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Recovery of Uranium from the Waste of UCF Plant By Means of Solvent Extraction Method

Moazen, Marziye | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42478 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Samadfam, Mohammad; Taghizadeh, Mohammad
  7. Abstract:
  8. During various stages of processing uranium in Isfahan’s UCF plant, liquid waste containing uranium compounds, is directed to evaporation lagoons. Gradually, a considerable amount of precipitation will form at the bottom of the lagoons. Since the concentration of uranium in evaporation ponds is relatively high, it seems that in addition to environmental issues, recycling uranium from existing pools is also economical. Uranium may be recovered from an aqueous solution by precipitation, solvent extraction and ion exchange. The solvent extraction is the best option for our purpose because of simple operation without increased consumption of heat or chemicals. It is also preferable when large amounts of metals are to be separated. Among industrial equipment, pulsed sieved columns are the best choice. Because of their high efficiency and less floor space, pulsed sieved columns are more applicable in nuclear industry. In this research, in order to recover uranium from sludge of evaporation lagoons, a pulsed sieved column was used and several experiments were carried out to investigate the effect of operational factors on mass transfer quality such as overall volumetric mass transfer coefficient, the extraction yield and height of each transfer unit. The parameters tested in each experiment were: dispersed phase flow rate, continuous phase flow rate and pulse intensity. In all experiments the organic phase was the solution of 5%D2EHPA diluted in kerosene and the aqueous phase was the solution of evaporation lagoons precipitates in water whose PH and concentration was adjusted before the experiments. The results showed that the increase in pulse intensity, leads to a considerable increase in uranium extraction efficiency and overall volumetric mass transfer coefficient. Also the height of each transfer unit decreases and in this manner the column performance improves. In case where the continuous phase flow rate increases, the overall volumetric mass transfer coefficient and the height of each transfer unit increase, so the extraction yield decreases and the column performance reduces. The increase in dispersed phase flow rate, leads to a slight increase in uranium extraction efficiency. The results also revealed that the plug current model usage and ignoring the axial mixing, could lead to 30% error in calculations
  9. Keywords:
  10. Oranium ; Solvent Extraction ; Pulsed Sieve-Plate Extractor ; Mass Transfer Coefficient ; Continuous Phase ; Dispersed Phase

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