| Summary: | 碩士 === 國立臺北科技大學 === 資源工程研究所 === 107 === In this study, the effects of various parameters on producing sodium carbonate and lithium carbonate by injection of carbon dioxide into concentrated brine have been investigated. These parameters including the concentration of sodium chloride, lithium chloride and ammonia with the change of temperature. According to the difference between the formed carbonates, sodium ions and lithium ions are separated from the concentrated brine. It has been found that the amount of precipitation increases with increasing the concentration of sodium chloride. When sodium chloride concentration was 18 g/50 ml, the highest removal fraction of sodium ions achieved 50.47%. And when the concentration of lithium chloride was 13.05 g/50 ml, 15.58 g precipitation with 87.4 wt. % lithium carbonate formed. In addition, the concentration of ammonia in brine affects the formation ratio of carbonates. With 5.4 g ammonia in NaCl-brine, the fraction of sodium carbonate in the product reaches 95.8%. And the fraction of lithium carbonate in the product reaches 99.1% with 2.7 g ammonia in LiCl-brine. Moreover, increasing temperature reduces the production of sodium carbonate but enhances the lithium carbonate fraction in the product. The study also shows that when the mass ratio of NaCl/LiCl is higher than 10, it is ineffective to obtain lithium carbonate. Finally, this study try to use the bubble-liquid mass transfer model to simulate the process of carbon dioxide dissolution. It reveals that the mechanisms of carbon dioxide dissolution are complicated. In addition to the effect of hydroxide ion in brine, heat transfer, mass transfer and its kinetics interact with each other. Only the integration of all actions will establish the carbon dioxide dissolution model for predicting the production of carbonates using injection of carbon dioxide into concentrated brine.
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