Sharif Digital Repository

One of the steps in the production of nuclear fuel pellets used in the core of a nuclear reactor is sintering. Sintering means the consolidation of a pressed powder sample into an integrated solid. This process can be done in different ways, such as traditional sintering, microwave, spark plasma, etc. In the process of fabrication of nuclear fuel pellets, after producing uranium dioxide in powder form and making corrections on the size distribution of powder grains, it would be nolded and then sintered. In this research, the temperature evolution of the green pellets introduced to microwave heating were investigated. In this report, a brief overview of the principles of microwave heating is... 

In this study, the heat and mass balance of rotary kiln of iron pellets induration was simulated. Due to large amount of heat transfer calculations, a quasi three-dimensional model has been used in this study. First, the freeboard heat condition was simulated via fluent program and the average temperature of freeboard was stablished. Then, a one-dimensional heat transfer model was developed using heat transfer equations. In this model, the heat transfer via conduction, convection and radiation in different parts of the kiln was included. Also, the bed reactions and their effect on bed temperature were evaluated. Finally, transversal movement and velocity of particles was studied. Transversal... 

Uranium dioxide (UO2) has been widely used as nuclear fuel in water cooled reactors since 1960s. UO¬2 is a refractory oxide with a melting point in excess of 28000C and therefore, requires high sintering temperature around 17000C in a hydrogen atmosphere for several hours. In the conventional method, the sintering is incorporated with indirect heating of green pellets in a refractory-type electrical resistance furnace. This furnace, however, uses a large number of expensive heating elements and refractory materials to achieve and maintain the high temperature for a long time. Moreover, it consumes much electrical energy and time. Since nanocrystalline materials contain a large fraction of... 

In this study, the effect of iron ore concentrate morphology on green pellet quality was studied. In order to produce concentrate with different morphology using ball mill, ball charge (20-40 %V), grinding time (30-50 min) and ball distribution (15 mm, 23 mm, 15+23 mm) was varied. It was deduced that increasing grinding time and ball charge would result in reduction of D80 but would increase Blaine number. The interaction parameters of ball distribution-grinding time and ball distribution-ball charge had significant effect on Blaine and D80. It was also observed that mixed level of ball distribution would lead to higher Blaine numbers. The equation obtained by CCD was verified by the... 

As one of the most important agglomeration methods, pelletizing has a very important place in the iron and steel production chain. In the present study, the feasibility of improving FeO index in the final product of Pellet Factory No.1 of GolEGohar Mining and Industrial Company was investigated. The remaining FeO in the iron oxide pellet represents the amount of Magnetite that was not oxidized during the pelletizing process. The remaining FeO in the primary Magnetite is a disturbing structure for the direct reduction process and will cause a decrease in the compressive strength of the pellet (CCS) and as a result it will be crushed. Therefore, the percentage of the remaining FeO in the...