<p>A lot of mine waste rock and tailings arise from all mining processes and have to be stored in an appropriate way. Tailings are deposited in impoundments retained by tailings dams. The objective of tailings dams is to retain the slurry from the mining process and in that way prevent spill into the surroundings that might be harmful for the environment. Tailings dams are often constructed as staged embankments so that construction costs and demand of materials are spread more evenly over the period of deposition.</p><p>The objective of this thesis has been to compile information about and evaluate events at Swedish tailings dams and also to develop a collective database for all Swedish mining companies for all tailings dams and all events that occur at tailings dams.</p><p>Information about 60 events at Swedish tailings dams has been gathered and evaluated. The evaluation has been performed by comparison between and analysis of individual parameters and also by use of a multivariate statistical method called PLS. The statistical analysis shows a decrease in the numbers of events during the last five years, which indicates improved dam safety within the mining industry. The analysis also shows that severe events and the human factor might be related when it comes to the initiating cause of the event. Further relations between the parameters and the severity of the events can be seen from the PLS-analysis, for example that low and short tailings dams to a greater extent are subjected to severe events. To be able to draw more reliable conclusions further studies with a more complete basic data are needed.</p><p>This work has shown a need of a collective database within the Swedish mining industry for tailings dams and occurring events at tailings dams so that more complete basic data could be obtained for future studies. A structure for such a database has been developed in Microsoft Access 2000. The aim of the database is to facilitate feedback within the mining industry and to gather comprehensive data for future statistical evaluations.</p> / <p>Vid alla gruvprocesser skapas stora mängder restprodukter i form av gråberg och anrikningssand som måste tas om hand på lämpligt sätt. Anrikningssanden deponeras tillsammans med vatten från gruvprocessen i magasin omgärdade av dammvallar, s.k. gruvdammar. Gruvdammar har som syfte att hålla kvar anrikningssand och vatten och måste vara stabila så att de skyddar omgivningen från utsläpp av anrikningssand som skulle kunna vara skadligt för miljön. En gruvdamm byggs ofta upp i etapper eftersom byggkostnaderna och behovet av dammfyllnadsmaterial då sprids över tiden.</p><p>Syftet med arbetet har varit att sammanställa och utvärdera händelser vid svenska gruvdammar samt att utforma ett för gruvindustrin gemensamt dammregister och felrapporteringssystem.</p><p>60 händelser vid svenska gruvdammar har sammanställts och utvärderats. Utvärderingen har genomförts dels genom att enskilda parametrar jämförts och analyserats och dels med hjälp av den multivariata analysmetoden PLS. Den statistiska analysen visar på en minskning i antal händelser under de senaste fem åren, vilket tyder på ett förbättrat dammsäkerhetsarbete inom gruvindustrin. Analysen har kunnat uppvisa ett samband mellan allvarliga händelser och den mänskliga faktorn när det gäller vad det är som initierat händelserna. Genom PLS-analysen har ytterligare samband mellan de undersökta parametrarna och allvarlighetsgraden av händelserna kunnat utläsas, bl.a. visar analysen att låga och korta dammar i större utsträckning drabbas av allvarliga händelser jämfört med höga och långa dammar. För att säkra slutsatser ska kunna dras krävs dock vidare studier med ett mer komplett statistiskt underlag.</p><p>Examensarbetet har påvisat ett behov av ett branchgemensamt damm- och felrapporteringsregister för att ett mer komplett underlag ska kunna erhållas i framtiden. En färdig databasstruktur för ett sådant dammregister och felrapporteringsregister för svenska gruvdammar har utformats. Databasen är uppbyggd i Microsoft Access 2000 och är tänkt att underlätta erfarenhetsåterföring inom branschen samt att ge ett underlag för framtida statistiska undersökningar.</p>

Rare earth mineral recovery from alternative resources such as coal and coal byproducts is increasingly important to provide an opportunity for economic recovery from U.S. sources. Currently, China produces the majority of the 149,000 tons of rare earth elements used annually worldwide of which the U.S. imports 11% or around 16,000 tons. There are no significant mining operations producing rare earth elements in the U.S. However, there are many U.S. sources containing rare earth minerals such as monazite including heavy mineral sand and phosphate operations. Monazite mineral particles of a few microns have also been detected in Fire Clay seam coal. Preliminary attempts to concentrate the rare earth mineral using flotation test results indicated that monazite was floated together with carbonate minerals. The flotation chemistry of a monazite-carbonate mineral system has received limited attention by researchers. As such, a systematic study of monazite flotation chemistry was conducted and the results reported in this dissertation. The surface charging mechanisms of monazite in aqueous systems were studied using electrokinetic tests, solution equilibrium calculation, crystal structure analysis, and electrostatic model prediction. The surface charge of monazite was found to be developed by protonation/deprotonation reactions. In other words, the hydrogen and hydroxyl ions were potential determining ions instead of the lattice ions of monazite. Electrokinetic tests of natural monazite mineral showed that the isoelectric point (IEP) occurred at pH 6.0. Solution equilibrium calculation and electrostatic model predictions of cerium monazite (CePO4) yielded an IEP of pH 7.2. The discrepancy between the two IEP values may be due to the different REE composition and/or the amount of carbon dioxide dissolved in solution. A common collector used to produce a hydrophobic monazite surface is octanohydroxamic acid. Adsorption studies found multilayer formation of octanohydroxamic acid on monazite surfaces at pH values of 3.0, 6.0, and 9.0. A kinetic study showed that the maximum adsorption density and rate for below monolayer coverage occurred at a solution pH value of 9.0, which was attributed to the chemical reaction between octanohydroxamate species and surface active sites (e.g., REE(OH)2+). For beyond multilayer adsorption, maximum adsorption occurred at pH 11.0 due to the abundance of hydroxyl ions in solution. The contributing effect of hydroxyl ions was proven by titration tests and FTIR analyses. When calcium ions existed in solution, specific adsorption of Ca(OH)+ on monazite surfaces occurred in both neutral and basic environments as indicated by the electrokinetic results. At low concentrations, Ca(OH)+ competed with octanohydroxamic acid for P-OH sites. However, higher dosages of Ca(OH)+ served as active sites for octanohydroxamic acid. The monazite floatability was negatively affected by the hydration of the adsorbed calcium species. The calcium ion dissolved from calcite mineral surfaces, which exist in the coal sources, provided an explanation for the depression of monazite in the combined systems. Single mineral flotation of monazite and calcite showed that sodium silicate and sodium hexametaphosphate efficiently depressed calcite while providing minimal effects on monazite recovery. However, in the monazite-calcite combined system, both monazite and calcite were depressed using the two regulators. Electrokinetic data and solution equilibrium calculations indicated that hydrolyzed species of calcium such as Ca(OH)+ interacted with silicates and formed a compact hydrophilic layer on monazite surfaces by hydrogen bonding and surface reaction. The compact layer decreased collector adsorption due to steric hindrance. Using 6×10-5 M EDTA together with 2.5×10-4 M octanohydroxamic acid and 0.05 g/L sodium silicate, monazite recovery of more than 90% was achieved while only recovering 20% of calcite. Based on the fundamental study, rare earth concentrates with 4700 ppm of REEs were produced from the Fire Clay fine coal refuse using column flotation.

Roman military equipment has traditionally been studied from a typological perspective based on a linear concept of change. Whilst Roman alloys have been analysed scientifically and general studies on them have been published, analysis of military equipment has been scarce and mostly secluded as part of excavation reports of individual sites. Scientific analysis though, can provide independent ways of studying military equipment. It can answer questions about production and distribution of the raw materials and finished objects and is capable of informing on reasons for technological choices (the intention of obtaining determinate colours, for example), and identification of military units. A total of 216 copper-alloy military objects from the British sites of South Cadbury Castle, Ham Hill, Usk, Carlisle, Chester and Kingsholm, and the German site of Kalkriese were selected for obtaining metallurgical characterisation: chemical analysis at major, minor and trace element level and microstructural analysis to obtain fabrication history and identifying any plating. The analytical techniques employed were atomic absorption spectrometry (AAS), scanning electron microscopy with energy dispersive x-ray spectrometry (SEM-EDS), optical microscopy and multivariate statistics methods such as principal component analysis (PCA), discriminant analysis (DA) and multivariate analysis of variance (MANOVA). The aim of the project was to characterise the chemical and physical make-up of Roman military copper-alloy metalwork from the 1st century AD, with especial interest in the immediate post-conquest period. The results of the analysis show a difference between the Roman military equipment from British sites and the equipment from Kalkriese, based on trace element patterns. This difference can be explained by a large input of material into Britain that had been made in the years before AD43 in preparation for the conquest. Contrary to recent scholarship, and based on compositional and microstructural evidence, some lorica segmentata brass fittings seem to have been centrally produced. Primary brass and specific gunmetal compositions seem to be associated with the military and probably chosen primarily for their appearance and resemblance to gold, rather than for their mechanical properties. The possibility of mechanised production of brass is explored based on the brass ingot from Sheepen.

Orientador: Rafael Alves Orsi / Banca: Renata Medeiros Paoliello / Banca: Frederico Daia Firmiano / Resumo: Entre os anos de 2000 e 2010 o setor mineral se tornou um dos mais importantes da economia brasileira, impulsionado pela demanda do mercado mundial e com o apoio do Estado por meio de volumosos repasses de recursos públicos e proposição de legislações. Apesar do avanço e a importância que o setor mineral passa a exercer na economia, este não se transformou, por sua vez, em um crescimento sustentável e um desenvolvimento endógeno para o país. Este trabalho tem o objetivo de compreender como a atividade mineral organizada mundialmente por meio das Indústrias Extrativas Minerais (IEM) transnacionais materializam suas atividades no território e quais são os impactos sociais, ambientais e econômicos desta atividade. Para esta finalidade propomos um estudo do pólo mineroquímico no município de Cajati, sendo este o maior do Estado de São Paulo. A proposta metodológica inicia-se com uma revisão sobre desenvolvimento desigual dos territórios a partir das mudanças econômicas mundiais e das agendas de governo. Em um segundo momento, analisamos as especificidades do modelo da extração mineral relacionada à localidade, à questão ambiental por se tratar de recursos não renováveis e com alto grau de degradação ambiental, e a questão legislativa. E por fim, realizamos um estudo de caso sobre o pólo mineroquímico de Cajati, desenvolvendo incursões a campo nas quais foram possíveis a utilização dos recursos fotográficos para registros e a realização de entrevistas semiestruturadas com o objeti... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Between the years of 2000 and 2010, the mineral sector become one of the most important of the brazilian economy, driven by the demand of world market and with support from the State by means of bulky transfers of public resources and the proposition of the legislations. Despite of the advance and the importance that the mineral sector starts exercise on the economy, this do not reflected, in its turn, in a sustainable growth and in an endogenous development to the country. This research has the objective of understand how the worldly organized mineral activity materialize its activities in the territory e who are the social, the environmental and the economics impacts of this activity. For this purpose we propose a study of the chemical mining pole in the county of Cajati, the biggest chemical mining pole of Sao Paulo State. The methodological purpose starts with a revision about the uneven development of the territories from the world economic changes and the government agenda. In a second moment, we analyze the specificities of the model of mineral extraction related to the locality, the environmental question to be treated of non-renewable resources and the legislative question. As also it present innumerable conflicts with the local communities, a strong concentration of lands and a high grade of environmental degradation. Finally, we carried out a case study on the Cajati mining area, developing field trips in which it was possible to use photographic resources for reco... (Complete abstract click electronic access below) / Mestre

A Thesis presented to the Department of Geophysics of the University of the Witwatersrand, Johannesburg / Violent failure of the rock surrounding under ground excavations forms a major hazard and obstacle in deep-level mining. (Abbreviation abstract) / AC 2018

A thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy. Johannesburg, September 2016 / The aim of this research was to investigate the bord and pillar design procedure in use at the time on chrome and platinum mines and subject it to a critical appraisal and, if necessary, propose an improved methodology. An analysis of the current method and some of the alternatives proposed in the literature has shown that the methodologies suffer from drawbacks that can be detrimental to the mining industry due to overdesign or rendering an excavation unsafe. The conclusion was that improvement is essential. The influence of the variability of the rock mass properties input parameters on the factor of safety in the current equation was calculated and the findings were that the value of the factor of safety can vary by up to 30 percent due to these variation. The proposed process adopted FLAC2D Hoek-Brown simulations to develop full stress deformation curves for typical pillars. The mine stiffness concept was introduced to determine the pillar load which automatically included the influence of the pillar and strata stiffness, excavation spans, pillar yield and failure. The factor of safety was obtained by dividing the pillar strength by the stress value of the intersection point of the two linear equations for the stiffness of the system and the pillar respectively. The proposed methodology was calibrated by applying it to two mines in the Bushveld. The conclusion was that the methodology is a significant improvement over the one in use. It was shown that a combination of the FLAC2D Hoek Brown and the System Pillar Equilibrium Concept can predict the extent of the fracture zones and, to certain extent, the pillar stresses. The stage has been reached where the methodology can be used to predict the most likely commencement of failure of pillars at greater depth and alternative pillar mining methods can be modelled. / MT2017

Master of Science in Engineering by advanced coursework and research: A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering Johannesburg, 2016 / The mining sector plays a significant role in the economy of Zimbabwe. The mining sector is the second largest contributor to the country’s GDP at over 20%. Zimbabwe as a country is endowed with abundant mineral resources. The top three commodities in terms of estimated resources are iron ore, coal and platinum with resources of 30 billion tonnes, 26 billion tonnes and 2.8 billion tonnes respectively. Zimbabwe’s vast mineral resources and reserves are of strategic importance to the Zimbabwe economy. Coal mining is one of the major economic contributors to the mining industry in Zimbabwe. The purpose of the study is to determine the optimal operational model for Makomo Resources from a mining and processing point of view. The study is based on a coal-mining project in the Zimbabwean mining industry. Makomo Resources is the largest privately owned coal mining company in the country, which has a mining licence to perform coal-mining activities in the north-west part of the Bulawayo Mining District of Zimbabwe. Makomo Resources applies a conventional strip mining method by means of truck and shovel to extract the coal reserves. Makomo Resources is supplying over 200,000 tonnes of coal per month to the local and export market. The mine has invested in USD20 million capital to commission a wash plant. The study investigates how to optimise the plant throughput by comparing two mining options: Mining Option 1 - crush and screen 2m power coal, crush & screen and wash a full 7m low ash coal seam and wash 2m of coking coal. Mining Option 2 – crush and screen 2m power coal, crush & screen a 3m low sulphur coal seam and wash low ash coal and coking coal of 4m and 2m respectively. The study investigated all the marketing, geology, mining and financial parameters in the Zimbabwean coal mining context. The study determines the appropriate mining methodology and explore to optimise the coal processing. Two financial models were developed to evaluate and compare the two proposed mining options, determine their feasibility and conclude the optimal mining model. Financial techniques were used to analyse and evaluate the two mining options. The financial models were used to analyse and evaluate the following:  The cashflow over the 10-year period.  The Net Present Value (NPV) and Internal Rate of Return (IRR) of each mining option.  The payback period of the washing plant.  Profitability Index per mining option. The NPV of a project determines the economic value of the mining project. The decision on a mining investment is mostly related to the NPV and IRR of the project. Discounted Cash flow (DCF) models were developed for both mining options that shows project cash in and out flows and calculates economic indicators, such as IRR and NPV. The NPV and IRR were the main methods for the evaluation of the two mining options. The resulting DCF models were developed in an Excel spreadsheet format designed for a 10-year Life of Mine (LOM) period. Mining Option 1 has a higher NPV of USD38.2 million in comparison to USD9.7 million for Mining Option 2. The IRR for Mining Option 1 was calculated at 48%, which is bigger than the IRR for Mining Option 2 of 26%. Mining Option 1 has a simple payback period and discounted payback period of 2.7 years and 4.9 years respectively. Mining Option 2 has a simple payback period and discounted payback period of 3.9 years and 11.9 years respectively. Mining Option 1 has a shorter payback period than Mining Option 2. Both mining options have a Profitability Index (PI bigger than one with Mining Option 1 and Mining Option 2 recording values of 1.87 and 1.18 respectively. Mining Option 1 has the better PI value and is therefore more profitable. Based on the economic evaluation, Mining Options 1 is by far more attractive than Mining Option 2, which results in a better return on the investment and profitability, therefore the preferred option. / MT2017

A saúde e segurança do trabalhador em um empreendimento mineiro necessitam de atenções redobradas. O constante monitoramento dos agentes físicos e químicos, possivelmente danosos, deve ser feito para que seja demonstrada eficiência nas medidas preventivas e até mesmo para que novas situações de risco sejam detectadas. Este monitoramento deve ser feito por profissionais preparados, que podem ser os próprios funcionários da empresa, desde que devidamente capacitados. As informações necessárias para o treinamento desses profissionais encontram-se dispersas em diferentes literaturas. O objetivo deste trabalho é elaborar um guia unificado de procedimentos de amostragem e tratamento de dados por meio de descrição dos agentes, instrumentação utilizada e exemplos de medição de campo, com metodologias específicas. Os resultados obtidos foram tratados, analisados e comparados com a respectiva norma brasileira vigente. Foram considerados os principais agentes nocivos de uma pedreira: ruído, iluminação, sílica, vibração e calor que foram analisados com alguns dos diversos instrumentos disponíveis no mercado. Este guia, com as sugestões de monitoramento, pode ser aplicado a outros ambientes de mineração. Os resultados são parâmetros na elaboração de melhorias para a saúde e a segurança dos trabalhadores. / Health and safety of mining workers require extra attention. The continuous monitoring of physical and chemical agents, possibly harmful, is essential to verify the efficiency of preventive actions and to identify new risks situations. This job has to be carried out by qualified professionals that can even be the company\'s employees, since well trained. However, the required information for guidance is not easily found at the specific bibliographies. Thus, the goal of this work is to prepare a comprehensive guide of field measurements with some sampling tips, including the description of the physical and chemical agents, equipments examples, and the associated methodology. The results were analyzed and compared with the current Brazilian standards. This study considered the most harmful agents in a quarry: noise, illuminance, silica dust, human vibration and heat stress which were measured with some of the several equipments available in the market. This guide, with suggested monitoring practices, can be extended to other mining environments. The results were helpful in proposing enhancements to safety and health of miners.

Systematic back analyses of cross sections through landslipped slopes in Barton Clay have been carried out, based on the both published (cross sections) and unpublished (piezometer) data. The results of these support earlier (Barton, 1973) rather than later (Barton and Garvey, 2011) interpretations. Ring shear tests on clay samples from these landslides show braod agreement with the back analyses. Further back analyses on landslide elements at Herne Bay in the London Clay throw additional light on the behaviour of landslides there. The remaining coastal landslide case histories in London Clay are reviewed. The body of case records compiled by James (1970) for infrastructure (railway) cutting failures in London Clay is reviewed, with new back analyses. These show clearly the deficiencies in that set of analyses on which several important papers were based. Further reinterpretation and analysis goes some way to resolving questions arising from the review. It is concluded that the back analysis technique is a useful one, and when applied correctly provides excellent general agreement with equally careful laboratory testing for extracting the shear strength parameters for a week bed forming the bedding-controlled basal shear of a compound landslide is presented and used. The analyses and tests are supported by a review of publoshed residual strength properties for British clays.

The introduction of ceramic matrix composites (CMCs) for structural applications in the hot section of a gas turbine provides many potential benefits over conventional alloy materials, including facilitating elevated operating temperatures. The development of an oxide-oxide CMC composed of commercially available Nextel 720 (3M) fibres within a porous alumina matrix was presented. A simple, low cost processing method involving slurry impregnation and subsequent consolidation and densification was developed, facilitating the production of dried pre-impregnated fabric (‘pre-preg’) that can be stored in ambient conditions. Detailed investigation into the effect of three types of PVA binder, the effect of 0-20wt% additions of an alumina precursor (ACH), the influence of a bimodal particle distribution and the effect of sintering at temperatures between 1100 and 1300°C on processing and mechanical properties was completed in order to optimise the material. The optimised composite material, composed of Nextel 720 fibres within a submicron alumina particle matrix with 10wt% ACH sintered at 1200°C, exhibited mean flexural strength >205MPa, short beam shear strength >12MPa and tensile strength >146MPa. These results were comparable to similar oxide CMCs previously reported, validating this material.