Respirable coal mine dust (RCMD) continues to pose serious health hazards to workers. Over the past few decades, new regulations, monitoring technologies, and improved dust controls have emerged, and all are based on the presumption that limiting RCMD on the basis of mass will effectively mitigate the exposure hazards. Given the latency of exposure outcomes, it will be some time before the full impact of these strategies can be evaluated. In the meantime, there is increasing awareness that RCMD particle characteristics, in addition to mass, might be important. This dissertation comprises four separate studies which explore the effects of primary RCMD sources and/or engineering controls on particle size and constituents. To enable a direct comparison of dust generation from primary dust sources, a field study was conducted to investigate the dust generation and particle characteristics between coal and the rock strata. Results indicated that finer and more dust was generated when mining predominantly into the rock strata versus the coal strata, while the operation of a flooded bed scrubber and an increase in water sprays pressure and volume generally suppressed dust. Prior government research, conducted within the Mining Research Division of the National Institute of Occupational Safety and Health (NIOSH) evaluated the dust mass concentrations removal efficiency of different dust controls (i.e., a dry and wet scrubber, canopy air curtain, and a wet versus dry dust collection boxes). In the second and third studies, preserved samples from these prior NIOSH dust control studies were re-analyzed and evaluated to understand their effects on dust characteristics. Results indicated that the efficiency of dust controls was particle size dependent, as these controls mostly showed no appreciable effects on dust constituents. Generally, the cleaning of dust from a novel wet dust collection box versus a traditional dry dust box led to a reduction in operator exposure to hazardous dust. In the final study, a laboratory prototype flooded bed scrubber was evaluated to understand its efficiency on dust between different particle size bins (i.e., by particle count) ranging from 0.3-10 µm. From the results, removal efficiencies were generally low – and sometimes negative, for dust particles mostly in each of the size bins less than 2 µm. The results presented here highlight the need to holistically evaluate dust controls to understand their efficiency on dust of different particle sizes and constituents, so that informed decisions can be made on the best controls to adopt in mine operations. / Doctor of Philosophy / Coal production contributes significantly to steel making and electricity generation in the US. During the mining process, very fine dust is generated—called "respirable" dust— which represents a significant health hazard to workers. Indeed, many cases of occupational lung diseases linked to respirable dust have been reported over the past few decades, and disease rates remain high. Dust monitoring and control efforts are largely based on limiting the total mass of respirable dust. However, there is growing evidence that specific types of dust present disproportionate hazards—including the smallest particles, which do not contribute much to total mass, and mineral particles such as silica. The research in this dissertation explores the effects of primary dust sources and controls on respirable dust size and constituents. The major findings are as follows: when using typical equipment, mining into the rock strata that surrounds the target coal seam can generate much more dust than mining the coal itself. This dust generated can be finer and contain more mineral dust like silica and silicates. Furthermore, most dust controls used to suppress dust do not appear to be selective with respect to particle type but are generally less efficient for removing finer particles. This implies that, while dust mass removal efficiency may be high, controls might still be needed where very fine dust particles pose substantial hazards. Additionally, mine operations could develop monitoring techniques and re-orient their dust controls to target and better mitigate the most hazardous primary sources of dust such as dust from the rock strata.

The purpose of this study is to examine how Viking Line, Tallink Silja and Birka Cruises work with economic and environmental sustainability, and also to see how they work with new environmental legislations. In 2015 a new environmental legislation will be introduced, by the name Sulphur directive. The Sulphur directive entails a reduction in Sulphur dioxide emissions from ships where the emissions cannot exceed 0,1 percent. There are three alternatives to achieve the new environmental legislation, the use of Marine Gas Oil, LNG or scrubbers. All three alternatives will lead to increasing costs for the shipping industry. The three companies exerts its shipping traffic in the Baltic Sea, a sea that is highly sensitive to external impacts. In the study qualitative methods were used, three personal interviews and five telephone interviews. Five theories were used to understand how the companies work, their estimations and their decisions: Strategic Tourism Planning Process, the Triple Bottom Line, the COSO model, The Decision-making Process and Responsible Cruise Tourism. The results of the study show that all three companies are facing an uncertain economic sustainable future and the deciding factors will be technological development, fuel prices and competitiveness.

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Arbetet som utförts är en material studie som inriktar sig på nickel-krom-molybdenbaserade legeringar som används i dagens våt skrubber. Eftersom kraven på mängden utsläpp av svaveldioxid är en viktig miljöfråga, skapar detta ett behov för användandet av en våt skrubber. Den här produkten befinner sig i anläggningar där förbränningsmotorer finns och förekommer i princip i alla större fartyg. Rökgasen som motorerna släpper ifrån sig är skadlig för miljön och därför absorberas flödet in till en våt skrubber där en förbränning sker. Rökgasen separeras med hjälp av ett antal sprinklers som är placerade ovanpå gas ingången i en skrubber. Med hjälp av havsvatten som samlas upp och sluts till skrubbern injiceras detta genom sprinklers sen vidare nedåt på rökgasen som separerar föroreningar ifrån den gasen som är tänkt ska kondensera genom och ut i atmosfären. Havsvatten tillsammans med föroreningarna samlas på botten av skrubbern och samlas i tankar. Denna miljö är väldigt skadlig för materialet som produkten består av, framför allt på botten där materialet riskerar att korrodera som mest. Arbetet beskriver ett antal typer av korrosion och förklarar innebörden av de olika typerna så att det enklare går att förstå sammanhanget med miljön och omständigheternas påverkan på legeringarna. Syftet i arbetet är att studera de olika legeringarna och beskriva de med hjälp av den litteraturstudie som gjorts. Med hjälp av insamlad data av tester som tidigare utförts enligt standard, har detta tolkats och bidragit till evalueringen av de olika legeringarna. De grundläggande tester som används vid evaluering av legeringarnas karaktär är tester där en bit av materialet doppas ned i en specifik lösning med olika omständigheter och villkor. Detta räcker inte för att säkerställa en hållbar livscykel för en våt skrubber och därför evalueras legeringarna även med hjälp av olika fälttester. Teoretiska studier på tester i aggressiva miljöer används för att resultera rangordningen av de olika materialen och även ett nytt material undersöks vid namnet alloy 2120. / This thesis work is a study of materials which focus on nickel-chromium-molybdenum-based alloys used in today’s wet scrubbers. Since the requirements for emissions of sulfur dioxide is a major environmental issue, this creates a need for the use of a wet scrubber. This product is in installations where combustion engines are available and are basically in all larger vessels. The flue gas that engines emit are harmful to the environment and for that reason, the flow is absorbed into a wet scrubber where combustion takes place. The flue gas is separated by a number of sprinklers placed above of the gas in a scrubber. Collected seawater is used to separate the gas through the sprinklers that injects the water on top of the flue gas where impurities is separated from the gas that will condense out to the atmosphere. The water fluid together with the contaminants is collected on the bottom of the scrubber and into the tanks. This environment is very harmful to the material that the product is made of, in particular on the bottom where the material is more susceptible for corrosion. The work describes several types of corrosion and the meaning of the different types so that the reader easily can understand the impact of the environment on the alloys. The type of corrosion that occurs primarily in scrubbers is pitting corrosion and is considerate to be a highly local type of corrosion, and the most dangerous type. Pitting occurs when the protective oxide layer does not have time to repassivate and can also lead to other types of corrosion. Due to the dangerous work environment, the risk for corrosion to occur is high and therefore, focus is put on this specific material group. The purpose of this work was to study the alloys and describe them with the help of a literature study. Using data collected from tests previously performed in accordance with standards, the collected data has been interpreted and contributing to the evaluation of the various alloys. The basic tests used in the evaluation of the nature of the alloy are tests in which a piece of material immersed in a specific solution with different circumstances and conditions. This is not enough to ensure a sustainable life cycle for a wet scrubber and therefore, alloys is evaluated using various field tests as well. Theoretical studies on tests in aggressive environments is used to result the ranking of the various materials and also a new material is examined by the name alloy 2120.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Venturi scrubbers are simples, low cost and highly applicable equipments. They are used in the industry as gas cleaners and in other to control the pollution. The objective of this work was to evaluate a gas cleaning system using Venturi scrubbers with circular section to remove particles off a gas flux. The tests were realized with 2,21 and 9,06 μm particles of phosphate power. The global collection efficiency was determined for 55,2 and 76,8 m/s of gas velocity, 340 and 500 mL/min of liquid flow and for 99 and 132 mm of length throat. From an experimental design 24 it was obtained that all variables studied and the gas velocity´s interaction with liquid flow and with length throat had influence over the collection efficiency. For 2,21 μm particles the efficience range was from 53,8 to 86,8% while for 9,06 μm particles it was from 53,4 to 96,5%. The results´ analysis showed that as bigger the gas velocity and the liquid flow are, higher the efficience gets. It happens because there are more quantity of washing liquid to be atomized with the liquid flow increase. This atomization gets better with high gas velocities taxes. Another point observed was that for longer length throat and higher gas velocity, the collection efficiency grows. What occurs here is that the particles´s residence time inside the throat was bigger for 132 mm length throat than for 99 mm. And more time, a gas acceleration resulted on better jet´s atomization. The study of different particles sizes showed that 9,06 μm were removed more efficiently than particles with medium diameter of 2,21 μm. Particles with bigger diameters present more inercia, which facilitates the action of the inercial impaction, the collection mechanism that predominates in Venturi scrubbers. The jet penetration was another parameter analysed and it represented the expected behavior: as bigger the liquid flow gets and lower the gas velocity, higher was the jet penetration length. The experimental results of global collection efficiency were compared with theorical models like JOHNSTONE et al. (1954), CALVERT et al. (1972) and modified CALVERT (RIBEIRO, 2005). CALVERT et al. and modified CALVERT models overestimated the values of dust collection efficiency and although JOHSNTONE et al.´s model has underestimated those values, it was the one that better fitted the experimental results, because it showed that the collection efficiency was higher for highs gas velocities. / O lavador Venturi é um equipamento simples, de custo médio baixo e bastante eficiente, aplicado na remoção de material particulado e no controle da poluição. O objetivo deste estudo foi avaliar um sistema de limpeza de gás utilizando lavadores Venturi de seção circular na remoção de partículas de uma corrente gasosa. O material particulado usado nos testes foi o concentrado fosfático, com diâmetros médios de 2,21 e 9,06 μm. Eficiências globais de coleta foram obtidas realizando-se experimentos com velocidade do gás de 55,2 é 76,8 m/s, vazão de líquido de 340 e 500 mL/min e comprimento de garganta de 99 e 132 mm. Um planejamento experimental 24 foi feito e verificou-se que todas as variáveis e as interações da velocidade do gás com o comprimento da garganta e com a vazão de líquido tiveram efeito na remoção de partículas da corrente gasosa. A coleta das partículas de 2,21 μm apresentou uma faixa de eficiência de 53,8 a 86,8%, enquanto 53,4 a 96,5% de remoção foram identificadas para as partículas de 9,06 μm. A análise dos resultados mostrou que, como conseqüência de aumentos na velocidade do gás e na vazão de líquido, a eficiência de coleta crescia, já que quanto maior a vazão do líquido de lavagem maior a quantidade de água para ser atomizada, atomização essa que também aumentava com velocidades de gás mais altas. Outra observação foi que, com o aumento do comprimento da garganta e da velocidade do gás, o percentual de remoção de rocha fosfática era maior, uma vez que o tempo de contato entre o pó e o líquido crescia com uma garganta mais comprida e o aumento da velocidade do gás proporcionava, mais uma vez, melhor atomização do jato. Em relação aos diferentes tamanhos de partículas, notou-se que as de diâmetro médio de 9,06 μm eram removidas do fluxo de gás com mais eficiência que as de 2,21 μm, pois partículas de diâmetro maior têm maior inércia, o que favorece o mecanismo de coleta de impactação inercial, predominante em lavadores Venturi. Os resultados experimentais de eficiência global de coleta ainda foram comparados com os modelos teóricos de JOHNSTONE et al. (1954), CALVERT et al. (1972) e CALVERT modificado (RIBEIRO, 2005). O modelo de JOHSNTONE et al. subestimou os valores experimentais de coleta, enquanto os outros dois modelos superestimaram. Ainda assim, o modelo de JOHNSTONE et al. foi o que apresentou melhor ajuste, porque seguiu a tendência de aumento da eficiência de coleta em função de um acréscimo na velocidade do gás. / Mestre em Engenharia Química