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Thiobacillus ferrooxidans에 의한 우라늄 침출과 이중기포탑 반응기에서의 동특성

Uranium Leaching by Thiobacillus ferrooxidans and Dynamic Characteristics in Draught-Tube Reactor

이현섭 표관웅 유연우 김철

Lee HS Pyo KW Ryu YW Kim C

HWAHAK KONGHAK, February 1997, 35(1), 14-20(7), NONE

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Abstract

본 연구는 이중기포탑 반응기에서 저품위 우라늄광으로부터 우라늄의 세균 침출에 대한 실험과 침출반응 기작을 제안하고 반응기의 동특성을 규명하였다. Thiobacillus ferrooxidans에 의한 이중기포탑 반응기에서 우라늄의 침출률은 90% 이상을 얻었으며, 우라늄 침출의 기작은 세균증식에 따른 자동 촉매반응이며, 율속단계는 세균에 의한 Fe²⁺의 산화속도가 우라늄 침출속도를 지배하였다. 또한 Fe²⁺의 전화율 X_Fe를 구한 후 이를 이용하여 우라늄 침출 속도식을 도출한 결과 우라늄 침출의 실험값이 이론값과 잘 일치하였다. 이중기포탑 반응기는 플러그 흐름(plug flow) 으로 재순환되는 N-tanks-in-series model로 나타낼 수 있었고, 폭기관에서의 체류시간 t_i와 순환관에서의 체류시간은 각각 1.88 sec와 2.50 sec였으며, variance는 0.05이었다.

Biological leaching of uranium from low-grade uranium ore was conducted in a draught-tube reactor to establish the rates of oxidation of ferrous iron and leaching of uranium, and the identification of dynamic characteristics. Overall uranium leaching process includes a sequence of two steps, the biological and the chemical processes, in which the biological step is the rate limiting. In the leaching by using a microorganism, Thiobacillus ferrooxidans, over 90% of uranium was leached from low-grade uranium ore within 14 days. An autocatalytic kinetic mechanism was proposed for the overall leaching process. Based on the proposed kinetic mechanism, the change in fractional conversion of ferrous iron and the overall rate expression in terms of fractional conversion of uranium were derived. The conversion of uranium predicted by these equations was in good agreement with the experimental data. The N-tanks-in-series model with plug flow recycle was employed to depict the dynamic characteristics of the draught-tube reactor. The residence times in the N-tanks-in-series and plug flow regions were found to be 1.88 sec and 2.50 sec, respectively with a variance of 0.05.

Keywords

Biological Leaching Thiobacillus ferrooxidans Draught-Tube Reactor

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