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Derivation of a Scalable Mass Ttransfer Equation for Adsorption of Uranium on Resin in Stirred Reactors

Naderi, Ali | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43612 (46)
  4. University: Sharif University Of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Outokesh, Mohammad; khanchi, Alireza
  7. Abstract:
  8. Resin In Pulp(RIP) is One of the most important processes for separation of uranium from ore while concentration of uranium in ore is low , based on adsorption of uranium that exist in the slurry on onion exchanger resins .uranium ore is dissolved in sulfuric acid and slurry that contain uranium is produced,then this slurry enter stirred reactors and adsorption process is performed.RIP are accepted universally and now adays countries such as canada,south africa and australia use this process when concentration of uranium in slurry after leaching process is 100-500 ppm.in iran also this process is performing in ardacan-saghand mine.Kinetic of adsorption process in stirred reactors has been modeled with variety of errors such as pesudo second kinetic equations, solution of fick equation with different boundary condition, complicatio of fick equation with langmuir equation and ferundlich equation in the particles,method of helfferich that is based on nernst-plank equation and using mass transfer coefficients which they depend on condition of process. unfortunately all of these methods only are used in lab scale while experimental results are well predicted by this equations but it is not clear that which one of these theorise can predict rate of adsorption of uranium on resins in pilot scale or full-scale better than others? with another expression which on of these equations are abale to scale-up for modelling of adsorption process in stirred reactors? In this thesis adsorption process was done by 3 different scale stirred reactors with clear solution that had been produced by leaching of uranium ore of saghand mine.stirred reactors was same numeraaly and had electromotors that can adjusted for creating dynamic similarity.at first this was found that if reynolds number in 3 reactors be equivalent rate of mass transfer of uranium from solution to the resins particle will not the same. On the other hand it was obvious from rate curves that when p/v (power input by stirrer per volume of reactor) in 3 different reactors are a number rate of adsorption remain constant.finally using two resistance model (homogenuos phase diffusion model) that its equations was solved by a numerical method ( cranc-nicholson ) rate of mass transfer was predicted and had good agreement with experimental results.mass transfer coefficient for different condition of process and diffusion coefficient of uranium in the resin also was predicted by this computer program.using obtained mass transfer coefficient an equation for adsorption of uranium in stirred reactors was derived that this equation are able to predict mass transfer coefficient for reactors with different scales.
  9. Keywords:
  10. Uranium Adsorption ; Ion Exchange ; Scalability ; Mass Transfer Modeling ; Stirred Tank Reactor

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