Orientador: Marco Aurélio Zezzi Arruda / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-22T10:57:39Z (GMT). No. of bitstreams: 1 Galazzi_RodrigoMoretto_M.pdf: 2262907 bytes, checksum: fb6e92051f6858cd925c525071ce6540 (MD5) Previous issue date: 2013 / Resumo: Nessa dissertação, otimizou-se um método para a determinação de estanho (Sn) em amostras biológicas empregando a técnica de Espectrometria de Absorção Atômica por Geração de Hidretos e Forno Metálico (MF-HG-AAS, do inglês Metallic Furnace Hydride Generation Atomic Absorption Spectrometry). Foram avaliadas algumas variáveis químicas como o tipo e concentração do carregador/diluente da solução padrão, concentração do redutor tetraidridoborato (-1) de sódio (THB) e concentração de hidróxido de sódio, bem como variáveis físicas do sistema dentre elas a vazão de carregador, proporção de acetileno:ar na chama, volume de solução injetado, vazão de argônio como gás de arraste, vazão de água no nebulizador e área total de furos no tubo metalico Inconel600®. Foi realizado um estudo do efeito de memória observado em condições de chama oxidante nas vazões de 1,5:9; 1,4:9; 1,3:9; 1,4:10; 1,4:8 e 1,5:11 L min de acetileno:ar, respectivamente. Em todas essas proporções de chama diferentes da otimizada (1,5:10 L min acetileno:ar) há efeito de memória, o que é extremamente indesejável. Após a otimização do sistema, foram realizados testes de exatidão e precisão do mesmo com os materiais PACS-2 (sedimento) e SRM 1643e (amostra de água) em que, em ambos, foi possível recuperar o Sn adicionado obtendo limites de detecção (LD) de 7,1 mg kg e 7,6 mg L, respectivamente. Um estudo com concomitantes foi realizado para avaliar se algum dos elementos em questão poderia interferir na determinação do Sn. Foram estudados como possíveis concomitantes o cobre, chumbo e zinco em três níveis diferentes. Somente o cobre, nas razões de 1:10 e 1:20 (Sn:concomitante), interferiu na detecção de Sn. Por fim, a morfologia do atomizador foi avaliada por meio da técnica de Microscopia Eletrônica de Varredura (SEM, do inglês Scanning Electron Microscopy). Mesmo após a realização de todos os experimentos envolvendo a otimização do sistema e análise das amostras, os principais constituintes do tubo metálico Inconel600® (ferro, níquel e cromo) permaneceram homogeneamente distribuídos, indicando que esses metais podem não participar da rota de atomização do Sn. Além disso, houve formação de óxidos no atomizador que, juntamente com o uso de uma chama oxidante, sugerem uma rota de atomização do Sn via formação de óxidos. Considerando os LD, bem como a exatidão e precisão por meio da recuperação de Sn obtida nas amostras, constata-se a potencialidade da MF-HG-AAS frente a outras técnicas empregadas na determinação de Sn / Abstract: In this work, a Metallic Furnace Hydride Generation Atomic Absorption Spectrometry (MF-HG-AAS) was optimized for tin (Sn) determination in biological samples. Chemical variables, such as the type and carrier concentration, the sodium tetrahydrideborate (-1) (THB), and the sodium hydroxide concentration, as well as physical variables, such as carrier flow-rate, ratio of acetylene and air in the flame, injection volume, argon flow-rate as carrier of stannane, water flow-rate in nebulizer and total hole area of a Inconel600® metallic furnace were evaluated. A study of a memory effect observed in oxidant flame conditions such as 1.5:9; 1.4:9; 1.3:9; 1.4:10; 1.4:8 e 1.5:11 L minof acetylene:air, respectively, was realized. In any other flame flow-rate, which the optimized flame ratio (1.5:10 L min acetylene:air) was observed a memory effect, which is very undesirable. After optimizing of the system, test of accuracy and precision were realized with the PACS-2 (sediment) and SRM 1643e (water sample) materials wherein, in both, a recovery of the Sn added to the samples was possible with limits of detection (LOD) as 7,1 mg kg and 7,6 mg L, respectively. A concomitant study was carried out for checking the interferences in the Sn determination. Copper, lead and zinc at three different levels were studied as possible concomitants. Only copper, at 1:10 and 1:20 (Sn:concomitant) ratios interfered in the determination of Sn. Finally, the morphology of the atomizer employed was evaluated through Scanning Electron Microscopy (SEM) technique. Even after carrying out all experiments involved in the optimization of the system and in the sample analysis, the main constituents of Inconel600® metallic furnace (iron, nickel and chromium) remained homogeneously distributed, indicating which these elements may not participate of the Sn atomization route. Moreover, the oxide formation in the atomizer was detected, which, together with an oxidant flame used, suggests the Sn atomization route via oxides formation. Considering the LOD, as well the accuracy and precision through the Sn recovery in the samples, the MF-HG-AAS potentially is well pointed out when it is compared to other techniques employed for Sn determination / Mestrado / Quimica Analitica / Mestre em Química

[pt] A metalurgia é a ciência que estuda os diversos meios para a transformação dos metais em materiais úteis à sociedade. A metalurgia do ferro representa a maior fatia da aplicação dos metais. Por ser tão representativa é chamada de Siderurgia. Dentre as diversas rotas para a transformação do ferro em aço, as usinas semi-integradas apresentam um forte apelo ecológico, pois utilizam a sucata, oriunda da reciclagem de ferro, e o ferro gusa como matérias-primas para a fusão no Forno Elétrico a Arco. Naturalmente, em todo processo industrial há a geração de resíduos e, neste caso, o principal é a escória, composta de óxidos formados e adicionados ao longo da fusão. Seus principais constituintes são: CaO, SiO2, FeO, MnO, MgO, Al2O3 e P2O5. No entanto, ainda há a presença de Ferro Metálico, um fato indesejável, pois atua negativamente no rendimento metálico e, consequentemente, aumenta o custo do aço. Toda escória gerada é beneficiada com o intuito de recuperar a parte metálica. Este material beneficiado retorna para as usinas como sucata metálica, contendo teores definidos de ferro metálico. O teor de ferro presente na sucata recuperada é avaliado pelas empresas processadoras de escória de maneira indireta por um ensaio de densidade específica. Havia dúvidas se a sucata recuperada da escória do forno apresentava teores de ferro que justificasse seu emprego como matéria-prima ferrosa. Assim sendo, foi proposta uma rota de processamento capaz de mensurar o teor de ferro presente e permitir a comparação com os teores obtidos com o ensaio de densidade. Os resultados mostram que i) é possível calcular o impacto no rendimento, ii) que as sucatas recuperadas apresentam valores inferiores ao esperado, iii) que a equação de densidade superestima o teor de ferro e iv) que modificações propostas nos coeficientes da equação vigente melhoram seu grau de assertividade. Estes resultados foram comprovados em 3 plantas siderúrgicas. / [en] Metallurgy is the science that studies the various processes for the transformation of metals into society useful materials. The iron metallurgy represents the largest body of the metals application, hence it is called Steel industry. Among the various routes for the transformation of iron into steel, semiintegrated plants have a strong ecological appeal due to their extensive use of scrap, derived from the recycling of iron, and pig iron as raw materials for the Electric Arc Furnace. Of course, industrial processes generate waste. The major waste of the Electric Arc Furnace is the slag, a mixture of oxides produced during the process, containing CaO, SiO2, FeO, MnO, MgO, Al2O3 e P2O5. However, there is also the presence of metallic iron, a fact undesirable, because it acts negatively on the metallic yield and therefore increases the cost of steel. All slag generated is processed in order to recover the metallic iron. The slag beneficiation returns to the mills a material containing defined levels of iron. The content of recovered iron is assessed by slag processing companies indirectly by a specific gravity test. There have been doubts whether the recovered scrap iron content justify its use as raw ferrous materials. Therefore, it is proposed a processing route capable of measuring the amount of iron present in the recovered scrap. The measured iron content is also compared with the levels obtained from the test density. The results show that i) it is possible to calculate the impact on iron yield, ii) the recovered iron content is lower than expected, iii) the density equation overestimates the amount of iron and iv) a correction is proposed to improve the assertiveness of the density equation. Three steel plants confirmed the results from this research.

<div>The objective of this research was to develop an efficient simulation of an industrial reheating furnace with a flexible scale formation model and to apply the models to study various conditions within an industrial reheating furnace. This work focused on developing a model capable of considering many different key variables that influence scale formation. The scale formation model was incorporated into the computational fluid dynamics (CFD) software ANSYS Fluent © to solve a coupled steady-state and transient simulation. It was also generalized for a low-carbon steel product, so it may not be adequate to cover the effects of alloying metals on the oxidation process. In order to verify the accuracy of these models, baseline cases were simulated and validated against both industrial data and findings from experiments in published literature.</div><div><br></div><div>A parametric study with two levels of oxygen enrichment implementation in only the preheat zone was undertaken to study the effects on the heat transfer, scale formation, and fluid flow within the reheat furnace. A medium oxygen enrichment case of 46 vol% oxygen and an oxy-fuel case were used for study. Both oxygen enrichment cases showed largely increased heat transfer to the slab in the preheat zone and increased scale formation. Based on these results, 46 vol% oxygen enrichment is recommended for use in a typical industrial reheat furnace with additional firing rate drawback to reduce scaling and to reduce the chance of overheating the steel slab product.</div>

The influence of electromagnetic stirring in an electric arc furnace (EAF) has been studied. Using numerical modeling the effect of electromagnetic stirring on the thermal stratification and fluid flow has been investigated. The finite element method (FEM) software was used to compute the electromagnetic forces, and the fluid flow and heat and mass transfer equations were solved using a finite volume method (FVM) software. The results show that electromagnetic stirring has a significant effect on temperature homogenization and mixing efficiency in the bath. The important part of this study was calculation of heat transfer coefficient. The results show, electromagnetic stirring improves the heat transfer from the melt to scrap which is dependent on the stirring direction and force magnitudes.

A common view in today’s society is that natural background conditions is found just prior to the start of the industrialization. By employing this view in environmental work, it neglects the human impact attributed to historical site-specific activities such as metallurgy. These activities have been widespread throughout Sweden, reaching far back into history. It is therefore necessary to determine the site-specific background conditions in order to assess the impact these activities have had. This study investigates the start of the blast furnace Alntorpshyttan in Bergslagen by conducting geochemical analyzes using sediment profiles in Norasjön as a natural archive. This was coupled with an indirect dating method based on the immigration spruce (Picea abies) and the historical atmospheric lead (Pb) pollution. The earliest sign of human activities takes place at 1800 BP, possibly due to farming activities. Based on the increases in iron coupled with increases in other ore-related elements (e.g., Magnesium and copper) I placed the start of Alntorpshyttan in the early/late 13th century. This is consistent with the rapid expansion of blast furnaces throughout Bergslagen. Based on these results, I conclude that historical small-scale metallurgical activities have had a significant impact on local lake systems and potentially a cumulative effect further downstream.

By partly replacing the use of primary energy sources with waste heat recovery, climate and environmental goals for the future will be closer at hand. This thesis investigates the waste heat potential of Alfa Laval’s vacuum brazing furnaces in Ronneby and alternative ways of integrating the furnace’s waste heat into the building’s HVAC system. The main challenge was the low-temperature qualities associated with the cooling water, which constituted an obstacle to recovering waste heat without any additional equipment, such as a heat pump. Tests and analyses performed in this thesis are, therefore, mainly aimed at raising the temperature quality of the cooling water. A test was conducted on the cooling system to calculate the energy losses with regards to the cooling water. In one 11-hour cycle, 1546 kWh of electricity was used to heat the furnace. Out of that, 1360 kWh was cooled off to the atmosphere. Additionally, a test on the furnace’s clean-up cycle was performed. The maximum cooling water temperature reached during this test was 44 C. This shows excellent potential in the possibility of recovering the waste heat without any additional equipment. Further, this thesis aims to broaden the knowledge around areas concerning increased cooling water temperatures, which, during the writing, seemed to have a gap in documented sources. The results of this thesis indicate that a temperature quality increase of the furnaces’ cooling water is possible. Cooling system changes have also been suggested, which is necessary for an efficient and safe heat recovery.

The main objectives of this study were to investigate (i) anovel wetland treatment technology and (ii) selected bed filtermedia for the removal of contaminants from landfill leachate. Areview of the literature concerning experiences of the use ofconstructed wetlands (CW) for the removal of nitrogen fromlandfill leachate, showed that at least three groups oftreatment systems are in practice: sub-surface flow wetlands,hybrid systems (a combination of vertical and horizontal flowwetlands) and, compact constructed wetland (CCW). Most of thesetypeswere generally effective in reducing nitrogen (N,e.g.NH4-N, dominant N species in leachate) down toeffluent concentrations of about 10 mg L-1. Unfortunately, very little evidence ofresponsible mechanisms for the removal of N was presented,although some data indicated denitrification. The treatmentperformance of a compact constructed wetland (CCW) applied atthe Tveta Landfill, Södertälje, Sweden, wasevaluated. Chemically purified leachate and untreated leachatewere applied in periods of 7 day submergence and 7 day drainageto different sections of the CCW. The removal efficiency variedbetween 40 and 82%, and a mass removal rate of up to 5.1 g m2d-1was achieved. The chemical pre-treatment had adecisive role for the highest removal efficiencies obtained andit was unclear whether that treatment enhanced the efficiencybecause of lower toxicity and/or content of fewer competingcations. The possible combination of bed filter media and CCWas an ecotechnological treatment method for landfill leachatewas investigated by bench-scale laboratory column experiments.Reactive filter media (sorbents) was selected from their knownor suggested capacities for removal of heavy metals, nitrogenand phosphorus. Quartz sand or natural sand from an esker wasused as reference medium. Peat was used as an additionalcomponent in mixtures with the reactive media Polonite®(product from the bedrock opoka) and blastfurnace slag (BFS). A small column study also involved zeolite.Phosphorus was efficiently removed by Polonite®and NH4-N to some extent. Concerning metal removal, thebest performance was found as well for Polonite®, especially for Mn, Fe, Zn and Cu. The BFSshowed good removal efficiency for Cu, Ni and Mo. The removalof different elements was suggested to be a combination ofseveral factors,e.g.precipitation, ion exchange and adsorption. Priorto full-scale application of reactive filters at a landfillsite, matrix selection, filter design and operationalprocedures must be developed. Keywords:Blast furnace slag; Compact constructedwetland; Metals; Nitrogen; Polonite; Sorbents

No description available.

The effect of gas stirring in the ladle furnace on inclusion content in austenitic and duplex stainless steel has been investigated at Sandvik Materials Technology AB. The effect was mainly investigated by varying duration of stirring time and intensity of stirring. Any effect on inclusion content was determined by examining total oxygen content before and after the ladle treatment, along with mapping the chemical composition, size and size distribution of the inclusions. Any effect on slag composition was also determined. The effect of gas stirring was measured on a number of heats with continuous sampling during normal production. Data regarding oxygen content during the ladle refining process and the duration of the processes was used to determine a quantifiable relationship between stirring time, stirring intensity and resulting change in oxygen content. The result of the investigation was recommendations regarding the use of varied stirring intensities and duration of gas stirring for achieving negative net loss in oxygen content before and after ladle treatment.

<p>The inclusions are harmful to the steel cleanliness; process parameters such as stirring and steel and slag oxidation must be controlled to obtain a final number of inclusions in the steel whose size is smaller than the critical size for each steel product.</p> <p>A simple mathematical model was developed to analyze the impact of bubbling, slag and initial oxidation level on inclusion distribution control (quantity and size of them) during the process in a Ladle Metallurgy Furnace (LMF).</p> <p>The initial inclusion size distribution is calculated and adjusted with the samples analyzed by SEM-EDAX, this initial distribution decreases by removal mechanisms such as bubbling and slag and they can increases by reoxidation.</p> <p>The model allows predicting the inclusion removal by bubbling mechanism as a function of gas flow rate and inclusion size and it proves which a softer stirring is better for removal inclusion than stronger one. An interesting point analyzed is the effect of stirring level on small and large inclusions.</p> <p>According to the inclusion number removal by slag, it is possible to appreciate like larger inclusions are removed easier than smaller ones. This mechanism is the most important to remove inclusions calculated by this model.</p> / Master of Science (MSc)