EM - Escola de Minas
URI permanente desta comunidadehttp://www.hml.repositorio.ufop.br/handle/123456789/6
Notícias
A Escola de Minas de Ouro Preto foi fundada pelo cientista Claude Henri Gorceix e inaugurada em 12 de outubro de 1876.
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Item Characterization of flotation tailings from Samarco and other varieties of sand for use in sand molding in the foundry industry.(2019) Figueiredo, Ricardo Augusto Martins; Oliveira, Sávio José de; Silva, Guilherme Francisco de Sales; Vieira, Cláudio Batista; Pinto, Maria Aparecida; Carneiro, Leandro Moreira; Seshadri, Varadarajan; Araújo, Denilson Rodrigues de; Vilela Neto, Gil RibeiroFoundry sand used for molding should have specific properties so that molds with adequate strength, porosity, etc to produce defect free castings. Thus, characterization of two types of flotation tailings from the mineral processing of itabirites and three types of base sand for molding have been carried out. The resulting properties have been compared to evaluate the suitability of use of typical flotation tailing for the molding process. The main properties determined are the grain shape and structure, chemical composition, grain size distribution, fineness modulus, fines content, moisture content and loss on ignition. Furthermore other properties of these sands prepared with binders have been compared like compactability, permeability and green compressive strength for green sand. For cold set and sodium silicate/CO2 processes properties like tensile strength and bending strength have been evaluated. The results show that the flotation tailing SA2 presented a good potential of use in the foundry.Item Analysis of the fluid flow behavior within a beam blank mold using submerged-entry nozzle with three exit ports.(2019) Gabriel, Weslei Viana; Peixoto, Johne Jesus Mol; Alves, Gesiane Letícia; Silva, Carlos Antônio da; Silva, Itavahn Alves da; Seshadri, VaradarajanThrough the use of physical and mathematical modeling techniques, liquid flow inside a beam blank mold with a submerged valve consisting of three exit ports has been analyzed. The behavior of the slag metal interface was evaluated using water and an aqueous NaCl solution to simulate steel. Slag simulation was done using silicon oil. Increased casting speed results in increased free surface oscillation. For the fluid density of 1,000 kg/m3, oil entrainment started at a casting velocity of 0.98 m/minute. For a fluid density of 1,170 kg/m3, no entrainment was observed in any of the conditions studied.Item The influence of flow asymmetry on refractory erosion in the vacuum chamber of a RH degasser.(2019) Melo, Pedro Henrique Resende Vaz de; Peixoto, Johne Jesus Mol; Galante, Gustavo Santos; Loiola, Bruna Helena Malovini; Silva, Carlos Antônio da; Silva, Itavahn Alves da; Seshadri, VaradarajanNozzle blockage in RH reactors is a serious operational problem since it can cause an asymmetric distribution of the steel flow in both the up-leg as well as the lower region of the vacuum chamber. This anomaly can alter the circulation rate in addition to affecting the erosion profile of the lower part of vacuum chamber refractory lining. In this study, the effect of nozzle obstruction on liquid circulation rate, wall shear stress, velocity profiles and flow pattern have been evaluated. In addition, refractory erosion in the vacuum chamber has been estimated through physical modeling and mathematical simulation results. Four blockage conditions were studied for different gas flow rates. There was a good agreement in physical and mathematical models results. Asymmetric flow was observed in vacuum chamber lower region in asymmetric blockage cases, which resulted in preferential wear on one chamber side in physical modeling experiments. The wall shear stress analysis in the vacuum chamber using a fluid dynamic model also indicates preferential erosion. When compared, refractory erosion results in physical modeling and shear stress in mathematical modeling presented good correlation.Item Numerical and physical simulation of the fluid flow in a beam blank mold fed through the center of the web.(2019) Gabriel, Weslei Viana; Peixoto, Johne Jesus Mol; Queiroz, Guilherme Santiago; Silva, Carlos Antônio da; Silva, Itavahn Alves da; Seshadri, VaradarajanFluid flow inside a beam blank mold fed through a three-port SEN (two lateral ports and one bottom port), positioned at the center of the mold, has been investigated. Literature survey shows that this kind of configuration is not frequently used. It had been shown that it is possible to get a symmetrical flow with this configuration. The downward inclination of the ports should influence the transient fluid flow. The greater the downward inclination, the greater is the instability of the jet and of the interface between the immiscible fluids that simulate the slag/metal behavior. The flow characterization was made by dye dispersion, PIV technique, measurement of the meniscus oscillation using ultrasonic sensors, and CFD simulations. The slag/metal behavior was simulated using water and oils with different physical properties. The results from PIV as well as from observations of the water–oil interface have been used to validate the CFD simulations. Oils with density close to water resulted in more instability at the interface with entrainment starting from fluid flow rate of 125 L/min (equivalent to casting speed of 1 m/min). Decreasing the viscosity of slag (oils) and increasing the casting velocity (water flow rate) result in reduction of the interfacial stability.Item Numerical simulation of recirculating flow and physical model of slag–metal behavior in an RH reactor : application to desulfurization.(2018) Peixoto, Johne Jesus Mol; Gabriel, Weslei Viana; Oliveira, Thiago Araújo Santos de; Silva, Carlos Antônio da; Silva, Itavahn Alves da; Seshadri, VaradarajanComputational fluid dynamics (CFD) techniques and a 1:7.5 physical model of an RH degasser have been used to evaluate the flow of gas and metal inside an RH reactor for vacuum degassing of liquid steel. The effect of gas injection on the gas spatial distribution, steel circulation rate and flow field inside the ladle, snorkels and vacuum chamber have been assessed. N-pentane oil was employed to evaluate the average residence time as well as the slag droplet size distribution. The predicted radial gas distribution and liquid circulation rate have been validated against experimental data from a physical model. The results with incorporation of the virtual mass force coefficient of 0.25 and the turbulence dispersion force showed better predictions of gas distribution in the up-snorkel as well as circulation rate. Full-scale simulations were performed, and the predicted circulation rate was significantly affected by the argon bubble expansion. Data from these simulations were used to analyze the degree of desulfurization performed by the addition of desulfurizing agents inside the vacuum chamber. A model of the kinetics of desulfurization based on the results from the physical model and CFD simulation and on slag dispersion inside liquid steel yields degrees of desulfurization similar to the industrial trials reported in the literature.Item Influência da configuração da SEN no comportamento fluidodinâmico em molde de Beam Blank.(2017) Gabriel, Weslei Viana; Peixoto, Johne Jesus Mol; Alves, Gesiane Letícia; Silva, Carlos Antônio da; Silva, Itavahn Alves da; Seshadri, VaradarajanUtilizando técnicas de modelagem física e matemática comparou-se o fluxo de fluido no interior do molde de beam blank alimentado por apenas uma válvula submersa, com 3 e 4 portas na saída respectivamente. Na válvula com 4 portas, observou-se que para um diâmetro da porta de saída inferior de 10mm não houve alterações significativas no comportamento do fluxo, comparado à válvula com apenas três portas laterais. Ao aumentar o diâmetro para 16mm, houve alteração significativa do perfil de velocidade, reduzindo a assimetria de fluxo, fato que pode contribuir para a redução no gradiente térmico ao longo do molde, diminuindo a possibilidade de ocorrência de defeitos no material lingotado. Com o aumento da dimensão da porta inferior observou-se também redução na velocidade de impacto do jato principal e consequentemente reduziu-se a velocidade do fluxo ascendente, o que evita refusão da pele e entranhamento de escória.Item Applying virtual reality model to green ironmaking industry and education : ‘a case study of charcoal mini-blast furnace plant’.(2017) Vieira, Cláudio Batista; Seshadri, Varadarajan; Oliveira, Ricardo Augusto Rabelo; Reinhardt, Pablo; Calazans, Patrícia Moreira Procópio; Vieira Filho, José BatistaA virtual reality (VR) model has been developed in the case of a generic green ironmaking industrial unit, namely a typical charcoal mini-blast furnace (CMBF) plant in Brazil. The VR prototype construction of the CMBF plant has been implemented through integration of data in different softwares and hardwares, including detailed engineering design of various auxiliary units and major equipments with realistic project parameters. Through the VR technology, one can actually have the unique experience visiting all parts of the CMBF plant, promote technical discussions on engineering and process control with users and improve information handling, communication, safety, maintenance procedures and development of advanced engineering projects in the field. VR industry-professional education platform can be used in universities, museums and industries with great benefits to students, workers and users.Item The influence of the geometry of a three orifice nozzle on the flowfield inside a beam blank mold.(2017) Gabriel, Weslei Viana; Peixoto, Johne Jesus Mol; Silva, Ciro Azevedo; Silva, Carlos Antônio da; Silva, Itavahn Alves da; Seshadri, VaradarajanA single nozzle design with three lateral ports has been proposed to feed a beam blank mold. Techniquesof physical modeling and computational fluid dynamics (CFD) were applied to evaluate the fluid flowas a function of port angle, immersion depth and flow rate. The overall features of the flow field are notaffected by changing the values of these parameters. The proposed design is characterized by: increasingfluctuation intensity at the meniscus and high impact velocities in certain regions of the broad face of theflanges. The oscillation intensity increases with decreasing immersion depth, increasing inclination of theexit ports, and increasing flow rates. These values vary also along the free surface of the mold, being largeron the flange opposite to the submerged entry nozzle (SEN) for all configurations. The impact velocitiesat the flange were affected only by the flow rate, reaching a maximum value of 0.45 m/s.Item A kinetic model applied to by injection of lime-based the molten powders.(1997) Seshadri, Varadarajan; Silva, Carlos Antônio da; Silva, Itavahn Alves da; Krüger, Paulo Gustavo vonAkinetic model of hot-metal desulfurization by deep injection of synthetic powdermixtures is presented. The approach takes into consideration the transient contribution due to the particles dispersed in the bulk metal and those located at the bubble-metal interface, the influence of the carry-over slag as well as the volumeand composition of the top slag. Themodel has been utilized to assess the influence of the treatment temperature, rate of injection of powdermixtures, gas flow rate and initial concentration of sulphur over the desulfurization kinetics. In the second part of this study an analysis of the industrial data for injection of powdermixtures using this model is described.Item Fluid flow and mixing characteristics in RH degasser of Companhia Siderúrgica de Tubarão, and influence of bottom gas injection and nozzle blockage through physical modelling study.(2004) Silva, Carlos Antônio da; Silva, Itavahn Alves da; Martins, Ernani Márcio de Castro; Seshadri, Varadarajan; Perim, Carlos Alberto; Vargas Filho, Geraldo AlvesA physical model based on similarity principles has been constructed for simulating the RH degasser of Companhia Sideru´rgica de Tubara˜o (CST), Vito´ ria, ES, Brazil. The influence of gas injection through nozzles in the upleg with simultaneous bottom injection of gas, as well as the influence of nozzle blockage, on the circulation rate has been investigated. In addition, mathematical relationships for mixing characteristics in the process have been evaluated.