influenced by the unsaturated behaviour of the soil; • The capacity for cavity formation (CCF), which combines the dispersivity, erodibility and activity of the soil; and • The influence of the thickness of the soil layer overlying the rock, evaluated by calculating the ratio between crack width in the rock and the soil layer thickness. / Dissertation (MEng)--University of Pretoria, 2019. / Civil Engineering / MEng (Geotechnical Engineering) / Unrestricted
10

Filling Method Implementing Hydraulic Lime for Reusing Mine Tailings and Improve Sustainability in Conventional Peruvian Underground Mines

Altamirano-Soto, Pablo, Supa-Urrutia, Jorge, Pehovaz-Alvarez, Humbero, Raymundo, Carlos, Mamani-Macedo, Nestor, Dominguez, Francisco 01 January 2020 (has links)
El texto completo de este trabajo no está disponible en el Repositorio Académico UPC por restricciones de la casa editorial donde ha sido publicado. / Mining in Peru has existed for several decades, and for several years, there has been no proper environmental management of the impact of this activity on the environment and society in general, whether it be gas emissions, the presence of acidic water, or the generation of mining tailings. One of the most prominent examples involve mine tailings; these are by-products of mining processing plants and are stored in a dam known as a tailings dam. Like any extraction activity, mining generates large amounts of waste material that could become potential risks to the environment and society. Using hydraulic fills, the mine tailings contained in tailings dams could be reused. These fills seek to decrease the volume of stored tailings to prevent any future dam collapses, as observed in Brazil with the Vale mining company, where its tailings dam collapsed and caused more than 200 deaths.

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