This paper presents the results of a study on carbothermal reduction of iron ore made under the microwave field in equipment specially developed for this purpose. The equipment allows the control of radiated and reflected microwave power, and therefore measures the microwave energy actually applied to the load in the reduction process. It also allows performing energy balances and determining the reaction rate with high levels of confidence by simultaneously measuring temperature and mass of the material upon reduction with high reproducibility. We used a microwave generator of 2.45 GHz with variable power up to 3000 W. Self‐reducing pellets under argon atmosphere, containing iron ore and petroleum coke, with 3.5 g of mass and 15 mm of diameter were declined. We obtained the kinetic curves of reduction of iron ore and of energy consumption to the process in the maximum electric field, in the maximum magnetic field and at different values of power/mass. The data allow analyzing how the microwave energy was actually consumed in the reduction of ore.
Fiberglass/thermoset matrix composite present important properties, such as specific mass and mechanical strength, aiming to replace some engineering materials. However, its mixture of different materials transforms them into an environmental problem, due to the complex recycling process. The highlight is meeting the demands of environmental pressures and for establishing recycling mechanisms, the proposal is to study physical recycling processes, focusing on the microwave-assisted pyrolysis process and also recovering fiberglass. The results were: humidity around 3 wt. %; the average loss of mass around 68 wt. %; the tensile strength is reduced by about 76 % when a composite with recycled fiberglass is laminated, as compared to the use of virgin fiberglass. This work establishing the physical recycling mechanism and route for composite materials, identifying the thermal degradation processes, for thus applying them to other materials, still considered environmental issues, technically and economically making these materials manufacturing processes viable, as well as establishing a recycling route.
An explor ator y test of dr ying zinc sulfate heptahydr ate was per for med to compare the efficiency of a microwave dr yer and an infrared dr yer. M oisture content was deter mined by titrating with EDTA the level of zinc in the sample. Results show that microwave dr ying is more efficient than infrar ed dr ying. A 95 % r eduction in dr ying time and a 7 % higher r emoval of water was obtained with microwave dr ying.Index Terms Drying, microwave industrial applications, zinc sulfate.
ResumoO presente trabalho apresenta um forno para a produção de ferro gusa por redução carbotérmica estimulada por micro-ondas de minério de ferro, na forma de pelotas autoredutoras. O forno de redução com potência regulável de até 15 kW de micro-ondas de 2.45 GHz foi especialmente projetado e construído para este processo. A estrutura do forno é em aço inoxidável e utiliza três geradores de micro-ondas focados para o centro de um aplicador cilíndrico. Com esta configuração conseguiu-se produzir um campo eletromagnético de alta densidade energética. As cargas de pelotas auto-redutoras, com massas em torno de 90 g e 30 g foram reduzidas em um cadinho de carbeto de silício. A potência de micro-ondas irradiada foi de 6 kW. A montagem do forno dispõe de uma balança elétrica adaptada para suportar o cadinho de redução. O presente forno dispõe de controle e medida da potência fornecida e refletida, permitindo medir a energia de micro-ondas efetivamente aplicada à carga. Esta característica permite realizar balanços de massa e de energia além de determinar a evolução da taxa de reação através da medida contínua da massa das pelotas sob redução, ao longo do tempo de processamento. Obtiveram-se curvas cinéticas de redução carbotérmica de minério de ferro incentivada por micro-ondas e de seu consumo de energia durante o processo. Palavras-chave: Forno redução carbotérmica; Micro-ondas; Ferro gusa. EQUIPMENT FOR CARBOTHERMAL REDUCTION OF IRON ORE APPLYING MICROWAVE AbstractThis paper presents of furnace for production of pig iron by carbothermic reduction of iron ore in the form of self-reducing pellets enhanced by microwaves. The reduction furnace with adjustable up to 15 kW microwave power of 2.45 GHz has been specially designed and built for this purpose. The furnace structure is made of stainless steel and has three microwave generators focused to the center of a cylindrical applicator. With this setup we were able to produce a high energy density electromagnetic field. The burden of self-reducing pellets with mass around 90 g and 30 g were reduced in a crucible silicon carbide. The power microwave radiated is 6 kW. The oven features an electric balance appropriately adapted to support the crucible reduction. This oven allows the measurement and control of power supplied and reflected establishing the effective energy applied to load. This feature allowed for mass and energy balances and to observe the evolution of reduction rate by continuously measuring of reacting mass during its processing. Curves for carbothermic reduction of iron ore were determined and, also, the energy consumption during the process. This feature allows to perform mass and energy balances and to determine the progress of the reaction rate by continuously measuring the mass of pellets under reducing along the processing time. Curves for carbothermal reduction of iron ore were determined and, also, the energy consumption during the process.
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